Correcting colors in cmyk and rgb, Identify out-of-gamut colors, Find out-of-gamut colors – Adobe Photoshop CS4 User Manual
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USING PHOTOSHOP CS4
Color and tonal adjustments
Last updated 1/10/2010
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In an adjustment dialog box, click Load. Locate and load the saved adjustment file. In the Curves, Black & White,
Exposure, Hue/Saturation, Selective Color, Levels, or Channel Mixer dialog boxes, saved presets appear in the
Presets menu. Choose Load Preset from the Preset option to load a preset not shown on the Preset pop-up menu
from a different location.
To remove default presets, navigate to the following folders, move the presets out of the folders, and restart Photoshop.
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Windows: [startup drive]/Program Files/Adobe/Adobe Photoshop CS4/Presets/[adjustment type]/[preset name]
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Mac OS: [startup drive]/Applications/Adobe Photoshop CS4/Presets/[adjustment type]/[preset name]
Correcting Colors in CMYK and RGB
Although you can perform all color and tonal corrections in RGB mode and most adjustments in CMYK mode, choose
a mode carefully. Avoid multiple conversions between modes, because color values are rounded and lost with each
conversion. Don’t convert RGB images to CMYK mode if they are meant for on-screen display. For CMYK images
that are separated and printed, do not make color corrections in RGB mode.
If you must convert your image from one mode to another, perform most of your tonal and color corrections in RGB
mode. You can then use CMYK mode for fine-tuning. The advantages of working in RGB mode are:
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RGB has fewer channels. As a result, your computer uses less memory.
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RGB has a wider range of colors than CMYK, and more colors are likely to be preserved after adjustments.
You can soft proof colors to see an on-screen preview of how your document’s colors will look when reproduced
on a particular output device. See “
You can edit an image in RGB mode in one window and view the same image in CMYK colors in another window.
Choose Window
> Arrange
> New Window For (Filename) to open a second window. Select the Working CMYK
option for Proof Setup, then choose the Proof Color command to turn on the CMYK preview in one of the windows.
Identify out-of-gamut colors
A gamut is the range of colors that a color system can display or print. A color that can be displayed in RGB could be
out of gamut, and therefore unprintable, for your CMYK setting.
In RGB mode, you can tell whether a color is out of gamut in the following ways:
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In the Info panel, an exclamation point appears next to the CMYK values whenever you move the pointer over an
out-of-gamut color.
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In both the Color Picker and the Color panel, an alert triangle
appears. When you select an out-of-gamut color,
the closest CMYK equivalent is displayed. To select the CMYK equivalent, click the triangle or the color patch.
Photoshop automatically brings all colors into gamut when you convert an RGB image to CMYK. Note that some
detail in the image may be lost, depending on your conversion options. You can identify the out-of-gamut colors
in an image or correct them manually before converting to CMYK. You can use the Gamut Warning command to
highlight out-of-gamut colors.
Find out-of-gamut colors
1
Choose View
> Proof Setup, then choose the proof profile on which you want to base the gamut warning.
2
Choose View
> Gamut Warning.
All pixels outside the gamut of the current proof profile space are highlighted in gray.