Set curve display options, Adjust color and tonality with curves – Adobe Photoshop CS4 User Manual
Page 176
169
USING PHOTOSHOP CS4
Color and tonal adjustments
Last updated 1/10/2010
Set Curve display options
You can control the curve grid display using the Curve display options.
1
Do one of the following:
•
Click the Curves icon
or a Curves preset in the Adjustments panel, or choose Curves from the panel menu.
•
Choose Layer
> New Adjustment Layer
> Curves. Click OK in the New Layer dialog box.
•
Choose Image > Adjustments
> Curves.
Note: Choosing Image
> Adjustments
> Curves applies the adjustment directly to the image layer and discards image
information.
2
In the Adjustments panel, choose Curve Display Options from the panel menu.
Note: If you chose Image > Adjustments > Curves, expand the Curve Display Options in the Curves dialog box.
3
Choose any of the following:
•
To reverse the display of intensity values and percentages, choose Show Amount Of Light (0-255) or Show Amount
Of Pigment/Ink
%. Curves displays the intensity values for RGB images in a range from 0 to 255, with black (0) at
the lower-left corner. Percentages for CMYK images are displayed in a range from 0 to 100, with highlights (0%) at
the lower-left corner. After the intensity values and percentages are reversed, 0 is at the lower-right corner for RGB
images; 0% is at the lower-right corner for CMYK images.
•
To display gridlines in 25% increments, select Simple Grid; to display in 10% increments, choose Detailed Grid.
To change the gridline increment, Alt-click (Windows) or Option-click (Mac OS) the grid.
•
To display color channel curves superimposed on the composite curve, choose Show Channel Overlays.
•
To display a histogram overlay, choose Show Histogram. For more information on how to read a histogram, see
“
•
To display a baseline drawn on the grid at a 45-degree angle, choose Show Baseline.
•
To display horizontal and vertical lines to help you align points as you drag relative to the histogram or grid, choose
Show Intersection Line.
Adjust color and tonality with Curves
You can adjust the tonality and color of an image by changing the shape of the curve in the Curves adjustment. Moving
the curve upward or downward lightens or darkens the image, depending on whether you’ve set Curves to display
levels or percentages. The steeper sections of the curve represent areas of higher contrast; flatter sections represent
areas of lower contrast.
If the Curves adjustment is set to display levels rather than percentages, the highlights are represented in the upper-
right corner of the graph. Moving a point in the top portion of the curve adjusts the highlights. Moving a point in the
center of the curve adjusts the midtones, and moving a point in the bottom section of the curve adjusts the shadows.
To darken highlights, move a point near the top of the curve downward. Moving a point either down or to the right
maps the Input value to a lower Output value, and the image darkens. To lighten the shadows, move a point near the
bottom of the curve upward. Moving a point either up or to the left maps a lower Input value to a higher Output value,
and the image lightens.
Note: In general, only small curve adjustments are necessary to make tonal and color corrections to most images.
1
Do one of the following:
•
Click the Curves icon
or a Curves preset in the Adjustments panel.