© 2011 Delmar, Cengage Learning Chapter 10 Enhancing Specific Selections.

© 2011 Delmar, Cengage Learning

Chapter 10

Enhancing Specific Selections

Chapter Lessons• Create an alpha channel• Isolate an object• Erase areas in an image to enhance

appearance• Use the Clone Stamp tool to make repairs• Use the Magic Wand tool to select objects• Learn how to create snapshots• Create multiple-image layouts

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• Nearly every image opened or created in Photoshop is separated into channels

• Channels are used to house the color information for each layer and layer mask in an image

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Using Channels

• Isolate areas

• Erase areas using a variety of eraser tools

• Take a sample and then paint that sample over an area using the Clone Stamp tool

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Fixing Imperfections

• Use the snapshot command to make a temporary copy of any state of an image

• The snapshot is added (above the states) at the top of the History panel

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Creating Snapshots

• Name a snapshot to make it easy to identify and manage

• Compare changes to images easily: take a snapshot before and after making changes

• Recover work easily

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Advantages of Snapshots

• Create an image that contains various sizes of the same image or several different images

• Print images in a variety of sizes and shapes on a single sheet

• Create a contact sheet consisting of thumbnail images

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Using Automation Features

• Created automatically in a new image

• Used to store color information about images

• Example:– A CMYK image has at least four

channels (cyan, magenta, yellow, black)

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Create an Alpha Channel

• An image can consist of from 1 to 24 color channels

• Default channels are color channels contained in an image and created automatically

• Add Alpha or Spot channels to images displayed in all color modes, except the bitmap modes

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More on Channels

• Alpha Channels and Spot Channels specify color information added to the image

• Alpha channel is used to:– Create and store masks to manipulate,

isolate, or protect parts of an image

• Spot channel contains:– Information about special pre-mixed inks

used in CYMK color printing

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Alpha and Spot Channels

• Created on the Channels panel• Can create an alpha channel that

masks all or specific areas of a layer• Use alpha channels to:

– Preserve a selection for experimentation– Use later– Create special effects – Save and reuse in other images

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Understanding Alpha Channels

• Use the following formats to save an alpha channel:– PSD– PDF– PICT– TIFF– Raw

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Alpha channels do not print

Saving an Alpha Channel

• Lists all the default channels contained in a layer

• Manages all the image’s channels

• To access:– Click the Channels tab next to the

Layers tab

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Understanding the Channels Panel

• On the Channels panel, channels appear in the following order:– Composite channel: combination of

other default channels– Additional default channels that are

based on existing color modes– Spot color channels– Alpha channels

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Order of Channels

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Channels Panel

• Hide channels

• Re-order channels

• View channels as thumbnails on the Channels panel

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Channel Properties

• Select a portion of an image• Click the Save selection as channel

button on the Channels panel• Double-click the Alpha 1 thumbnail

on the Channels panel• Click the color box in the Channel

Options dialog box• Set the color and select options

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Creating an Alpha Channel

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Before

After

Red alpha channel overlaying purple produced violet

Alpha Layer Example

• Use the Extract plug-in to isolate a foreground object from its background

• After extracting an image, modify the extracted object layer as required

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Isolating an Object

• Use tools in the Extract dialog box to extract objects:– Use the Edge Highlighter tool to

trace the edge of the object to extract– Use the Fill tool to select everything

inside the edge

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Using Extract

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Extra Plug-in Tools

• Use eraser tools to erase an area without going through the extraction process

• Three eraser tools are available:– Eraser tool– Background Eraser tool– Magic Eraser tool

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Using Erase Tools

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Magic Eraser erases similarly colored pixels

Background Eraser exposes transparency

of the layer below

Eraser tool exposes

background color

Eraser Tool Examples

• Use the Clone Stamp tool to copy a sample in an image, then paste it over an area to cover

• Size of the sample taken depends on the brush tip size selected

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Fix Imperfections in an Image

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Object to delete

Sampled area applied to hide portions of the

object

Using the Clone Stamp Tool

• Use the Magic Wand tool to choose pixels that are similar to pixels clicked in an image

• Specify tolerance settings

• Specify whether to select only contiguous pixels

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Using the Magic Wand Tool

• Tolerance setting determines the range of colors that can be selected with the Magic Wand tool

• Example:– Low tolerance: Magic Wand tool

selects a narrow range of pixels– High tolerance: Magic Wand tool

selects a wider range of pixels

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Understanding Tolerance

• Area selected by the Magic Wand tool is related to the settings for the Eyedropper tool

• While working with the Magic Wand tool, verify or change Eyedropper tool settings as needed

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Using the Eyedropper Tool

• Create a snapshot of the image at various stages:– Before beginning an editing session– After crucial changes have been made

• Use the snapshot to revert to original image settings, if required

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Creating Snapshots

• Click the Create new snapshot button on the History panel

• Each new snapshot is numbered consecutively, and can be renamed

• Snapshots appear in order at the top of the History panel

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Creating Snapshots

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Creating Snapshots

• Created in Adobe Bridge

• Generate multiple-image layouts

• A picture package can contain multiple sizes of a single image

• Can be saved as a PDF

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Create Multiple-Image Layouts

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Sample Picture Package

• Assemble a maximum of 30 thumbnail images per page within a folder

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Assembling a Contact Sheet