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Basic Photo Corrections

  • Sample Chapter is provided courtesy of Adobe Press.
  • Date: Jun 26, 2006.

Removing a color cast

Some images contain color casts (imbalanced colors), which may occur during scanning or which may have existed in the original image. This photograph of the window has a blue cast. You’ll use the Auto Color feature in Photoshop 7.0 to correct this. (ImageReady does not include the Auto Color command, so this task must be done in Photoshop.)

NOTE

To see a color cast in an image on your monitor, you need a 24-bit monitor (one that can display millions of colors). On monitors that can display only 256 colors (8 bits), a color cast is difficult, if not impossible, to detect.

coloursection_icon.gif

For an illustration of color casting, see figure 3-1 in the color section.

  1. Choose Image > Adjustments > Auto Color.

    Notice that the blue color cast is gone.

  2. Choose File > Save.

Using the Auto Color command (Photoshop)

The Auto Color command adjusts the contrast and color of an image by searching the actual image rather than the channels’ histograms for shadows, midtones, and highlights. It neutralizes the midtones and clips the white and black pixels based on the values set in the Auto Correction Options dialog box.

Setting auto correction options (Photoshop)

The Auto Correction Options dialog box lets you automatically adjust the overall tonal range of an image, specify clipping percentages, and assign color values to shadows, midtones, and highlights. You can apply the settings during a single use of the Levels dialog box or Curves dialog box, or you can save the settings for future use with the Levels, AutoLevels, Auto Contrast, Auto Color, and Curves commands.

To open the Auto Correction Options dialog box, click Options in the Levels dialog box or Curves dialog box.

–From Adobe Photoshop 7.0 online Help

7. Replacing colors in an image | Next Section Previous Section

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