Monday, November 26, 2007

How to work with Arithmetic

How to work with Arithmetic

To work with Arithmetic

To use the Image Arithmetic dialog box:

a) Function New Color Value Equals

      Add Image 1 Value + Image 2 Value

      Subtract Image 1 Value - Image 2 Values

      Multiply Image 1 Value x Image 2 Value

      Difference Absolute Value of (Image 1 Value - Image 2 Value)

      Lightest Maximum of (Image 1 Value, Image 2 Value)

      Darkest Minimum of (Image 1 Value, Image 2 Value)

      Average (Image 1 value + Image 2 Value)

b) From the Channel panel, select the color channels to combine:

  • Select the "All channels" check box to use all the color channels in both images. This will produce a 24-bit image.

  • Select a specific channel for each image to produce a grayscale image.

c) Set the Divisor and Bias modifiers. The modifiers are applied to the color values produced by the Formula and the Channel selections.

  • The Divisor number is used to divide the color values. It can reduce the effects of the other selections.

  • The Bias number shifts each color value by a fixed amount. The number is added to the color value produced by the Formula, Channel, and Divisor selections.

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