The following pages are intended to be a brief overview of the Photoshop 6.0 program for the educational benefit of the Art and Photography students of Moeller High School.  All images and information are derived from the Adobe Photoshop Help Pages.  For complete information please follow the link to the Adobe Photoshop 6.0 Help page.

Making quick overall adjustments to an image

  The Brightness/Contrast, Auto Levels, Auto Contrast, and Variations commands change colors or tonal values in an image but are not as precise or flexible as the high-end color adjustment tools. They provide a quick and simple way to make overall adjustments.

Using the Brightness/Contrast command

  The Brightness/Contrast command lets you make simple adjustments to the tonal range of an image. Unlike Curves and Levels, this command makes the same adjustment to every pixel in the image. The Brightness/Contrast command does not work with individual channels and is not recommended for high-end output, because it can result in a loss of detail in the image.

To use the Brightness/Contrast command:

1 Open the Brightness/Contrast dialog box. (See Making color adjustments.)

2 Drag the sliders to adjust the brightness and 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 Click OK.

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Applying special color effects to images

The Desaturate, Invert, Equalize (Photoshop), Threshold (Photoshop), and Posterize (Photoshop) commands 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 by blending colors from different channels. (See Mixing color channels (Photoshop).)

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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 > Adjust > Desaturate.

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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 > Adjust > Invert, or choose Layer > New Adjustment Layer > Invert (Photoshop).