Adobe photoshop cs2 User Manual
292
ADOBE PHOTOSHOP CS2
User Guide
The image changes to Threshold mode, and a high-contrast preview image appears. The visible areas of the image
indicate the lightest parts of the image if you are dragging the white slider, and the darkest parts if you are dragging
the black slider. If a color channel is selected in the Levels dialog box, the black area indicates where none of the given
color component exists.
indicate the lightest parts of the image if you are dragging the white slider, and the darkest parts if you are dragging
the black slider. If a color channel is selected in the Levels dialog box, the black area indicates where none of the given
color component exists.
Image preview in Threshold mode
3
Slowly drag the slider to the center of the histogram to identify areas in the image that are being clipped
(completely black or completely white). Use the pixels in these areas for targeting the black point and white point in
your image.
your image.
To identify highlights and shadows using Threshold
1
Choose Image > Adjustments > Threshold.
2
Select Preview.
3
To identify a representative highlight, drag the slider to the far right until the image becomes pure black. Drag the
slider slowly toward the center until some solid white areas appear in the image, and place a color sampler on one of
the areas. Press Shift to temporarily access the Color Sampler tool.
the areas. Press Shift to temporarily access the Color Sampler tool.
4
To identify a representative shadow, drag the slider to the far left until the image becomes pure white. Drag the
slider slowly toward the center until some solid black areas appear in the image, and place a color sampler on one of
the areas.
the areas.
5
Click Cancel to close the Threshold dialog box without applying changes to the image.
You can use the Info palette readouts of the two color samplers to determine your highlight and shadow values.
See also
To use the Exposure adjustment
The Exposure dialog box is designed for making tonal adjustments to HDR images, but it works with 8-bit and 16
bit images. Exposure works by performing calculations in a linear color space (gamma 1.0) rather than the image’s
current color space.
bit images. Exposure works by performing calculations in a linear color space (gamma 1.0) rather than the image’s
current color space.
1
Choose Image > Adjustments > Exposure.
2
Set any of the following options:
Exposure
Adjusts the highlight end of the tonal scale with minimal effect in the extreme shadows.
Offset
Darkens the shadows and midtones with minimal affect on the highlights.
Gamma
Adjusts the image gamma, using a simple power function. Negative values are mirrored around zero (that
is, they remain negative but still get adjusted as if they were positive).