Adobe® Photoshop® CS3 Classroom in a Book

Chapter 6. Masks and Channels
Table of Contents
Chapter 6. Masks and Channels................................................................... 1
Working with Masks and Channels................................................................................................................................................ 3
Getting Started................................................................................................................................................................................ 3
Creating a Quick Mask.................................................................................................................................................................... 5
Editing a Quick Mask...................................................................................................................................................................... 8
Saving a Selection as a Mask.......................................................................................................................................................... 11
Viewing Channels.......................................................................................................................................................................... 14
Adjusting Individual Channels...................................................................................................................................................... 16
Loading a Mask as a Selection....................................................................................................................................................... 17
Applying Filters to a Mask............................................................................................................................................................ 20
Applying Effects Using a Gradient Mask...................................................................................................................................... 20
Resizing the Canvas...................................................................................................................................................................... 22
Extracting the Paper Texture........................................................................................................................................................ 23
Moving Layers Between Documents............................................................................................................................................. 27
Colorizing with an Adjustment Layer........................................................................................................................................... 28
Grouping and Clipping Layers...................................................................................................................................................... 30
Applying a Mask from a Saved Selection...................................................................................................................................... 32
Using Type as a Mask.................................................................................................................................................................... 33
Review........................................................................................................................................................................................... 38
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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Adobe Photoshop uses masks to
isolate and manipulate specific parts
of an image. A mask is like a stencil.
The cutout portion of the mask can
be altered, but the area surrounding
the cutout is protected from change.
You can create a temporary mask for
one-time use, or you can save masks
for repeated use.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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6 Masks and Channels
Lesson overview
In this lesson, you’ll learn how to do the following:
Licensed by
Hal Peterson
• Refine a selection using a quick mask.
• Save a selection as a channel mask.
• View a mask using the Channels palette.
• Load a saved mask.
• Apply filters, effects, and blend modes to a mask.
• Move an image within a mask.
• Create a layer mask.
• Paint in a mask to modify a selection.
• Make an intricate selection using the Extract feature.
• Create and use a gradient mask.
• Isolate a channel to make specific image corrections.
• Create a high-quality grayscale image by mixing channels.
This lesson will take about 90 minutes to complete. If needed, remove the
previous lesson folder from your hard drive, and copy the Lesson06 folder
onto it. As you work on this lesson, you’ll preserve the start files. If you
need to restore the start files, copy them from the Adobe Photoshop CS3
Classroom in a Book CD.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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174 LESSON 6
Masks and Channels
Working with masks and channels
Photoshop masks isolate and protect parts of an image, just like masking tape prevents a
house painter from getting paint on the window glass or trim. When you create a mask
based on a selection, the area not selected is masked, or protected from editing. With
masks, you can create and save time-consuming selections and then use them again.
In addition, you can use masks for other complex editing tasks—for example, to apply
color changes or filter effects to an image.
In Adobe Photoshop, you can make temporary masks, called quick masks, or you
can create permanent masks and store them as special grayscale channels called
alpha channels. Photoshop also uses channels to store an image’s color information
and information about spot color. Unlike layers, channels do not print. You use the
Channels palette to view and work with alpha channels.
A key concept in masking is that black hides, white reveals. As in life, rarely is anything
black and white. So: shades of gray partially hide, depending on the gray levels (255
equals black (hidden), 0 equals white (revealed)).
Getting started
You’ll start the lesson by viewing the finished image that you’ll create using masks
and channels.
1 Start Photoshop and then immediately hold down Ctrl+Alt+Shift (Windows) or
Command+Option+Shift (Mac OS) to restore the default preferences. (See “Restoring
default preferences” on page 6.)
2 When prompted, click Yes to confirm that you want to reset preferences, and Close
to close the Welcome Screen.
3 Click the Go To Bridge button ( ) in the tool options bar to open Adobe Bridge.
4 Click the Folders tab on the left side of the Bridge window. Browse to the Lessons
folder where you copied the Adobe Photoshop CS3 Classroom in a Book lesson files, and
select the folder.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 175
Classroom in a Book
5 Choose File > Add To Favorites to add the Lessons folder to the Favorites panel on
the left side of Bridge. If the folder already appears in Favorites panel, the menu item
will read “Remove From Favorites,” and you can skip this step.
Besides accessing folders and files from the Folder panel, you can add and retrieve
them as favorites. You can also add favorite items from the Content panel. The Favorites
panel lets you add icons for project files, folders, applications, and other assets you use
frequently, to quickly locate them.
6 In the Favorites panel on the left side of Bridge, click the Lessons favorite, and then
double-click the Lesson06 folder in the thumbnail preview area.
7 Select the 06End.psd file so that it appears in the center Content panel, and study
its contents.
Your goal in this lesson is to create a book cover titled “Zen Garden.” You will use several
photos—a Buddha statue, a Japanese temple, a bamboo fence—and embossed text, and
then create masks to combine the photos into one image. You’ll also make intricate
selections of the ripped edges of paper that will serve as the composition’s background.
Your final touch will be to add type to the cover that reveals the paper texture.
8 Double-click the 06Start.psd thumbnail to open it in Photoshop.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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176 LESSON 6
Masks and Channels
Creating a quick mask
You’ll begin the lesson by using Quick Mask mode to convert a selection border into a
temporary mask. Later, you will convert this temporary quick mask back into a selection
border. Unless you save a quick mask as a more permanent alpha-channel mask, the
temporary mask will be discarded once it is converted to a selection.
1 Choose File > Save As, rename the file as 06Working.psd, and click Save. Click OK if
a compatibility warning appears.
Saving another version of the Start file lets you return to the original if you need it.
You’ll mask the Buddha statue so that you can separate it from its background and paste
it in front of a new background.
2 In the Layers palette, click the Buddha layer name to select the layer.
3 Click the Quick Mask Mode button (
working in Standard mode.)
) in the toolbox. (By default, you have been
A
B
A. Standard mode
B. Change Screen mode
In Quick Mask mode, a red overlay appears as you make a selection, masking and
protecting the area outside the selection the way that a rubylith, or red acetate, masked
images in traditional print shops. You can apply changes only to the unprotected area
that is visible and selected. Notice, too, that the selected layer in the Layers palette
appears gray, indicating you are in Quick Mask mode.
4 In the toolbox, select the Brush tool ( ).
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 177
Classroom in a Book
5 In the tool options bar, make sure that the mode is Normal. Then, click the arrow
to display the Brushes pop-up palette, and select a large soft brush with a diameter of
65 pixels. Click off the palette to close it.
You’ll use this large brush to rough out a mask, and refine it in the next exercise.
6 In the image, drag the Brush tool to paint a mask around the halo; the brush
size should match the width of the halo. A red overlay appears wherever you paint,
indicating the mask you’re creating.
In Quick Mask mode, Photoshop automatically defaults to Grayscale mode, with a
foreground color of black, and a background color of white. When using a painting or
editing tool in Quick Mask mode, keep these principles in mind:
• Painting with black adds to the mask (the red overlay) and decreases the selected area.
• Painting with white erases the mask (the red overlay) and increases the selected area.
• Painting with gray partially adds to the mask.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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178 LESSON 6
Masks and Channels
7 Continue painting with the Brush tool to add the Buddha statue to the mask. Don’t
include the background.
Don’t worry if you paint outside the outline of the statue. You’ll fine-tune the mask in
the next exercise.
8 In the Layers palette group, click the Channels tab to bring that palette forward, or
choose Window > Channels. If necessary, expand the palette by dragging its lower right
corner so that you can see all of it.
In the Channels palette, the default color-information channels are listed—a full-color
preview channel for the CMYK image and separate channels for cyan, magenta, yellow,
and black.
Note: To hide and display individual color channels, click the eye icons ( ) in the Channels
palette. When the CMYK channel is visible, eye icons also appear for all four individual
channels, and vice versa. If you hide an individual channel, the eye icon for the composite
(the CMYK channel) also disappears.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 179
Classroom in a Book
9 In the Channels palette, notice that this quick mask appears as a new alpha channel,
named QuickMask. Remember, this channel is temporary: unless you save it as a
selection, the quick mask will disappear as soon as you deselect.
Editing a quick mask
Next, you will refine the selection of the statue by adding to or erasing parts of the
masked area. You’ll continue to use the Brush tool to make changes to your quick mask.
The advantage of editing your selection as a mask is that you can use almost any tool or
filter to modify the mask. (You can even use selection tools.)
Adding to a selection by erasing masked areas
You will continue to work in Quick Mask mode. In Quick Mask mode, you do all of
your editing in the image window.
1 In the tool options bar, select a smaller soft brush of 45 pixels in diameter from the
Brushes pop-up menu.
You’ll switch brushes several times during this lesson. For convenience, to quickly
display brush choices, click the Brushes palette icon ( ) in the upper right corner of
your screen to open the palette. To collapse the palette to an icon, click the doublearrow ( ) in the upper right corner of the palette.
2 Click the Switch Foreground And Background Colors button ( ) above the foreground
and background color-selection boxes. To erase the mask, you paint with white.
3 Using the keyboard shortcuts, press Spacebar+Ctrl (Windows) or
Spacebar+Command (Mac OS), and zoom in on the Buddha’s halo.
4 Brush out any tree detail that may appear at the edge of the statue.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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180 LESSON 6
Masks and Channels
Julieanne Kost is an official Adobe Photoshop evangelist.
TOOL TIPS FROM THE PHOTOSHOP E VANGELIST
Zoom tool shortcuts
Often when you are editing an image, you’ll need to zoom in to work on a detail and then zoom
out again to see the changes in context. Here are several keyboard shortcuts that make the
zooming even faster and easier to do.
• Press Ctrl+spacebar (Windows) or Command+spacebar (Mac OS) to temporarily select the
Zoom In tool from the keyboard. When you finish zooming, release the keys to return to the tool
you were previously using.
• Press Alt+spacebar (Windows) or Option+spacebar (Mac OS) to temporarily select the Zoom
Out tool from the keyboard. When you finish zooming, release the keys to return to the tool you
were using.
• In the toolbox, double-click the Zoom tool to return the image to 100% view.
• Hold down Alt (Windows) or Option (Mac OS) to change the Zoom In tool to the Zoom Out tool,
and click the area of the image you want to reduce. Each Alt/Option-click reduces the image by
the next preset increment.
• With any tool selected, press Ctrl+plus (Windows) or Command+plus (Mac OS) to zoom in, or
press Ctrl+minus or Command+minus to zoom out.
5 If you make a mistake and brush out part of the statue, click the Switch Foreground
and Background Colors button ( ) above the foreground and background colorselection boxes. Then repaint any needed detail.
Shortcut: Press X to switch the foreground color to white and the background color
to black, and vice versa.
6 Continue brushing along edges that are too soft or missing detail until you are
satisfied with the results.
7 Click the Quick Mask Mode button ( ) in the toolbox to switch to Standard mode
and see how painting in the mask alters the selected area. Notice that the selection
border increases to encompass more of the statue.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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Page 10
ADOBE PHOTOSHOP CS3 181
Classroom in a Book
For a cleaner edge, use a hard-edge, smaller brush and continue adding to and
subtracting from the image until the edge is well defined. Or use the Eraser tool to
remove any excess selection.
Editing mask in Standard mode
Quick Mask selection
If any areas within the statue still appear to be selected, it means that you haven’t erased
all of the mask. You’ll continue to refine the mask in the next steps.
Subtracting from a selection by adding masked areas
If you have erased the mask beyond the edges of the statue, part of the background will
be included in the selection. You’ll fix these flaws by returning to Quick Mask mode and
restoring the mask to those edge areas by painting with black.
1 Click the Quick Mask Mode button (
) to return to Quick Mask mode.
2 Press X to switch the foreground and background colors so that the black color
swatch appears on top. Remember that in the image window, painting with black will
add to the red overlay.
3 Choose a small, hard-edged brush, such as 9 or 13 pixels, from the Brushes
pop-up palette.
4 Paint with black to restore the mask (the red overlay) to any of the background area
that is still unprotected. Continue working until only the area inside the statue remains
unmasked and you are completely satisfied with your mask selection.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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182 LESSON 6
Masks and Channels
Remember that you can zoom in and out as you work. You can also switch back and
forth between Standard mode and Quick Mask mode.
Note: In Quick Mask mode, you can also use the Eraser tool to remove any excess selection.
Painting with black to restore mask
5 In the toolbox, click the Quick Mask button (
view your final statue selection.
) to return to Standard mode and
6 Double-click the Hand tool ( ) to make the statue image fit in the window.
Saving a selection as a mask
Quick masks are temporary. They disappear as soon as you deselect. However, you can
save a selection as an alpha-channel mask so that your time-consuming work won’t be
lost, and you can reuse the selection in this work session or a later one. You can even use
alpha channels in other Photoshop image files.
To avoid confusing channels and layers, think of channels as containing an image’s color
and selection information; think of layers as containing painting and effects.
Note: If you save and close a file while in Quick Mask mode, the quick mask will show in
its own channel the next time you open the file. If, however, you save and close your file
while in Standard mode, the quick mask will be gone the next time you open your file.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 183
Classroom in a Book
1 With the (Standard mode) statue selection still active in the image window, click the
Save Selection As Channel button ( ) at the bottom of the Channels palette.
A new channel, Alpha 1, appears at the bottom of the Channels palette.
Using alpha channels
You may like to know these useful facts about alpha channels:
• An image can contain up to 56 channels, including all color and alpha channels.
• All channels are 8-bit grayscale images, capable of displaying 256 levels of gray.
• You can specify a name, color, mask option, and opacity for each channel. (The opacity affects the
preview of the channel, not the image.)
• All new channels have the same dimensions and number of pixels as the original image.
• You can edit the mask in an alpha channel using the painting tools, editing tools, and filters.
• You can convert alpha channels to spot-color channels.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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184 LESSON 6
Masks and Channels
2 Double-click the Alpha 1 channel, type Statue to rename it, and press Enter or Return.
When you select the channel, Photoshop displays a black-and-white representation of
the selection in the image window, and it hides all the color channels.
3 Choose Select > Deselect to deselect the statue.
4 Choose File > Save to save your work.
Masking tips and shortcuts
Here’s some useful information about masks and masking.
• Masks are nondestructive, which means that you can go back and reedit the masks later without
losing the pixels that they hide.
• When editing a mask, be aware of the color selected in the toolbox. Black hides, white reveals, and
shades of gray partially hide or reveal. The darker the gray, the more is hidden in the mask.
• To reveal a layer’s content without masking effects, turn off the mask by Shift-clicking the layer mask
thumbnail or choose Layer > Layer Mask > Disable. A red X appears over the mask thumbnail in the
Layers palette when the mask is disabled.
• To turn a layer mask back on, Shift-click the layer mask thumbnail with the red X in the Layers
palette or choose Layer > Layer Mask > Enable. If the mask doesn’t show up in the Layers palette,
choose Layer > Layer Mask > Reveal All to display it.
• Unlink layers and masks to move the two independently and shift the masks’ boundaries separately
from the layer. To unlink a layer or group to its layer mask or vector mask, click the link icon between
the thumbnails in the Layers palette. To relink them, click the blank space between the two thumbnails.
• To convert a vector mask to a layer mask, select the layer containing the vector mask you want to
convert, and choose Layer > Rasterize > Vector Mask. Note, however, that once you rasterize a vector
mask, you can’t change it back into a vector object.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 185
Classroom in a Book
Viewing channels
You’re ready to assemble a background for your book cover, using a mask to hide
unwanted elements. You’ll start by looking at each channel in the image, to determine
which channel offers the most contrast for the mask you’re about to create.
1 Drag the Layers palette by its tab to move it out of its stack and position the palette
next to the Channels palette. Expand both palettes, if necessary, so that you can see all of
their contents.
2 In the Layers palette, Alt-click (Windows) or Option-click (Mac OS) the eye icon ( )
next to the Background layer to hide all of the other layers. Select the Background layer.
3 Click the Channels palette tab to make the palette active, and then click the CMYK
channel to select it.
4 In the Channels palette, click the eye icon column next to the Cyan channel. You’ve
turned off the composite and Cyan channels, and are looking at the combination of the
Magenta, Yellow, and Black channels.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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186 LESSON 6
Masks and Channels
If you view a combination of channels, they appear in color, whether or not you are
viewing your channels in color.
Note: You can display channels in their respective colors (red, green, and blue; or cyan,
magenta, yellow, and black) by choosing Edit > Preferences > Interface (Windows) or
Photoshop > Preferences > Interface (Mac OS), and then selecting the Show Channels In
Color option. This can help you conceptualize how individual color channels contribute
to a composite image. However, because you’re working with the channel’s grayscale
information, to avoid distractions, leave the color view turned off.
5 Click next to the Magenta and Yellow channels to turn them off. Only the Black
channel remains visible. (You can’t turn off all channels in an image; at least one must
remain visible.)
Individual channels appear in grayscale. In grayscale, you can evaluate the tonal values
of the color components of the color channels, and decide which channel is the best
candidate for corrections.
6 In the Channels palette, click the Yellow channel name to turn off the Black channel
and turn on the Yellow channel, and then examine the contrast in the image. Repeat this
step for the Magenta and Cyan channels. What you’re looking for is the channel that
offers the easiest selection for the blue background.
Notice that in all channels but Cyan, the panels have a vertical dark streak. The Cyan
channel shows the panel background as solid black. The solid black offers the most
contrast, making the Cyan channel the easiest to select.
You’ll apply a levels adjustment to the channel, to make it easier to select.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
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ADOBE PHOTOSHOP CS3 187
Classroom in a Book
Adjusting individual channels
Now that you’ve identified the Cyan channel as the channel with the most contrast,
you’ll copy it and make adjustments to the copy.
1 Make sure that only the Cyan channel is visible in the Channels palette. Drag the
Cyan channel to the New Channel button ( ) at the bottom of the Channels palette to
make a copy. A channel named Cyan Copy appears in the Channels palette.
You’ll isolate the black panels with a levels adjustment.
2 Choose Image > Adjustments > Levels to display the Levels dialog box. Notice the
nearly flat part of the histogram: you’ll isolate these values.
3 Drag the black (shadows) slider to the right to the point where the black begins to
flatten out on the left side of the histogram; drag the white (highlights) slider to the left
to where the black values begin to flatten out on the right side of the histogram. (We used
values of 23, 1.00, and 45.) The preview shows the image as black and white. Click OK.
You’ll name the channel to keep track of your work.
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188 LESSON 6
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4 In the Channels palette, double-click the Cyan Copy name and rename it Panel Mask.
5 Choose File > Save to save your work so far.
Loading a mask as a selection
You will load the channel mask you just created as a selection, which you can then
convert to a layer mask. A layer mask lets you edit the layer relative to the selection.
1 In the Layers palette, click the eye icon ( ) next to the Garden layer to make it
visible, and then click the Garden layer name to select it.
2 Choose Select > Load Selection. For Channel, choose Panel Mask from the pop-up
menu. Select Invert to reverse the selection to mask the panels, not the background.
Click OK.
A selection marquee appears on the image.
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ADOBE PHOTOSHOP CS3 189
Classroom in a Book
3 With the selection active, at the bottom of the Layers palette, click the Add Layer
Mask button ( ) to mask the selection.
Notice that the Channels palette displays a new channel called Garden Mask. As long as
the Garden layer is selected, the Channels palette will display its mask.
4 In the Layers palette, click the Link icon ( ) between the image thumbnail and mask
thumbnail to unlink the two.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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190 LESSON 6
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5 Click the image thumbnail to make it active.
You want to be able to reposition the temple within the mask.
6 Select the Move tool ( ) in the toolbox. With the selection still active, drag to
reposition the image within the mask, so that the peak of the temple is visible in the
top panel.
7 When you are satisfied with how the image looks within the mask, in the Layers
palette click the area between the image thumbnail and layer mask thumbnail to relink
the two.
8 Save your work so far.
Loading a selection into an image using shortcuts
You can reuse a previously saved selection by loading it into an image. To load a saved selection using
shortcuts, do one of the following in the Channels palette:
• Select the alpha channel, click the Load Channel As Selection button at the bottom of the palette,
and then click the composite color channel near the top of the palette.
• Drag the channel that contains the selection you want to load onto the Load Channel As Selection
button.
• Ctrl-click (Windows) or Command-click (Mac OS) the channel containing the selection you want
to load.
• To add the mask to an existing selection, press Ctrl+Shift (Windows) or Command+Shift
(Mac OS), and click the channel.
• To subtract the mask from an existing selection, press Ctrl+Alt (Windows) or Command+Option
(Mac OS), and click the channel.
• To load the intersection of the saved selection and an existing selection, press Ctrl+Alt+Shift
(Windows) or Command+Option+Shift (Mac OS), and select the channel.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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ADOBE PHOTOSHOP CS3 191
Classroom in a Book
Applying filters to a mask
Next, you will refine the selection of the panels by applying a filter. You worked in
CMYK mode to isolate the Cyan channel. Now you’ll convert the image to RGB mode
to apply an RGB filter from the Filter Gallery. A limited number of filters are available in
CMYK mode; Filter Gallery filters work only on RGB images.
1 In the Channels palette, make sure that the CMYK composite channel is selected.
2 Choose Image > Mode > RGB. At the alert, click Don’t Flatten. The image is
converted to RGB. If a compatibility alert appears, click OK.
3 Choose Filter > Filter Gallery to display the Filter Gallery dialog box.
4 In the Gallery, click the arrow to the left of the Distort folder to display its filters.
Then click Glass. Set the Distortion to 2 and Smoothness to 4 to make it look like glass
on a rainy day. Click OK.
Applying effects using a gradient mask
Now you’ll create a gradient mask and use it to apply a filter that fades into the image.
In addition to using black to indicate what’s hidden and white to indicate what’s
selected, you can paint with shades of gray to indicate partial transparency. For example,
if you paint in a mask with a shade of gray that is at least halfway between white and
black, the underlying image becomes partially (50% or more) visible.
1 In the Layers palette, click the eye icon ( ) to the left of the Writing layer to display
the layer with an image of bronze lettering. Click the layer name to select the layer.
2 At the bottom of the Layers palette, click the Add Layer Mask button ( ) to add a
layer mask to the Writing layer.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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192 LESSON 6
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3 Click the Writing layer mask thumbnail to select it. A black border appears around
the layer mask, indicating that it, not the image, is selected. You want to apply an effect
to the mask, not the image.
4 Click the Gradient tool ( ) in the toolbox to select it. In the tool options bar at the
top, make sure that the default gradient linear, and White to Black, is selected.
5 In the image window, hold down the Shift key and drag the gradient straight across
from the center left side of the image to the right, where the wall meets the window.
Notice that the layer mask thumbnail now displays the gradient.
This gradient will gradually reveal (where the mask is white) the filter you’re about
to add to the Writing image, and gradually hide the effect (where the mask is black).
Gradient pixel values that decrease from 255 (black) to 0 (white) gradually reveal more
of what’s under the mask.
Now you will add a filter to the mask.
6 Make sure that the black border still appears around the layer mask, indicating that
it, not the layer thumbnail, is selected.
Chapter 6. Masks and Channels
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ADOBE PHOTOSHOP CS3 193
Classroom in a Book
7 Choose Filter > Filter Gallery. If necessary, click the left arrow button to the left of
the Texture folder to expands its contents. Click Mosaic Tiles and adjust its settings.
(We used Tile Size, 18; Grout Width, 4; and Lighten Grout, 1.) Click OK.
8 Choose File > Save to save your work.
Resizing the canvas
Next, you’ll add canvas area to the image so that you can create a background for the
cover title and byline.
1 Make sure that the background color is set to white in the toolbox. (To set it quickly,
click the Default Colors button in the toolbox, and then press X to switch the colors so
that the background is white.)
2 Choose Image > Canvas Size. In the Canvas Size dialog box, select Relative to add to
the existing image size. Enter a Height of 2 inches. In the Anchor area, click the lower
center square to add canvas centered at that spot. Click OK.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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194 LESSON 6
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You’ll perform Step 2 again to add canvas to the bottom of the image.
3 Choose Image > Canvas Size. In the Canvas Size dialog box, make sure that Relative
is still selected, change the Height to 1 inch, and in the Anchor area, click the upper
center square. Click OK.
Extracting the paper texture
You’ll add a torn-paper background to the canvas you just created. The paper was
scanned against a white background. One way to mask a delicate edge is using the
Extract feature.
The Extract command provides a sophisticated way to isolate a foreground object from
its background. Even objects with wispy, intricate, or undefinable edges can be clipped
from their backgrounds with a minimum of effort.
1 Click the Go To Bridge button ( ) in the tool options bar to jump to Adobe Bridge,
locate the 06Paper.psd image file in the Lessons/Lesson06 folder, and double-click its
thumbnail preview to open it in Photoshop.
You’ll start with an image that consists of only one layer. You must be working in a
layer to use the Extract command. In this case, because the image has no layers—that
is, it has only a background—the Extract filter will replace the Background layer with
a new layer.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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ADOBE PHOTOSHOP CS3 195
Classroom in a Book
Note: The paper image has the same resolution as the Start file, 72 ppi. To avoid
unexpected results when combining elements from multiple files, you must either use files
with the same image resolution, or compensate for differing resolutions. For example,
if your original image is 72 ppi and you add an element from a 144-ppi image, the
additional element will appear twice as large. For information on resolutions, see “Pixel
dimensions and image resolution” in Photoshop Help.
2 Choose Filter > Extract. The Extract dialog box appears with the Edge Highlighter
tool ( ) selected in the upper left area of the dialog box.
The Extract dialog box lets you highlight the edges of the object, define the object’s
interior, and preview the extraction. You can refine and preview the extraction as many
times as you wish.
If needed, you can resize the dialog box by dragging its bottom right corner.
3 On the right side of the dialog box, locate the Brush Size option, and then type or
drag the slider to 97 pixels.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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196 LESSON 6
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4 Using the Edge Highlighter tool, brush along the white edge around the entire piece
of paper, slightly overlapping the highlighter over the paper edge. The green outline
should form a closed shape around the entire piece of paper.
If you make a mistake and highlight more than desired, select the Eraser tool ( ) in the
dialog box and drag over the highlight in the preview.
5 Select the Fill tool ( ), under the Edge Highlighter tool, and click inside the outlined
foxtail tip to fill its interior. (You must define the object’s interior before you can preview
the extraction.)
The default fill color (bright blue) contrasts well with the edge highlight color (green).
You can change either color if you need more contrast with the image colors using the
Highlight and Fill pop-up menus in the Extract dialog box.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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ADOBE PHOTOSHOP CS3 197
Classroom in a Book
6 Click OK to apply the extraction. Layer 0 appears in the Layers palette, replacing the
Background layer.
The image window displays the extracted area against the checkerboard pattern that
indicates transparency.
Once you’ve extracted an image, you can also use the Background Eraser and History
Brush tools to clean up any stray edges in the image.
7 Choose File > Save to save your work so far.
An alternative method for making intricate selections is to select areas by color. To
do so, choose Select > Color Range. Then, use the eyedropper tools from the Color Range
dialog box to sample the colors for your selection. You can sample from your image
window or from the preview window.
Refining a selection in the Extract dialog box
To refine your selection, edit the extraction boundaries using these techniques:
• Switch between the Original and Extracted views using the Show menu.
• Click a filled area with the Fill tool to remove the fill.
• Select the Eraser tool (
) and drag to remove any undesired highlighting.
• Select the Show Highlight and Show Fill options to view the highlight and fill colors; deselect the
options to hide them.
• Zoom in on your selection using the Zoom tool. Then, use a smaller brush size as you edit,
switching between the Edge Highlighter tool and the Eraser tool as needed for more precise work.
• Toggle quickly between the Edge Highlighter and Eraser tools when one of them is selected by
pressing B (Edge Highlighter) or E (Eraser).
• Switch to a smaller brush by entering a different size in the Brush Size option, and continue to refine
the selection border using the Edge Highlighter tool or to erase using the Eraser tool.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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Moving layers between documents
Often, you may need to move layers from one Photoshop document to another. It’s very
easy to do. Here, you’ll move the paper texture you just extracted to the book cover
composition, to add a background texture.
1 With both the your 06Working and Paper images visible on-screen, make sure that
the Paper image is active.
2 Drag Layer 0 from the Paper image’s Layers palette, into the center of your
06Working image. The layer is added as Layer 1, just below the top layer, Buddha.
3 In the Layers palette, select the layer name and rename it Paper.
Dragging the Paper image layer into the 06Working image adds the layer to its Layers palette.
4 Choose View > Rulers. Drag a ruler guide down from the top of the document to 2¼.”
5 Select the Move tool ( ) in the toolbox. Move the paper to center it along the top of
the book cover, so that the paper’s bottom edge aligns with the 2¼” guide.
Chapter 6. Masks and Channels
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ADOBE PHOTOSHOP CS3 199
Classroom in a Book
Colorizing with an adjustment layer
Now you’ll create an adjustment layer to colorize the paper.
1 In the Layers palette, make sure that the Paper layer is selected.
2 At the bottom of the Layers palette, click the Create New Fill Or Adjustment Layer
button ( ) to create an adjustment layer. Choose Hue/Saturation from the pop-up
menu.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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3 In the Hue/Saturation dialog box, enter these values to give the paper a violet cast:
Hue: –125, Saturation –56, Lightness –18). Click OK.
The entire image takes on a purplish cast. You can confine the effect to just the paper by
creating a clipping layer.
4 Hold down the Alt (Windows) or Option (Mac OS) key, and position the pointer
between the Hue/Saturation adjustment layer and the Paper layer to display a doublecircle icon ( ). Then click to create a clipping layer.
In the Layers palette, the Hue/Saturation layer indents and displays an arrow pointing to
the layer beneath it, Paper, which is now underlined. This shows that the Paper layer is
now clipped to the adjustment layer, meaning that the effect applies only to that layer.
5 Choose File > Save to save your work so far.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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ADOBE PHOTOSHOP CS3 201
Classroom in a Book
Grouping and clipping layers
You’ll complete the composition by rearranging some layers and adding text.
1 In the Layers palette, turn on and select the Buddha layer. Make sure that it is at the
top of the Layers palette.
2 In the Layers palette, select the Paper layer and the Hue/Saturation adjustment layer.
Click the icon ( ) in the upper right of the Layers palette to display the Layers palette
menu, and choose New Group From Layers. Name this group Top Paper. Click OK.
Now you’ll duplicate this layer group for the bottom part of the book cover.
3 Using the Layers palette menu, choose Duplicate Group.
4 In the Duplicate Group dialog box, for Duplicate As, type Bottom Paper. Click OK.
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5 In the Layers palette, click the triangle next to the Bottom Paper and Top Paper
layers to view their contents. As you can see, the Bottom Paper layer now has the same
contents as the Top Paper layer, duplicated in the same location in the image. Click the
triangles again to collapse the layer contents.
6 In the Layers palette, click the eye icon next to the Top Paper layer group to hide the
layer group.
7 With the Bottom Paper layer selected in the Layers palette, choose Edit >
Transform > Rotate 180º.
8 Use the Move tool ( ) to drag the rotated paper to the bottom of the composition,
so that the top of the lower edge is at about 6½” on the ruler.
9 In the Layers palette, click in the Show/Hide Visibility column next to the Top Paper
layer group to redisplay the layer group.
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Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
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ADOBE PHOTOSHOP CS3 203
Classroom in a Book
10 Choose View > Rulers to hide the rulers.
Applying a mask from a saved selection
Remember the beautiful mask that you created at the start of this lesson? Now it’s time
to retrieve it to mask out the background.
1 Select the Buddha layer at the top of the Layers palette.
2 Choose Select > Load Selection. For Channel, choose Statue. Select Invert to reverse
the selection, and click OK.
3 At the bottom of the Layers palette, click the Add Layer Mask button ( ) to mask
the selection and hide the statue’s background.
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204 LESSON 6
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You can see how helpful it is to have the flexibility to apply saved alpha channels at
various stages of your workflow.
Remember that you can adjust the image within the mask: In this case, you’ll move the
mask and the masked image together.
5 In the Layers palette with the Buddha layer selected, click its layer mask thumbnail to
select the mask. In the Channels palette, notice that the Statue channel is selected. In the
Document window, use the Move tool to adjust the masked image so that both the top
halo and base of the statute extend about ½-inch into the paper.
Now you’ll adjust how the statue appears on the paper.
6 In the Layers palette, select the Bottom Paper layer group and move it by dragging it
above the Buddha layer. You want the paper to cover the base of the Buddha statue.
7 Choose File > Save to save your work.
Using type as a mask
Just as you can mask with selections, you can mask with type. Now you’ll reveal the
original paper texture, using type to mask the colorized paper.
1 Select the Type tool ( ) in the toolbox. In the options bar, set the font to Minion Pro
Regular, Center alignment, and 75 pt in size. Set black as the text color.
Chapter 6. Masks and Channels
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ADOBE PHOTOSHOP CS3 205
Classroom in a Book
2 Click with the Type tool in the center of the top paper background, and type
Zen Garden.
To add the paper texture, first you will copy it.
3 In the Layers palette, click the arrow next to the Top Paper layer group to expand its
contents.
4 Press the Alt (Windows) or Option (Mac OS) key, and drag the Paper layer to just
above the Zen Garden type layer. This makes a copy of the Paper layer on top of the
type layer.
You must move the layer out of its layer group to be able to create a clipping group
in the next step. You can clip two layers together, but you cannot clip together a layer
group and a layer.
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206 LESSON 6
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5 To clip the Paper Copy layer to the Zen Garden type layer, position the pointer
between the two layers, and hold down Alt (Windows) or Option (Mac OS) to display
the double-circle clipping layer icon ( ); Click when this icon appears.
The original gold paper texture shows through the type. Now you’ll make the type pop a
bit more with a drop shadow.
6 To add a drop shadow, select the Zen Garden type layer. Click the Add Layer Style
button ( ) at the bottom of the Layers palette, and choose Drop Shadow from the
pop-up menu. In the Layer Style dialog box under the Drop Shadow options, select the
Multiply blending mode; set the Distance to 12, Spread to 5, Size to 29. Click OK.
Note: If you make a mistake and inadvertently add the Drop Shadow effect to the Paper
Copy layer, simply drag the effect to the Zen Garden type layer to apply it there.
To complete the composition and this lesson, you’ll add your name as the author to the
bottom paper texture.
7 In the Layers palette, make sure that the top layer is selected, so that the new type
layer will be created above it.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
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Chapter 6. Masks and Channels
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ADOBE PHOTOSHOP CS3 207
Classroom in a Book
8 To color the type, select the Eyedropper tool ( ) in the toolbox. Click a light green
color from the shrubbery in the panel area to sample the color.
9 Select the Type tool ( ) in the toolbox. In the Type tool options bar, choose Minion
Pro Regular for the font, and 15 pt for the size.
10 Position the Type tool over the center of the bottom paper texture. Type the author
name [your name here].
11 Press Ctrl (Windows) or Command (Mac OS) to get the Move tool, and drag to
position the type in the center of the bottom paper.
Your book cover is complete.
12 Choose File > Save.
You have completed this lesson. Although it takes some practice to become comfortable
using channels, you’ve learned all the fundamental concepts and skills you need to get
started using masks and channels.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
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208 LESSON 6
Masks and Channels
About masks and masking
Alpha channels, channel masks, clipping masks, layer masks, vector masks—what’s the difference? In
some cases, they’re interchangeable: a channel mask can be converted to a layer mask, a layer mask can
be converted to a vector mask and vice versa.
Here’s a brief description to help you keep them all straight. What they have in common is that all store
selections, and all let you edit an image nondestructively and return at any time to your original.
• An alpha channel—also called a mask or selection—is an extra channel added to an image that
stores selections as grayscale images. You can add alpha channels to create and store masks.
• A layer mask is like an alpha channel, just attached to a specific layer. A layer mask lets you control
which part of a layer is revealed or hidden. A layer mask appears as a blank thumbnail next to the layer
thumbnail in the Layers palette; a black outline indicates that its selected.
• A vector mask is essentially a layer mask made up of vectors, not pixels. Resolution independent,
vector masks have crisp edges and are created with the pen or shape tools. They do not support
transparency and so their edges cannot be feathered. Their thumbnail appears the same as layer mask
thumbnails.
• A clipping mask applies to a layer. It lets you confine the influence of an effect to specific layers,
rather than to everything below the layer in the layer stack. Using a clipping mask clips layers to a base
layer: only that base layer is affected. Thumbnails of a clipped layer are indented with a right-angle
arrow pointing to the layer below. The clipped base layer is underlined.
• A channel mask restricts editing to a specific channel (for example, a Cyan channel in a CMYK
image). Channel masks are useful for making intricate, fringed, or wispy-edged selections. You can
create a channel mask based on a dominant color in an image or pronounced contrast in an isolated
channel, for example, between the subject and the background. An alternative to using a channel mask
is the Extract command, which lets you cut out complex subjects from their backgrounds.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Chapter 6. Masks and Channels
Page 38
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Review
Review questions
1 What is the benefit of using a quick mask?
2 What happens to a quick mask when you deselect it?
3 When you save a selection as a mask, where is the mask stored?
4 How can you edit a mask in a channel once you’ve saved it?
5 How do channels differ from layers?
6 How do you use the Extract command to isolate an object with intricate
borders from an image?
Review answers
1 Quick masks are helpful for creating quick, onetime selections. In addition,
using a quick mask is an easy way to edit a selection using the painting tools.
2 The quick mask disappears when you deselect it.
3 Masks are saved in channels, which can be thought of as storage areas for color
and selection information in an image.
4 You can paint on a mask in a channel using black, white, and shades of gray.
5 Channels are used as storage areas for saved selections. Unless you explicitly
display a channel, it does not appear in the image or print. Layers can be used to
isolate various parts of an image so that they can be edited as discrete objects with
the painting or editing tools or other effects.
6 You use the Extract command to extract an object, and the Extract dialog
box to highlight the edges of the object. Then, you define the object’s interior
and preview the extraction. Applying the extraction erases the background
to transparency, leaving just the extracted object. You can also use the Force
Foreground option to extract a monochromatic or uniform-colored object based
on its predominant color.
Chapter 6. Masks and Channels
Adobe® Photoshop® CS3 Classroom in a Book® By Adobe Creative Team ISBN:
Prepared for Hal Peterson, Safari ID: hal@halpeterson.com
9780321492029 Publisher: Adobe Press
Print Publication Date: 2007/04/16
User number: 1002568
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use
requires prior written consent from the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.