Using Help
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153
Adobe Photoshop Help
Making Color and Tonal Adjustments
Using Help
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Contents
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Index
Back
153
Using the Desaturate command
The Desaturate command converts a color image to a grayscale image in the same color
mode. For example, it assigns equal red, green, and blue values to each pixel in an RGB
image to make it appear grayscale. The lightness value of each pixel does not change.
This command has the same effect as setting Saturation to –100 in the Hue/Saturation
dialog box.
Note:
If you are working with a multilayer image, Desaturate converts the selected layer
only.
To use the Desaturate command:
Choose Image > Adjustments > Desaturate.
Using the Invert command
The Invert command inverts the colors in an image. You might use this command to make
a positive black-and-white image negative or to make a positive from a scanned black-
and-white negative.
Note:
Because color print film contains an orange mask in its base, the Invert command
cannot make accurate positive images from scanned color negatives. Be sure to use the
proper settings for color negatives when scanning film on slide scanners.
When you invert an image, the brightness value of each pixel in the channels is converted
to the inverse value on the 256-step color-values scale. For example, a pixel in a positive
image with a value of 255 is changed to 0, and a pixel with a value of 5 to 250.
To use the Invert command:
Choose Image > Adjustments > Invert, or choose Layer > New Adjustment Layer > Invert
(Photoshop).
Using the Equalize command (Photoshop)
The Equalize command redistributes the brightness values of the pixels in an image so
that they more evenly represent the entire range of brightness levels. When you apply this
command, Photoshop finds the brightest and darkest values in the composite image and
remaps them so that the brightest value represents white and the darkest value repre-
sents black. Photoshop then attempts to equalize the brightness—that is, to distribute the
intermediate pixel values evenly throughout the grayscale.
You might use the Equalize command when a scanned image appears darker than the
original and you want to balance the values to produce a lighter image. Using Equalize
together with the Histogram command lets you see before-and-after brightness
comparisons.
To use the Equalize command:
1
Choose Image > Adjustments > Equalize.
2
If you selected an area of the image, select what to equalize in the dialog box, and
click OK:
•
Equalize Selected Area Only to evenly distribute only the selection’s pixels.
•
Equalize Entire Image Based on Selected Area to evenly distribute all image pixels
based on those in the selection.
