Special-Purpose Color Adjustment Commands - Adobe PHOTOSHOP 5.0 User Manual

130 CHAPTER 6
Making Color and Tonal Adjustments
To subtract a color, click its opposite on the color
•
wheel (see "Adjusting color balance" on page 123).
For example, to subtract cyan, click red.
4 Click the thumbnails on the right of the dialog
box to adjust the brightness in the image.
Each time you click a thumbnail, all thumbnails
change. The center thumbnail always reflects the
current choices.
Using the Brightness/Contrast command
Using the Brightness/Contrast command is the
easiest way to make simple adjustments to the
tonal range of the image. Unlike Curves and
Levels, this command adjusts all pixel values in the
image at once—highlights, shadows, and
midtones. In addition, the Brightness/Contrast
command does not work with individual channels
and is not recommended for high-end output.
To use the Brightness/Contrast dialog box:
Open the Brightness/Contrast dialog box, as
1
described in "Using color adjustment commands"
on page 105.
Drag the sliders to adjust the brightness and
2
contrast.
Dragging to the left decreases the level and to the
right increases it. The number at the right of each
slider value displays the brightness or contrast
value. Values can range from –100 to +100.
3 When you've finished making adjustments,
click OK.
Special-purpose color
adjustment commands
The Invert, Equalize, Threshold, Posterize, and
Desaturate commands also change colors or
brightness values in an image but are typically
used for enhancing color and producing special
effects, rather than for correcting color.
Note: You can also make color adjustments with the
Channel Mixer command. (See "Mixing channels"
on page 243.)
Using the Invert command
The Invert command inverts 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 film contains an orange mask in
its base, the Invert command cannot make negatives
and positives from scanned color film.
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.