Adobe Photoshop CS2 On Demand [Electronic resources] نسخه متنی

Using Channels to Create and Store Selections

Photoshop's primary method of creating selections is through the use of tools on the toolbox, such as the Marquee, Lasso, and Magic Wand, and while they create impressive and complex selections, Photoshop has other ways to capture that tricky selection using the Channels palette. The Channels palette primarily holds color information, but that's not all it can hold. You can use the Channels palette to create and store complex selections. Photoshop holds selection information using black (mask), white (selection), and shades of gray (percentages of selection). In addition, channels are saved with the image file.

Create Selections with Channels

Select the

Channels palette.

Click the individual color channels.

Look for a channel that represents a brightness difference between what you want to select and what you want to mask.

Make a copy of the channel by dragging it down over the New Channel button on the Channels palette.

Select the new channel.

Click the

Image menu, point to

Adjustments , and then

Threshold .

Drag the

Threshold slider left or right until the visible image represents a black and white mask of your selection.

Click

OK .

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Apply Selection Masks to an Image

Click the

Select menu, and then click

Load Selection .

Click the

Channel list arrow, and then select the newly created channel.

Click

OK .

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