Colormap function

The Colormap function is a type of raster data renderer. It transforms the pixel values to display the raster data as either a grayscale or a color (RGB) image based on specific colors in a color map file. You can use a color map to represent analyzed data, such as a classified image, or when displaying a topographic map (or index color scanned image).

Color maps contain a set of values that are associated with colors and are used to display a single-band raster consistently with the same colors. Each pixel value is associated with a color, defined as a set of RGB values. Color maps are capable of supporting any bit depth, except FLOAT. They can also support positive and negative values, and the color maps can contain missing color mapped values. When displaying a dataset with a color colormap containing missing values, the pixels with those missing values will not be displayed.

When the Colormap function is used, ArcGIS will display the mosaic dataset using the color map renderer

The inputs for this function are the following:

• Input Raster
• Colormap

There are several default color maps that can be chosen from the drop-down arrow; these include one for elevation data, a few used to display an NDVI image, one to display a grayscale ramp, and another to assign a random color map. You can also input a *.clr file or *.act file from Adobe Photoshop. The .clr file is an ASCII file containing the color map information for each pixel value on a separate line, formatted as "pixel_value red green blue". Below is an example of the contents of a .clr file:

1 255 0 0
2 100 0 100
3 50 200 10
4 45 60 100

You can create a .clr file from the Raster Properties dialog box; see Creating a custom CLR file.

The .act file from Adobe Photoshop is a non-ASCII file. The first color in the table has a zero index, and the color is ordered as red, green, and blue. Each color is represented by three bytes.

Note:

If the mosaic dataset is served as an image service, the publisher (admin) has an option to serve it using the color map or to convert the color map to an RGB image. The color map will automatically be converted to RGB when the image service is served using WMS or WCS.