Справочник Пользователя для Adobe photoshop cs2
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Chapter 15: Using channels and spot
colors
colors
Channels
About channels
Channels are grayscale images that store different types of information:
•
Color information channels are created automatically when you open a new image. The image’s color mode deter
mines the number of color channels created. For example, an RGB image has a channel for each color (red, green,
and blue) plus a composite channel used for editing the image.
mines the number of color channels created. For example, an RGB image has a channel for each color (red, green,
and blue) plus a composite channel used for editing the image.
•
Alpha channels store selections as grayscale images. You can add alpha channels to create and store masks, which
let you manipulate or protect parts of an image.
let you manipulate or protect parts of an image.
•
Spot color channels specify additional plates for printing with spot color inks.
An image can have up to 56 channels. The file size required for a channel depends on the pixel information in the
channel. Certain file formats, including TIFF and Photoshop formats, compress channel information and can save
space. The size of an uncompressed file, including alpha channels and layers, appears as the rightmost value in the
status bar at the bottom of the window when you choose Document Sizes from the pop-up menu.
channel. Certain file formats, including TIFF and Photoshop formats, compress channel information and can save
space. The size of an uncompressed file, including alpha channels and layers, appears as the rightmost value in the
status bar at the bottom of the window when you choose Document Sizes from the pop-up menu.
Note: As long as you save a file in a format supporting the image’s color mode, the color channels are preserved. Alpha
channels are preserved only when you save a file in Photoshop, PDF, PICT, Pixar, TIFF, or raw formats. DCS 2.0 format
preserves only spot channels. Saving in other formats may cause channel information to be discarded.
channels are preserved only when you save a file in Photoshop, PDF, PICT, Pixar, TIFF, or raw formats. DCS 2.0 format
preserves only spot channels. Saving in other formats may cause channel information to be discarded.
See also
Channels in ImageReady
In ImageReady, you can work with alpha channels created in Photoshop by loading selections from alpha channels
saved in the image. You can also save selections as alpha channels in ImageReady, load those alpha channels as selec
tions, and delete alpha channels. ImageReady commands for working with alpha channels are under the Select menu.
You can’t view individual color channels and alpha channels, or create spot color channels in ImageReady. If you need
to do more complex channel operations, edit the image in Photoshop.
saved in the image. You can also save selections as alpha channels in ImageReady, load those alpha channels as selec
tions, and delete alpha channels. ImageReady commands for working with alpha channels are under the Select menu.
You can’t view individual color channels and alpha channels, or create spot color channels in ImageReady. If you need
to do more complex channel operations, edit the image in Photoshop.
About the Channels palette
The Channels palette lets you create and manage channels. The palette lists all channels in the image—composite
channel first (for RGB, CMYK, and Lab images). A thumbnail of the channel’s contents appears to the left of the
channel name; the thumbnail is automatically updated as you edit the channel.
channel first (for RGB, CMYK, and Lab images). A thumbnail of the channel’s contents appears to the left of the
channel name; the thumbnail is automatically updated as you edit the channel.