This tutorial shows you how to use the Palette Manager to alter the visual appearance of images. When you complete this tutorial you should be able to:
- Change colors in the image to new colors for better effect or to hide undesirable features.
- Combine colors in a map to isolate features of interest.
- Convert a grayscale image to color and add special effects for presentation purposes.
- Assign a transparent color to an image.
- Combine colors in an image to improve its appearance.
- Compress the image palette to eliminate unused palette entries.
The Palette Manager works with grayscale and palette color images of 8-bit format (256 colors). The image palette is shown graphically in the dialog box and can be sorted in different ways, making it easier to work with. You can combine or change individual colors. Change operations modify only the palette itself whereas Combine operations operate on the actual image data. The Compress operation eliminates unused colors and cleans up the palette. Compressing an image palette typically modifies both the palette as well as the image data.
This tutorial consists of three exercises. Each one uses a different image type and covers typical palette operations for that image type:
- Scanned USGS map. Modify a map from the United States Geological Survey using palette controls to hide a feature by changing its color to match the background. Combine features by changing them to a single color. Isolate a feature by changing the color of everything else to match the background.
- Grayscale aerial photo. Modify a photo for presentation purposes, using an external palette in order to emphasize specific areas within the project boundary.
- Color satellite image. Assign a transparent color, combine several colors to consolidate the display of a feature, and compress the palette to eliminate unused entries.