Saving And Managing Channels - Adobe PHOTOSHOP 5.0 User Manual

To delete a channel with confirmation:
Select the channel in the Channels palette.
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Click the Trash button at the bottom of the
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palette. Then click Yes.
When deleting a channel from a file with layers,
regardless of the method you use, Photoshop
prompts you first to flatten the visible layers and
discard hidden layers (if any) before deleting the
channel. This is necessary because removing a
color channel converts the image to Multichannel
mode, which does not support layers.
Mixing channels
The Channel Mixer command lets you modify a
color channel using a mix of the current color
channels. With this command, you can do the
following:
Make creative color adjustments not easily done
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with the other color adjustment tools.
Create high-quality grayscale images by
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choosing the percentage contribution from each
color channel.
Create high-quality sepia-tone or other tinted
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images.
Convert images to and from some alternative
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color spaces, such as YCrCb.
Swap or duplicate channels.
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For a color illustration of the Channel
Mixer, see figure 10-3 on page 227.
To mix channels in an image:
1 In the Channels palette, select the composite
channel.
2 Choose Image > Adjust > Channel Mixer.
For Output Channel, choose the channel in
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which to blend one or more existing (or source)
channels.
Drag any source channel's slider to the left to
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decrease the channel's contribution to the output
channel, to the right to increase it, or enter a value
between –200% and +200% in the text box. Using
a negative value inverts the source channel before
adding it to the output channel.
5 If desired, drag the slider or enter a value for the
Constant option. This option adds a channel of
varying opacity to the output channel: negative
values act as a black channel, positive values act as
a white channel.
If desired, select Monochrome to apply the same
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settings to all the output channels, creating a color
image that contains only gray values.
Selecting Monochrome is useful for images you
plan to convert to grayscale. If you select and then
deselect this option, you can modify the blend of
each channel separately, creating a handtinted
appearance.

Saving and managing channels

As long as you save a file in a format supporting the
image's color mode, the color channels will be
preserved. But alpha channels are automatically
kept only when you save a file in the Adobe
Photoshop, Adobe Photoshop 2.0 (Mac OS only),
DCS 2.0, PICT, TIFF, or Raw formats. Saving in
other formats may cause channel information to
be discarded (see "About file formats" on
page 321).
ADOBE PHOTOSHOP 5.0 243
User Guide