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In this guide:

Free online Photoshop tutorials and info:

Everything Photoshop:

Recommended Photoshop books:

Free online photography tutorials:

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Photoshop - A Beginner's Guide

Skip the introduction >>

Picture of camera This guide started out as a set of structured notes and links to help me to learn Photoshop (and that's what it still is).

When I realised that it would be useful for other people, I decided that it was worth the effort to turn it into the much more comprehensive guide that you see now.

My aim is to help you through the "Boot Camp" stage of learning Photoshop, and a bit further. If you are new to Photoshop, or if (like me) you use some of Photoshop's features but would like to explore more of its power, then this guide is for you.

What is the "Boot Camp" stage? Well, for me it was the effort needed to learn about Selections and Masks, Channels, Levels, Curves, Layers, Colour Spaces, Paint Tools and Blend Modes, and how all these things related to each other. It seemed that I needed to know a lot about each of them (except maybe blend modes) before I could "get" what Photoshop was about.

My experience is with Photoshop 7. Most of the information in this guide will also be useful with other versions of Photoshop, and may help with features of other programs such as Paint Shop Pro or the excellent freeware GIMP.

Note

Picture of compassThe right-hand panel of this page contains a summary of the links that I have found to be most useful. Most of these links will also appear in the main text of this page. External links will open in a new tab or window, because you might want to follow them for some distance - just close the new tab or window to return to this page.

A quick walk through Photoshop

Here are some typical steps I might carry out in improving a photographic image, just to give a flavour of Photoshop in action.

If you click the images you will be taken to more information about that subject, either within this guide or externally. External links open in a separate window - just close it when you're done to return to this guide.

Harbour mask The first thing I do is to crop (and if necessary rotate) the image, using the versatile Crop tool. Very few pictures can't be improved by cropping. Photoshop 6 onwards can also fix perspective errors when cropping.

The reason for cropping as the first step is to avoid unwanted parts of the image affecting the image-improvement steps that will come later.

Levels curve The next thing I often do is to use the Levels tool to improve the brightness, contrast and tonal range of the picture. Simply moving the sliders on the image histogram can make a huge and easy improvement to the picture. The use of this tool is worth studying in depth.  
 

Adjustment Layer I have learnt that it is best not to adjust levels on the original image. Instead, I create an Adjustment Layer for using the Levels tool. The concept of Layers and Masks is fundamental to Photoshop, and I strongly recommend that you watch Andy Heatwole's short video lessons on these (you will find more about these lessons below).

There are many advantages to using Layers in Photoshop. For now I'll just say that each Layer can be turned on and off to see its effect, each Layer can be revisited and changed independently from other Layers, and each Layer can have a Mask that affects which parts of the Layer(s) beneath it are going to be visible in the final image. Adjustment Layers (like Fill Layers) always have Masks.

By default, a new Layer (which can be an image or an Adjustment Layer) hides the Layer(s) beneath it. The Layer that I just created has an improved version of the original image, but the original version is still there in the (now hidden) background Layer.

Curves graph The next thing I do might be to improve contrast and detail in part of the image. The details in a bird's dark feathers, for example, might not be clear, although the rest of the picture might be OK. This is a job for the Curves tool, which is another one that is worth studing in depth.

I create another Adjustment Layer for the curves tool. First I run the mouse over the dark feathers, holding down the left mouse button, and watch a moving dot on the graph (which is initially a straight line) that tells me which part of the graph corresponds to the colours in the feathers. Then I alter the slope of that part of the graph, bending the line, and see the improvement to the contrast and detail in the feathers.

Picture of Layers with Mask The feathers now look great, but maybe I have messed up the rest of the picture. Here's where the Layer's Mask comes in. An opaque Mask is just a white image. A transparent Mask is a black image. Shades of grey on the Mask make it more or less transparent (darker grey is more transparent).

Now I have a reason for using a paint brush. I select a paint brush (a soft brush, in order to avoid hard mask boundaries) and paint black onto the white (opaque) Mask wherever I want the lower level to show through, which means everywhere except for the dark feathers. Painting black on a Mask effectively removes that part of the layer's image from the finished complete picture.

Actually, in this case I could more easily make the whole Mask black (transparent) by inverting it (Ctrl+I) and then use a white paintbrush just on the area of the Mask where the dark feathers are.

Picture of lasso If I needed to, I might also use one of the Selection tools to create a Selection (perhaps with a feathered edge, no pun intended) to limit the area where my brush strokes on the Mask would have an effect.

There's lots more I could do - for example, I could keep part of the picture sharply focused while progressively blurring parts that are further away from the lens, or I could adjust the brightness of the sky relative to the rest of the picture. You will find some examples here in this guide.

hue / saturation dialog box One of the last things I often do is to increase the saturation of all the colours by a small amount, using the tool described here.

After doing everything else (except for sharpening) I flatten all the layers into one layer (I save the file with layers first, if the picture is worth further work) and then save the image as a jpeg file, possibly resizing it.
 

Picture of sharpening letters Whatever else I do, the final step is sharpening the otherwise-finished picture, which I do using the curiously named unsharp Mask (so-called because of the temporary blur used to create the edge-locating region within which sharpening happens).

Using the tool is easy when you understand it, but understanding it takes a bit of study. It's worth it, though, as sharpening is essential on all digital images if you want best quality.

If you are interested in seeing the finished image from the above work flow, you will find it in my Whitby Photoblog (Page 2).

Picture of robot Achieving particular effects using Photoshop can take many individual steps. Luckily, these can be automated in various ways, as described here in this guide.

Which version of Photoshop? Can I afford it?

Picture of green dollars The first problem in getting to grips with Photoshop is deciding which version to use, and finding the money to pay for it!

I was lucky to be given a copy of Photoshop 7 by a mega-kind photographer friend (who was moving up to a newer version). This has more power than I am ever likely to use, but I find that I am using more and more of its features as I go along. Much of the power of Photoshop comes from the zillion combinations of ways of using its features.

Most of the notes in this guide come from my experiences so far with Photoshop 7. The notes will probably apply to later versions of Photoshop (Photoshop CS), and may also apply to earlier versions of Photoshop and to the cut-down version of Photoshop (Photoshop Elements, see below).

You might consider buying a (relatively) cheap copy of Photoshop 7. You can find them on eBay, for example, often being sold by people who have moved on to later versions. You need to be careful of licence issues, but if you pay by PayPal on eBay then you have a signficant degree of consumer protection.

Books for the superseded Photoshop 7 (often with attached CDs, some with a trial version of Photoshop) can also be purchased for as little as $10 or so. More of that below.

  • Photoshop CS
  • What you won't find in this guide is any discussion of the new features of Photoshop CS - but there are many links about these new features here.
  • GIMP: an excellent freeware alternative to Photoshop
  • Check out the GNU Image Manipulation Program (GIMP), available for several platforms including Windows, Mac OS X and Unix.
  • It is very rich in features, including correction of perspective and lens barrel distortion, full alpha channel support, layers, scripting, and many others.
  • You will find many other links about GIMP here, and comparisons of GIMP and Photoshop here.
  • Many more free alternatives to Photoshop
  • You will find a great list of 30 free photo and image editors here.

What is the difference between Photoshop Elements (PSE) and Photoshop?

A useful answer to this question can be found here.

The interesting thing is that many of the "missing" features in PSE are actually undocumented functions that can be unlocked - see the link for details.

Photoshop Boot Camp, and how to survive it

Picture of boot camp training Getting to grips with Photoshop for the first time is tough - don't I know it!

Here is some advice for getting through it without too much pain:

  1. You really, really need to go through some operations to set up Photoshop properly, and to learn some of its basic operations, before you can start having fun with it. Gregory Georges calls this "Boot Camp", and he isn't kidding. His book (see below) is an excellent way to get you through it. Hopefully the page that you are reading now will also help.
  2. However good the on-line information is, buy at least one real paper book on Photoshop, preferably with an accompanying CD that will have many of the author's before-and-after photos on which you can practice. See below for some suggestions.
  3. If you have a single monitor, and it isn't wide-screen, seriously consider adding a second monitor (which is easy if your graphics card has a dual head). You will need the extra work space, since Photoshop makes use of a large number of palettes which are really control and information panels. Without extra workspace you have to keep hiding and unhiding them (see Vital Shortcuts below) in order to work on your image(s). The second monitor can be a cheap 15" one. Alternatively, move up to a large wide-screen monitor. The two-monitor solution is better, IMO, and you will find lots of other uses for a desktop stretching across two monitors apart from Photoshop itself.
  4. Do learn the Vital Shortcuts. They will make your life much easier.

Recommended Photoshop books

Picture of book coverGold Award symbol I can really recommend this 340-page book by Gregory Georges (which is also available for later versions of Photoshop) - click the image for examples of where to buy it. Elsewhere in this guide, I refer to it as 50FPT.

Because Photoshop 7 isn't the latest version, it's surprisingly cheap.

It takes you through the "Boot Camp" process of setting up Photoshop and the basic techniques that you must learn.

Then it explores many different ways of having creative fun with Photoshop, teaching you relevant techniques as you go along.

The accompanying CD-ROM (essential IMO) contains many image examples to support the exercises, and a 30-day trial version of Photoshop 7.

You can download a PDF version of this book, but it is nothing like as useful as the real thing. Sometimes there is no substitute for a real paper book (and in this case, the CD as well).

Picture of book Gold Award symbol As a next stage up from the previous book, I can also strongly recommend Photoshop 7 Artistry by Barry Haynes and Wendy Crumper (which I refer to elsewhere in this guide as P7A).

This book has 466 information-packed pages, plus extra chapters on the accompanying CD-ROM.

As with the previous book, it has later versions and this version can now be bought very cheaply.

It's more advanced than the previous book, and it's the place I go to when I want full, accurate details about some aspect of Photoshop.

If you want to know which books other people recommend, go here.

Free instructional videos

Movie camera iconGold Award symbol Andy Heatwole (a.k.a. LargeFeather) has produced several really excellent instructional videos on Layer Masks & Adjustment Layers.

These topics are fundamental to the effective use of Photoshop. The videos (lasting about 5 or 6 minutes each) should be essential viewing for anyone learning Photoshop.

A small warning: the first video has a longish voice introduction while the screen is mostly grey. This isn't a fault - keep watching!

Go here, or click the movie camera icon above, for a full summary of the content of each video, together with a link to play it.

Don't miss out on other great stuff on Andy's site.

On the same page you can download the lessons' PSD files as a RAR file.

  • You may not have met a RAR file before. It's another kind of zip file, and some versions of WinZip won't work with it. To unzip it when you have downloaded it get a free evaluation copy of the WinRAR program from:
  • www.rarlab.com/download.htm

  • When I went there a long time ago, I chose WinRAR version 3.62 from the large number of choices at that site. Any appropriate later version will do.

Shortcuts

Wile E. Coyote running Before rushing on to the vital shortcuts themselves, you need to know this...

Modifier keys (their logic, and translating between PC- and Mac-speak)

Although Photoshop runs fine on a PC, it was developed for the Mac. One of the main differences you will encounter is how the modifier keys are referred to.

Here is a translation. It may also help you to understand the logic behind the use of these keys, even if the logic isn't always consistently applied!

MODIFIER KEYS
PC Key Mac Key Typical Effects (With a Few Examples)
Shift Shift Magnifies, constrains or makes permanent the effect. Increases the distance when you move something using arrow keys. Makes a line-drawing drag vertical, horizontal or at 45 degrees. Constrains a resizing drag to the same proportions. Turns the eye dropper into a Colour Sampler, e.g. when placing a Colour Sampler point marker (which is permanent until you delete it).

In Windows, makes the delete key delete a file permanently, as distinct from moving it to the recycle bin.
Alt Option Changes the effect to an alternative or opposite effect. May bring up alternative buttons in a palette (e.g. substitutes Reset button for Cancel button in Levels Palette).
Control Command Turns a normal (non-function) key into a command.

Can also turn a mouse-click that would normally just select something into a command to do something to what is being clicked (e.g. Control/Command-clicking a Mask thumbnail loads that Mask as a Selection).

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The vital shortcuts

Here are the shortcuts that you really must know (at least I would be driven crazy if I didn't know them):

THE VITAL SHORTCUTS
Tab Hides / shows all the palettes (control and information panels). Really useful if you don't use two monitors or a large wide-screen monitor. Otherwise you have to use the Windows menu or the Function Keys (F5 to F9 in my setup).
Shift+Tab Hides / shows all the palettes except for the Tool Palette and the Tool Options Bar. In other words, it keeps the Tool Palette and its options permanently visible.

Note that Alt+Tab is already taken by Windows (it cycles through your applications), as is Ctrl+Tab (which cycles through your windows within an application, including Photoshop if you have more than one image open)
Spacebar Temporarily brings up the dragging (hand) tool, so that whatever other tool you are using, you can move your view of the image and then continue. As a mnemonic, I think of "space" as something I want to move around in.
Ctrl+Spacebar Temporarily brings up the zoom tool (zoom in)

If you have a mouse wheel, use Alt+Mousewheel instead to zoom in and out (add Shift to accelerate)
Alt+Ctrl+Spacebar Temporarily brings up the zoom tool (zoom out)

If you have a mouse wheel, use Alt+Mousewheel instead to zoom in and out (add Shift to accelerate)
Ctrl+0 Makes image fit screen. As a mnemonic, I try to think of 0 (zero) as representing the useful screen area. Ctrl+O (O the letter) is of course already taken for Open Document.
Alt+Ctrl+0 Zooms image to actual pixel size. After doing this, you might really want to navigate around the picture by dragging the red box on the Navigator Palette.
F Cycles through 3 different ways of looking at your image. After using Ctrl+0 to make the image window fit on the screen, the first press of F will remove the window frame and show the image surrounded by grey space. Great for (say) using the crop tool to surround the whole image, before adjusting. The next press of F gets you more or less a full screen, with black background. I remember this shortcut as "Flip View".
Arrow
↓ ↑ ← →
Nudge something by one pixel or one digit. For example, if you have used the Move tool to position one image on top of another, you can adjust the position very finely using one of the arrow keys.

The up and down arrow keys will also adjust numbers up or down if the cursor is in a box containing a number.
Shift+Arrow Same as an arrow key, but magnifies the effect by a factor of 10
B, D, X This is a really common and useful sequence of painting shortcuts. B selects the Brush tool. D resets the default foreground and background colours for whatever you are doing (e.g. black and white if you are working with Masks). X exchanges the foreground and background colours.
[ Decreases the size of the paint brush, while being able to see the image and the paint brush together (make sure Caps Lock is off - see here)
] Increases the size of the paint brush, while being able to see the image and the paint brush together(make sure Caps Lock is off - see here)
1,2,3... 9,0 When a paint tool is selected and the cursor isn't inside a number box, you can set the opacity quickly using a number key (1=10%, 2=20% ... 0=100%)
Shift+Backspace Fill dialog
Alt+Backspace Fill with foreground colour
Ctrl+Backspace Fill with background colour
Ctrl+I Invert image

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All of the keyboard shortcuts

Gold Award symbolIf you would like to see all of the keyboard shortcuts, that's easy:
just go here.

Trevor Morris Photographics have kindly provided keyboard shortcuts for all versions of Photoshop - just select the one you are interested in.

What is more, the excellent "cheat sheets" are divided into two sections. The first section presents the shortcuts that apply to each menu, the second section organizes them alphabetically by key.

If your eye-sight is like mine, don't print them out unless you can print on A3 paper!

Selections and Masks

Introduction to Selections and Masks

Lasso and Mask Selections (shown as "marching ants") and Masks (grey-scale images stored in Channels) are the bread-and-butter of working with Photoshop.

A Selection isolates a part of the Layer or Channel that you are currently working with. Whatever you do is focused on the selected area.

A Selection sticks around for as long as you need it. Until it is turned off using Select > Deselect (Ctrl+D), you can change the active Layer or Channel and the Selection is still in force.

Lasso, arrow, mask A Selection can be saved in, and loaded from, a Mask Channel (how?).

What is more, the Mask Channel in question can be in any other document that Photoshop currently has open, providing that it has the same pixel dimensions as this one (see this tip).

A Mask Channel (which can be viewed and edited from the Channels Palette) can be seen as "a Selection saved for later".

A Mask Channel can also be created and edited without starting with a Selection, as described here.

Mask Channels don't do anything until one of them is loaded as a Selection, or is used as a Layer Mask (see below).

Quick Mask buttonsq A Quick Mask is a temporary Mask Channel (called Quick Mask) that you create using the Quick Mask Mode tool. It's intended as a fast way of creating a Selection by painting on a mask, instead of using the Selection tools. More about that here.

Picture of Layers with Mask A Layer Mask is a Mask Channel that is always associated with (and named in accordance with the name of) a particular Layer. It is only visible in the Channel Palette when you are working with that Layer.

Most often, you work with a Layer Mask by clicking its thumbnail in the Layers Palette. If you paint, for example, you are now painting on the Mask.

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Selections

Gold Award symbol Picture of lasso For some good introductions to the Selection tools, click the lasso icon or go here.

(If you read at least one of them now, it may help with what follows.)

Working with photographs, I usually make selections with the Free-form Selection tools (the various Lasso tools and the Magic Wand tool), and only rarely with the rectangular/elliptical Marquee Selection tools.

Wile E. Coyote running The important shortcuts for use with these tools are well worth learning. You will find most of them half-way down this page (which is a page for the Marquee tools, but with a few obvious exceptions they are generally applicable to all selection tools).

It's especially worth remembering that:

  • the shift key adds to an existing selection (cursor shows +)
  • the alt key subtracts from an existing selection (cursor shows -)
  • the two keys together reduce the selection to the intersection (overlap) of the existing and the new selections (cursor shows x)
  • the alt key temporarily switches from the Polygonal Lasso tool (move and click) to the normal Lasso tool (draw with mouse key down), and vice versa.
  • the delete key has a "go back one step" effect, e.g. go back to previous drop point (Magnetic Lasso) or previous drawn pixel (Lasso), which is particularly useful with the Magnetic Lasso tool.

Selections with the Marquee and Lasso tools can (and sometimes should) have feathered edges, which provides a smooth transition between the selected and unselected areas.

  • Note that feathered edges in a Selection correspond to shadings of grey in a Mask, and vice versa.

You can also use the Pen tool to create smooth curves, called Paths, that have a number of advantages over normal selections, including being editable once created. A good example of their use will be found here.

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Improving an initial selection

Using the Free-form Selection tools, often the Magic Wand, my first selection is usually not quite right. Using the Magic Wand with the Shift key, I can add to the selected area - the Magic Wand's Option Bar will let me set various options.

But here's the thing: I am only interested in getting the outside boundaries of the selection right, or nearly right. I don't care about any unselected bits in the middle of the selection.

Why is that? Well, it's because I am shortly going to view the selection as a Mask. Using white paint on the Mask, I can simply paint out all the little unselected areas that I want selected.

  • A useful tip for cleaning up a Selection or Mask...
  • Picture of Light BulbSometimes you start with a Selection, convert it to a Mask, and find that correcting the Mask needs you to paint a straight line on the Mask (black to remove an area, white to add one).
  • In this case, remember that if you click once where the line needs to start with a Paint brush tool, move the brush to a new position and then click again with the Shift key down, you will draw a straight line between the two points.
  • (This is like stretching a piece of masking tape between your fingers and setting it down carefully.)
  • If you want to convert the Mask back to a Selection, you do that as described here.

Another way to start a rough selection (to be improved later) is to use the Lasso tools to select an approximate shape that is just inside the boundary that you really want. Then you can use Select > Grow or the Magic Wand tool to expand the selection.

Picture of Light Bulb There's a wee problem with Select > Grow (which grows a selection using expansion criteria but only in contiguous areas) and with Select > Similar (which does the same thing but non-contiguously, i.e. to anywhere in the image that matches the expansion criteria).

The problem is: where are the expansion criteria? With Photoshop 7, anyway, you find them by selecting the Magic Wand tool - they're on that tool's Option Bar. This is why I prefer to use the Magic Wand tool to expand an initial rough selection.

Masks

Picture of mask Gold Award symbol For a good compact introduction to the various kinds of Masks, click the Mask icon or go here.

(If you read it now, it may help with what follows.)

At present, all of my references to Masks will be to pixel Masks.

A Mask is a grey-scale image that lives "alongside" the image being worked on (it lives in a temporary or permanent Channel associated with the active image).

  • Note:
  • Depending on what you are doing, the Mask may be presented to you in a shade of colour, by default a semi-transparent ruby red. The actual Mask, however, is always grey-scale.

A masked-out area on the active image is shown as black on the Mask. An unmasked area on the active image is shown as white on the Mask. A partially-masked area of the active image is shown as a shade of grey on the Mask (the darker the grey, the more opaque is the mask). Anything you do to the active image will only have an effect in the unmasked or partially-masked areas.

Picture of Layers with Mask A Layer Mask has an additional property of transparency, relating to Layers beneath the Layer that it is associated with:

  • For all types of Layer, the darkness of the Layer Mask determines how transparent a part of the Layer is.
  • Areas of transparency on the Layer are shown as black on the Mask. These areas will allow lower Layers to be visible.
  • Shades of grey on the Mask make it more or less transparent (darker grey is more transparent).
  • Opaque areas of the Layer are shown as white on the Mask. These areas will hide anything in lower Layers.
  • The Layer Mask also masks any effect applied to this layer, as described above, whether it is an Adjustment Layer (as here) or a Layer containing an image, fill colour or pattern.

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Creating and editing a Layer Mask (and other Mask Channels)

You create a Layer Mask in one of the following ways:

  1. You create an Adjustment Layer or Fill Layer. This automatically creates a Layer Mask to go with it. As an extra bonus, any Selection that you have in force is automatically reflected in the new Layer Mask.
  2. Arrow pointing to new mask You select a Normal Layer (not the Background) that doesn't have a Mask, or create such a Layer, and add a Mask to it using one of the buttons on the Layers Palette (or by Layer > Add Layer, which is better because you get options for the initial setting of the Mask).
  3. Picture of Venetian mask and Photoshop mask You can convert an image to a Mask, in several steps. One way of doing this involves the Levels tool followed by cleanup with a Brush tool. This is the same technique as the one described in my section on How to create a sky mask.

Layer thumbnails You edit a Layer Mask by first selecting its thumbnail in the Layers Palette, as shown in this image (mouse-over to see what happens when the image, rather than the Mask, is selected).

You will then often use one of the Paint tools, creating white, black or shades of grey. In fact you can use any tool that will change the pixels in a grey-scale image, including a blur filter (e.g. in order to soften boundaries), a curves adjustment, or anything else you can imagine. (If you paint on a mask with a red colour, it will come out grey... just in case you were wondering.)

  • You won't see the Mask itself while you are doing this. You will just see any effects caused by the Mask becoming more or less transparent.
  • If you want to see the Mask you are editing at the same time as the image you are looking at (which may be a composite of several layers), you can toggle the Mask's visibility on and off using the \ key. You will see the Mask as a transparent ruby overlay. To change the overlay's colour, double-click the Layer Mask's thumbnail.
  • If you want to see just the Mask that you are editing, e.g. when tidying-up missing patches, alt-click the Layer Mask's thumbnail, and repeat to hide the Mask again.

You can edit a Mask Channel directly in a similar way, first selecting its thumbnail in the Channels Palette.

  • What you will see as you are editing depends on what other eye symbols are selected in that Palette. If the other eye symbols are all unselected, you will see just the Mask itself.
  • You can toggle a mask overlay on and off just as you did for a Layer Mask, using the \ key, and also change the overlay colour in the same way as before. It's easy to get confused: the overlay that you are toggling here is a view of the current Layer Mask, if any.

You can create a new Mask Channel by duplicating any existing Channel, including any Colour Channel. Remember:

  • all Channels, including Colour Channels, are grey-scale images;
  • a new Mask Channel won't do anything until it is loaded as a Selection.

How do you duplicate a Channel? Here is something really worth remembering:

  • Context-Sensitive Menus
  • Picture of Light Bulb Any time that you want to do something to an object (e.g. you want to duplicate a Channel), just pull up its context-sensitive menu, which lists everything you can do to that object at this moment in time. Then you select what you want to do from the pop-up list.

    • Menu You pull up a context-sensitive menu by right-clicking the object (on a PC) or by control-clicking the object (on a Mac).
    • In the case of a Channel, the object is represented by its thumbnail in the Channels Palette.
    • Other things you can right-click for a context menu include the thumbnail of a Layer in the Layers Palette, or the Title Bar of a document, or if you are using the Move tool (V), you can right-click the document window to get a list of Layers so that you can choose the right one.

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Saving, restoring and loading Selections

A Selection can be saved in, and loaded from, a Mask Channel.

As usual, Photoshop provides a zillion ways of doing the same thing. My preference is to use the Select menu.

Lasso, arrow, mask To save a Selection in a Mask Channel, choose Select > Save Selection. You can choose a new or existing Channel as a destination:

  • If it's a new Mask Channel, I suggest that you give it a meaningful name.
  • If it's an existing Mask Channel, then you can decide how to combine your selection with what is already there.

The destination Channel doesn't have to be in the current document. You can place it in any document that Photoshop currently has open, providing that it has the same pixel dimensions as the current one (see this tip).

Lasso, arrow, mask To load a Selection from a Mask Channel, choose Select > Load Selection, and pick the Mask Channel you want to load from (which can be located in any open document that has the same pixel dimensions as this one):

  • If you don't have another Selection already, then the Mask will become your new Selection.
  • If you do have another Selection already, then you can decide how to combine the Mask with the Selection that is already there.

If you simply want to load a Mask as a Selection, discarding any Selection currently in force, then you can also Ctrl-click (PC) or Command-Click (Mac) on the Mask's thumbnail.

  • Notes on loading a Mask as a Selection using Ctrl/Command-click
    1. The thumbnail that you click on in this case can either be in the Channels Palette or the Layers Palette.
    2. The thumbnail does not actually have to be of a Mask - it can be of any grey-scale image, including one of the RGB Colour Channels or even the composite RGB Channel. However this probably won't be useful as a Selection unless the grey-scale image consists mostly of a combination of pure white and pure black, with a few shades of grey thrown in. If there is much area containing shades of grey then the resulting Selection will be highly feathered.
    3. If the thumbnail you click on is of a colour image (but not in the Background Layer), then you end up with a Selection of the whole image - which is not useful at all.
    4. These notes apply only to the Ctrl/Command-click method. They do not apply to the Select > Load Selection method.

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Using the Quick Mask mode

  • Short Version
  • A Quick Mask is a temporary Mask Channel (called Quick Mask) that you create using the Quick Mask Mode tool. It's intended as a fast way of creating a Selection by painting on a mask, instead of using the Selection tools.

You should already be familiar with the normal way of editing a Mask, described above (if not, please read that first!). Quick Mask mode is a way of doing almost the same thing with some button shortcuts.

Picture of Quick Mask buttons Near the bottom of the Tools palette, you have a couple of buttons that normally look like this, when you are not using Quick Mask mode.

Picture of Quick Mask buttons In order to use "default" Quick Mask mode, click the right-hand button. When your mouse is hovering over it, the button should look like this. What it means is that when you see a colour overlay, it will correspond to the area that will not be Selected.

Picture of Quick Mask buttons In order to use "inverse" Quick Mask mode, alt-click the right-hand button. When your mouse is hovering over it, the button should look like this. What it means is that when you see a colour overlay, it will correspond to the area that will be Selected.

  • In order to return to the default mode, alt-click the button again.

The Quick Mask buttons use a colour overlay (by default, transparent ruby red) to indicate the mask area.

  • You can change the overlay colour by double-clicking the button. You can then change the transparency of the colour.
  • If you want a different colour as well, double-click the block of colour that appears and pick another one.

Picture of Quick Mask buttons In default Quick Mask mode the colour overlay shows where the Mask itself is white. This is the area that will be not be Selected when you exit Quick Mask mode. You can add to this "to be unselected" area with white paint, or subtract from it with black paint.

  • What may confuse you is that when you use normal Masks, and convert to and from Selections, the non-Selected area corresponds to black areas on the Mask.

Picture of Quick Mask buttons In inverse Quick Mask mode the colour overlay shows where the Mask itself is black. This is the area that will be Selected when you exit Quick Mask mode. You can add to this "to be selected" area with black paint, or subtract from it with white paint.

  • What may confuse you is that when you use normal Masks, and convert to and from Selections, the Selected area corresponds to white areas on the Mask.

If you take a peek at the Channels Palette and see how Quick Mask is represented then you'll know whether to use black or white paint to do what you want.

If you use the Quick Mask mode strictly for what it was intended, and don't mix it with other ways of working with Selections and Masks, hopefully you won't get too confused.

Gold Award symbol For a nice example of using Quick Mask mode to improve a Selection that was started using the Magnetic Lasso tool, go here.

Picture of Quick Mask buttons Finally, a suggestion: make sure that you leave the Quick Mask button in the default state if you change it, before exiting Quick Mask mode, otherwise you really will get confused.

Channels and the Channel Mixer

Introduction to Channels

Channels Palette You access Channels using the Channels Palette, (which you may notice I have grouped with the Layers Palette).

There are two types of Channel shown here:

  1. RGB Colour Channels (the top 4 in this Palette)
  2. Mask Channels (the bottom 3 in this Palette).

You can turn a Channel's visibility on and off, and select a Channel to work with, in exactly the same way as you do for Layers using the Layers Palette.

You can delete or duplicate any individual Channel. I recommend using a context‑sensitive menu for this purpose.

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RGB Colour Channels

RBG colour channels RGB Channels (like CMYK and Lab Colour Channels) are stored in Photoshop as grey-scale images.

The Channel called RGB (Ctrl+~) doesn't actually exist. It is a quick way of selecting all of the individual Red, Green and Blue Channels (Ctrl+1Ctrl+2Ctrl+3).

You can't delete or duplicate the RGB Channel, since it isn't a real Channel, although you can delete or duplicate individual colour Channels.

You rarely want to delete one of the RGB colour channels. You are more likely to use the Channel Mixer instead, see below.

You might well want to duplicate a colour Channel, in order to modify the duplicate and then use it as a Mask.

You will find more information about working with Colour Channels elsewhere in this Guide, in the sections Adjusting Levels, Adjusting Curves, and Useful techniques and work flows.

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Mask Channels (a.k.a. Alpha Channels)

Picture of Layers with Mask Mask Channels are often referred to as Alpha Channels.

You will find information about Mask Channels and their uses elsewhere in this guide, in the section on Selections and Masks.

Click the image to visit that section.

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The Channel Mixer

Channel Mixer You can use this tool to replace a Colour Channel with a mixture of the existing Colour Channels, as shown here. This example comes from the Red-eye reduction technique described later in this guide.

Alternatively, you can tick the Monochrome box, in which case all three Colour Channels will end up with the same value from the mix of Source Channels that you specify (mouse-over the image to see an example of using the Monochrome option), and you will end up with an image containing only grey values.

An example of doing this will be found in the section Converting a colour image to black & white or monochrome later in this guide.

The Constant slider is yet another way of varying the overall brightness of your image. I don't use it, at least not yet.

For reasons that should be familiar by now, I recommend that you invoke this tool via an Adjustment Layer, using Layer > New Adjustment Layer > Channel Mixer.

  • Tip
  • Picture of Light Bulb It is usually best to make sure that the contributions from each Colour Channel add up to 100% (in this case 0% Red, 50% Green, 50% Blue).
  • Make that your starting point, anyway.

  • Which colour spaces can I use the Channel Mixer with?
  • This tool is commonly used with RGB or CMYK colour spaces.
  • It can't be used with Lab colour, simply because that colour space doesn't have component colour channels.

Click the image, or go here, for more information on this tool.

Adjusting Levels

The Levels Tool

The Levels tool (like the Curves tool, described below) is used to improve the brightness, contrast and tonal range of the picture.

I tend to use the Levels tool for initial adjustments, and the Curves tool for later improvements.

  • Short Version
  • There's a quick way (often very effective) to improve your image. Just alt-drag the outer two Input Levels sliders inwards until pixels start to appear. If the contrast of these pixels matters in the final image, then stop - you're done!
  • You can also adjust overall brightness using the middle Input Levels slider.
  • If you want to understand what's going on, and get the best results, there's a bit more...

Levels curve The Levels tool shows you (as a histogram) the relative numbers of pixels in your image at different levels of brightness, from no brightness on the left to full brightness on the right.

It can do this either for all the colour channels together (as shown here) or for individual colour channels.

I have learnt that it is best not to adjust levels on the original image. Instead, I create an Adjustment Layer for using the Levels tool, using Layer > New Adjustment Layer > Levels.

Gold Award symbol For an excellent tutorial on the Levels tool from Cambridge in Colour, go here (or click the above image).

The following notes may also be useful.

Levels curve The Levels tool includes the following:

Picture of Light Bulb Also, if you press the Alt key, the Cancel button will change to a Reset button. This is a useful way of cancelling your changes without leaving the tool.

In what follows, there are several references to the Curves tool, described below, which is another way of working with the same information.

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Input Levels sliders

Picture of sliders Left to right, these are the Input Shadow, Brightness and Input Highlight sliders.

The horizontal axis on the Curves graph shows the original input values, the vertical axis shows the corresponding output values.

(You don't actually see this graph when you are working with the Levels tool, but it shows what is actually happening.)

Pulling the outer two Input Levels sliders on the Levels tool inwards has the effect of increasing the slope of the Curves graph by pulling its ends inwards, as shown here (mouse-over to see original graph).

You normally move your sliders to where your image contains no, or very few, pixels which are darker than the left-hand slider's position or brighter than the right-hand slider's position. The red arrows on the above diagram show the range of brightness values falling between the new positions of the two sliders on the Levels tool.

You can see that for all the "useful" brightness values in your original (input) image, you now have a full range of pixel values in the modified (output) image. The steeper slope also indicates greater contrast throughout your image.

Pulling the middle (brightness) slider to the right has the effect of changing the shape of the Curves graph as shown here. The effect is to darken the image and to change its contrast in a variable way. (Mouse-over to see the opposite effect when you move the Brightness slider to the left, which brightens the image and also changes its contrast in a variable way.)

(Again, you don't actually see this graph when you are working with the Levels tool, but it shows what is actually happening.)

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Deciding where to set the Input Levels sliders

Picture of Light BulbThe technique I use most often is to locate where the darkest and lightest pixels in my image are, by alt-dragging the outer two sliders inwards, instead of just dragging them.

Using the Alt (or Option) key when moving the outer sliders puts the Levels tool temporarily into threshold mode. In this mode, as you move the left-hand slider to the right the display is initially white, and you only see pixels appearing when their brightness level reaches the threshold corresponding to where the slider now is. The darkest pixels will therefore appear first, and you will also see where they occur in the image. When this happens, and if the contrast of these first pixels is important, then this is a good place to leave the slider.

You do a similar thing when moving the right-hand slider to the left, which starts with an initially black display and will then find the brightest pixels in your image.

An alternative method of setting the sliders is to use the various Eyedroppers, see below.

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Output Levels sliders

  • Short Version
  • Use these only if you want to reduce the overall contrast.
Sliders These sliders have the effect of constraining the adjusted image (the output) to a range of values, reducing its contrast.

The corresponding effect on the Curves graph might look like this (mouse-over to see original graph).

The output values, which run vertically on the graph, are now limited to a range of values, and the slope of the graph is reduced.

(Again, you don't actually see this graph when you are working with the Levels tool, but it shows what is actually happening.)

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Eyedroppers (for setting Input Levels sliders and Colour Samplers)

eyedroppers Left to right, these are the Shadow, Midtone and Highlight Eyedroppers. If you look carefully, they appear to be filled with black, grey and white ink!

  • Short Version
  • The Eyedroppers are used to set Input Levels sliders and Colour Samplers.
  • The Shadow and Highlight Eyedroppers are only useful for setting sliders if the darkest or brightest points in your image that contain any detail are in a neutral colour.
  • Otherwise it is better to set the corresponding sliders individually for each of the RGB channels.
  • I have not yet found a good use for the Midtone Eyedropper.
info palette If you select any one of the Eyedroppers and hover over the image, but don't click, you will find (not surprisingly) that your current tool is now the Eyedropper tool, and colour information corresponding to where the mouse is will continuously appear in the Info Palette.

You will notice two sets of numbers for each value. These are the values before and after your current Levels adjustment is applied.

If you select one of the Eyedroppers and click the image, then you will set the corresponding slider to the values at that position.

It is generally best to set some Colour Samplers (points) first, at least for Shadows and Highlights:

  1. You first locate the areas containing the darkest and lightest areas (using thresholds described above).
  2. Then you locate the best points within those areas using the Eyedropper tool and the Info Palette.
  3. Info palette with color sampler values Then you shift-click each point to add the Colour Sampler to the image, with the corresponding values now appearing permanently (until you delete the sampler) on the Info Palette.

Any subsequent Levels adjustments (or any other adjustments) that you make will now be reflected in the Colour Sampler values on the Info Palette.

  • You can use this to check for colour casts. Colours that are supposed to be black, white or a shade of grey should have equal, or very similar, values for each of the R, G and B channels.

Now you can select the appropriate Levels Eyedropper, place it exactly over the Colour Sampler you did earlier (the tool outline will turn white when you're exactly in position), and click to set the slider.

Picture of Light Bulb A pop quiz: How do you delete a Colour Sampler?

  1. The logic of the modifier keys might suggest to you that since Shift‑Clicking sets a point, then Alt-Shift-Clicking the same point will remove it. If it did, then you were right!
  2. In order to easily delete all the Colour Samplers, you need to have selected the Colour Sampler tool (underneath the main Eyedropper tool). If necessary, use Shift+I to cycle through the various Eyedropper tools until you see the Clear button appear on the Tool Option Bar. If you have just placed some Colour Samplers, then this tool may already be selected. Press the Clear button!

You can also hide the Colour Samplers (if you are using a tool where you can see them in the first place) using Ctrl+H, which is a shortcut that works with other things, e.g. the "marching ants" when you have made a Selection somewhere. Hiding doesn't remove them from the Info Palette, though.

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Channel selector

RGB If you are working with RGB colour, the Levels tool either lets you work on all three colour channels simultaneously, as shown here, or else you can work with each colour channel individually using the pick list (mouse-over to see an example).

  • Short Version
  • Working with individual colour channels for Levels may be useful when you are checking for, and correcting, colour casts.

For more information about working with individual channels, see the Useful techniques and work flows section below.

  • Advanced Stuff
  • If you are working with Lab Colour instead of RGB Colour, then you get different choices here (Lightness, a, b instead of RGB, Red, Green, Blue).
  • When working with Lab Colour some of your Photoshop functions disappear, for example the alt-drag option when using the Input Levels sliders.
  • It might be useful to work with a histogram for the Lightness channel. I am not sure about the a and b channels. Lab Colour is interesting (see here) and I may look into it more in the future.

Adjusting Curves

The Curves tool

The Curves tool (like the Levels tool, described above) is used to improve the brightness, contrast and tonal range of the picture.

I tend to use the Levels tool for initial adjustments, and the Curves tool for later improvements.

Working with Curves, I often use a Mask or Selection to limit the area of the image where the adjustment has any effect.

  • A suggestion...
  • Before continuing here, you may find it useful to read about the Levels tool, if you haven't done so already.
  • The two tools have a lot in common.

Curves graph From Photoshop Help:

"Like the Levels dialog box, the Curves dialog box lets you adjust the entire tonal range of an image. But instead of making adjustments using only three variables (highlights, shadows, midtones), with Curves you can adjust any point along a 0-255 scale while keeping up to 15 other values constant. You can also use Curves to make precise adjustments to individual color channels in an image."

I have learnt that it is best not to adjust curves on the original image. Instead, I create an Adjustment Layer for using the Curves tool, using Layer > New Adjustment Layer > Curves.

Gold Award symbol For an excellent tutorial on the Curves tool from Cambridge in Colour, go here (or click the above image).

The following notes may also be useful.

Curves graph The things I needed to know about this tool were:

  1. What the different shapes of curves mean
  2. How to change the shape of a curve
  3. Deciding where to change the shape of a curve
  4. Saving and restoring useful curves
  5. How and when to work with individual colour channels

These are described below.

  • Features that I don't use (and why)
  • Eyedroppers and pencil tool I don't use the Eyedroppers - at least, not with Curves. That's because I find it much better to use the Levels Eyedroppers, when I use Eyedroppers at all. In the Levels tool, the effect can be seen immediately on the histogram. In the Curves tool, the image changes but there is no effect on the Curves graph.

    The Pencil tool (and the Smooth button) are used for drawing free-form curves. I find it much easier to use the normal method for getting the shapes that I want.

What the different shapes of curves mean

A very good description of what the Curves graph is really doing can be found in this tutorial.

The Curves graph shows how different brightness values of any pixel in the original image (the horizontal axis of the graph) get transformed into adjusted brightness values (the vertical axis of the graph). A straight line from bottom-left to top-right would represent "no adjustment".

S-curves Two common curve shapes are the S-curve (shown here) which adds contrast to the midtones at the expense of shadows and highlights, and the inverted S-curve (mouse-over to view) which does the opposite.

Click the image for a full explanation from the Cambridge in Colour tutorial.

  • The best of all worlds...
  • The really great thing about using Adjustment Layers is that you don't have to choose which improvement you really want - you can have both. You can use one curve, in one Adjustment Layer, to fix the midtones (say), and another curve, in another Adjustment Layer, to fix the shadows and highlights (say). Each Adjustment Layer can have its own Mask, which limits the area to which the adjustment is applied.

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How to change the shape of a curve

The basic technique is pretty simple: you click a point on the curve and drag it, or click near the curve and the curve will bend to pick up the new point where you clicked. The new point is an anchor point, which is created if it wasn't there already.

You can place up to 15 other points (anchor points) on the curve. When you move an anchor point, the curve bends smoothly in such a way that it still passes through any existing anchor points.

Numbers on curves graph You can also move a point on the curve by clicking that point and then entering numbers.

Picture of Light BulbA really useful way to change numbers by small amounts (which works everywhere in Photoshop) is to use the up and down arrows, which change the selected number by plus or minus 1.

Use the Shift key as well to change the selected number by plus or minus 10.

Selected points Using the Shift key you can place or select multiple anchor points on a graph (they turn solid black), and then if you move one of them, you move them all as a group (mouse-over to see an example).

You can deselect all the points by using Ctrl+D, which is the general Photoshop shortcut for cancelling selections. Or you can shift-click an individual point to deselect it.

GridsSometimes you may want to change from the default 4 x 4 grid to a finer 10 x 10 grid, as an aid to placing points accurately (mouse-over to see the difference).

In order to switch between the two grids, alt-click anywhere on the graph.

For the same reason, you may want to increase the size of the whole dialog box. How you do this depends on your version of Photoshop. In my case, there is a small icon in the bottom right-hand corner of the dialog box that you can click, as you can see here.

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Deciding where to change the shape of a curve

You will often want to change the curve in a region that corresponds with an area of particular lightness or colour on your image.

Curve with moving circle That's easy. All you have to do is to move your mouse over that area of the image with the mouse key pressed, and you will see a moving circle on the graph running up and down a small distance of the graph. That's the section of the graph you may want to change.

It gets even easier. When you have moved the mouse so that the moving circle is in the approximate middle of its travel, Ctrl-click the mouse on the image to set an anchor point on that part of the graph. You can now drag this point, or adjust it using the numbers.

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Some useful curves to save and restore

Load and save buttons You can save and restore curves (with any anchor points) that you may find useful. When you save a curve you should give it a meaningful name and choose where in your filing system it should be placed.

  • Note
  • RGB A curve belongs to the Channel (e.g. RGB or Red, Green or Blue) for which it was created.
  • If you save a curve from (say) the Red channel and are later working on the RGB composite channel, and you then reload the saved Red channel curve, you won't see it unless you switch from the RGB to the Red channel.

Lockdown curves One of the most useful curves to save and re-use is a lockdown curve. The one shown here places anchor points at intersections of the 10 x 10 grid. This allows you to make small adjustments to part of the curve without affecting the rest of the curve (mouse-over for an example).

You have to create such curves yourself and save them (unless someone has done it for you). Remember that you may need several such curves if you work with several Channels.

You may find it useful to use numbers and arrow keys to place the anchor points accurately, as described above.

  • Helpful Note:
  • The co-ordinates (both input and output) for the 10*10 grid lockdown curve anchor points shown here are 25, 50, 76, 101, 127, 152, 178, 203, 229.

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How and when to work with individual colour channels

The Curves tool can be used to remove colour casts and to adjust hue, saturation and lightness for individual colour channels, offering more control than is possible with the Hue/Saturation Adjustment tool.

RGB You select which Channel to work on in the same way as you did for Levels.

For more information about working with individual channels, see the Useful techniques and work flows section below.

Using Layers

Introduction to Layers

Layers

The effective use of Layers is fundamental to the effective use of Photoshop (and other programs featuring Layers, such as Paint Shop Pro).

Layers are images (including areas of colour or patterns) and adjustments (see below) that overlay each other.

The default situation is that a layer hides the layers underneath it... and you may well ask: "What use is that?"

The answer would be: "Not a lot!" were it not for the various ways in which a Layer can be "mixed" with the Layer below:

  1. Adjustment layer A Layer can be an Adjustment Layer. This kind of Layer produces an adjustment to all the Layers below it (for example, a change of contrast, hue or saturation).

    It is actually only the adjustment (a set of mathematical formulae, if you like), and not a new set of RGB channels, that is stored in this Layer. The original Layer is unchanged. Adjustment Layers are described further below.
  2. Mask A Layer can have a Mask with transparent areas. The transparent areas of the Mask are where lower Layers can "show through" - in this Layer, anything in the transparent (black) area of the Mask is effectively invisible, or has no effect.
  3. Blend mode and opacity The Blend Mode of the whole Layer can be changed from Normal (no blend) to some other Blend Mode (mouse-over the image to the right for an example).
    • This will produce an image which is a blend of this Layer and the Layer below it, with different Modes producing different results. Blend Modes are a powerful feature of Photoshop, described here in this guide.
  4. Blend mode and opacityThe opacity of the whole layer can be reduced, allowing the lower Layers to "show through" and reducing the effect of this Layer (mouse-over for an example).
  5. Gradient fill The top Layer can contain an image with areas of complete or partial transparency, for example it could be created with a Gradient Fill shading from a foreground colour to transparency.
  6. Methods 1. to 4. above can also be used in any combination, as can methods 2. to 5., giving rise to a bewildering variety of possibilities!

Movie camera icon Gold Award symbol One of the best introductions to these ideas that I have found are Andy Heatwole's free online videos, where you can see many of these ideas in action.

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The Background Layer

The Background Layer (the italics are generally used to indicate its special nature) is created when you open an image file (such as a TIFF or JPEG file) that doesn't have layers.

Background layers The Background Layer has differences from other kinds of Layers. The basic reason is simple: there is no other Layer beneath it. You therefore can't make transparent regions in it (if you delete or clear a selection it will fill with the background colour), and you can't move any other Layer below it.

What you can do is to convert it to a normal Layer and give it another name, which you do by double-clicking its icon (mouse-over the image to see the difference if you do this - note the difference to the greyed-out options). You can now treat it like any other Layer.

It can also be a good idea to duplicate the Background Layer (how? see my tip on context-sensitive menus), especially if otherwise you were going to directly modify its pixels (as distinct from using an Adjustment Layer). You will find some reasons for doing this here.

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Adjustment Layers

Adjustment choices Here is a list of tools that you should consider creating an Adjustment Layer for, rather than changing an image directly.

The use of Adjustment Layers was introduced in my Basic Work Flow, with a little more explanation in the Introduction to Layers above.

I prefer to create an Adjustment Layer using Layer > New Adjustment Layer (which then offers the choices shown to the right), as this way of doing it provides options for the initial setting of the Layer's Mask.

See also my notes on Creating a new Layer later in this section.

The use of Adjustment Layers has the following major advantages:

  1. Adjustment Layer The various adjustments that you make to an image, if done using separate Adjustment Layers, do not lose colour information from the original image.
  2. If you change your mind, you can go back and re-run a particular Adjustment. To do this, you can either click the icon for the tool to change the adjustment settings, or edit the Layer's Mask in order to change the scope of the effect, or both.
  3. Unlike going back many steps via the (extremely useful) History Palette, revisiting an Adjustment does not remove all the other steps you did with this document since you made that Adjustment.
  4. You can turn the visibility (and hence the effect) of the Layer on and off - more about that here.

Finally, it is worth mentioning that Adjustment Layers are efficient in memory. Photoshop does not store the adjusted pixels as a new image. Instead, it only stores the settings that the Adjustment tool uses. Using many Adjustment Layers will not give you huge document files!

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Changing the stacking order of Layers

This is really easy. You just click and drag any Layer (other than the Background Layer) up or down in the Layers Palette.

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Changing the visibility of a Layer

eye symbols for visibility You can turn the visibility of a Layer on and off by clicking its Eye symbol in the left-hand column of the Layers Palette (mouse-over for an example).

The effect of a Layer disappears when it is not visible, so this is a valuable way of turning (say) an Adjustment Layer on and off in order to compare the effect with and without it.

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Creating a new Layer

  • Stop!
  • The new Layer will be created just above the active Layer (the layer that is currently highlighted). Make sure this is where you want the new Layer to go!
  • If necessary, click another Layer to activate it.

My preferred ways of creating a new Layer are:

  • Starting from scratch, use Layer > New > Layer, or
    Layer > New Adjustment Layer > ..., or Layer > New Fill Layer > ....
    • These give you useful options, which some other methods don't.
  • Starting from an existing image, use the Move tool (V). Click the document window or Layer for the image that you want to start from, then drag the tool's cursor onto the document window containing the image you are moving to.
    • Give the new Layer a meaningful name by double-clicking it.
    • Use the Shift key if you want to center the new Layer.

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Creating a Layer Mask

Picture of Layers with Mask There are many ways of creating a Mask for a Layer.

You will find these described here in my section Selections and Masks (or click the image).

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Why and how you can link Layers, and create Layer Sets

  • Short Version
  • You link Layers together if you want to move or scale them as a group, or if you want to align them or distribute them evenly, or if you want to collapse them into a Layer Set for convenience.

Link symbols in layers You link Layers together by clicking in the second column of the Layer Palette, where the "link" symbol will appear (mouse-over the image for an example of doing this).

You first activate (select) one of the layers, and then place a "link" symbol in each other Layer (usually but not necessarily adjacent to the active Layer) that you want to be linked with this one. You have then created what I will call a linked layer collection.

  • Notes:
    1. I don't want to use the word "group" here, because grouping layers is something different... see below.
    2. You don't see the "link" symbol in the active Layer until you select one of the other Layers in the same linked layer collection.
    3. New versions of Photoshop may deal with linking slightly differently - see here for details.

If you activate any one of the Layers in a linked layer collection, then you will see all of the related "link symbols" appear. Any moving or scaling operation you perform with the active Layer will be performed on all of the linked layer collection.

  • Gotcha!
  • If you activate a Layer, and can see other Layers linked to it, you might reasonably expect that the Move tool will allow you drag these layers to another document window and drop them there.
  • Nope! Instead, you have to set up these Layers as just described, and then use the Move tool to drag from your document window to the other document window. Then it works.

Align symbols When you have a Layer selected and one other Layer in the linked layer collection, then the Move tool's Options Bar will show you the alignment buttons, with the distribution buttons greyed-out.

  • You need to have at least 3 things to work with before you can distribute them!

Align symbols When you add at least one more Layer to the linked layer collection, the distribution options also become available.

The options for alignment and distribution will be familiar to you if you use drawing programs such as Visio. You can find out more about these options here.

The thing to remember here is that the active (selected) Layer becomes the reference for alignment and distribution. The other linked Layer(s) are aligned or distributed evenly with respect to the reference.

  • Layer Sets
  • Layer Sets are useful only if you have many Layers and they fall into logical groups, for example a group that makes general adjustments to an image, and a group that fixes colours using masks or selections.
Layer Sets are a convenience that allow you to collapse a linked layer collection into a single Layer. You can then do things like locking, or turning the visibility on and off for the whole Layer Set.

More information about Layer Sets will be found here.

 

P.S. Here is something that you may find useful if you are working with images in different documents:

  • A tip from Sue Chastain:
  • Picture of Light Bulb"If you are in the new document dialog box and you want your new document to be the same dimensions as another document that is currently open, you can go to the window menu and choose the open document and the numbers in the new document dialog will adjust themselves automatically! This handy little trick works in the image size and canvas size dialog boxes too. Try it out!"
  •     —from her tutorial on Moving, Copying & Transforming Layers

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Why and how you can group Layers

  • Short Version
  • Layers can form a transparency sharing group if you want to share the transparency of one Layer in one or more Layers above it.

When Photoshop talks about "grouping Layers", this may confuse you since Photoshop also talks about "linking Layers", which was discussed in the previous section.

I use the term transparency sharing group because "group" is ambiguous. See the note below.

Grouped layers In the image to the right, the Adjustment Layer "Hard Light" is sharing the transparency of "Curves 1", the Layer below it. In this case the transparency is coming from Curve 1's Layer Mask.

"Hard Light" is a Gradient Fill Adjustment Layer, which I gave this name because it uses Blend Mode Hard Light.

Since I only want this Gradient Fill applied in an area where the "Curves 1" mask is, I want the "Curves 1" Mask to act as a "Clipping Mask".

In the image above, the bent arrow indicates that Layer "Hard Light" is using a lower Layer's Clipping Mask. I could have had several such Layers, each with a bent arrow pointing downwards.

The underlining in Curves 1 indicates that this is where the Clipping Mask is.

As usual, there are many ways to "group" a Layer with the one beneath it.

Group box ticked The easiest way, if you think about it at the time, is simply to tick the box when you create a new Layer, as shown here.

Otherwise, select the chosen Layer and use Layer > Group With Previous (Ctrl+G), or alt-click the boundary between the chosen Layer and the one below.

  • Note:
  • It's important to understand that it's really the transparency of the bottom layer that is being reused.

    The bottom layer will often get this transparency from its Mask (in which case that's a Clipping Mask), but there are other ways of getting transparency into a Layer, including using a Clipping Path, or deleting a Selection on a Layer that doesn't have the Lock Transparency option selected (see below).

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Why and how you can lock Layers and Layer Sets

  • Short Version
  • The "lock layer" options prevents accidental mistakes when you are doing complex stuff.
  • They are most useful where multiple images are being used in various Layers and Masks, particularly if these must line up exactly.

You can lock a Layer (except the Background Layer), or you can lock a Layer Set, using buttons on the Layers Palette.

In left to right order, the buttons do this:

  1. Lock symbols Lock Transparency: confine editing to the opaque portions of the Layer (but you can still paint anywhere on the Layer's Mask, if there is one, and this may change the Layer's transparency).
  2. Lock Image: prevent any modification of the layer's pixels using the painting tools (but you can still paint anywhere on the Mask, if there is one).
  3. Lock Position: prevent the layer's pixels (including Mask pixels) from being accidentally moved.
  4. Lock All: prevents any change to the Layer's pixels or to its Mask (the safe option).

The Layer's thumbnail will show a grey or black "lock" symbol if it is partially or completely locked.

  • Notes:
    1. The first lock option will allow you to paint on the Layer in places where the Layer's Mask is providing transparency.
    2. The first two lock options are not available for Adjustment Layers, which don't store any pixels (the Layer's Mask is stored in a Mask Channel).
    3. A locked Layer can still be moved up and down the stack of Layers.

 

 

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