How To: Create a colormap index within the attribute table of an integer raster
Instructions provided describe how to create a colormap index within the attribute table of an integer raster.
- Create a value attribute table (VAT) for the raster, if it does not already possess a VAT. This can be done using the 'Build Raster Attribute Table' tool in ArcToolbox.
- Add three new fields of type double to the raster attribute table, and name them 'Red', 'Green', and 'Blue' respectively.
- Start an edit session with the target workspace set to that of the raster.
- For each record, enter the desired RGB value in the fields named 'Red', 'Green', and 'Blue' respectively. These values need to be expressed as a percentage of 255, so a value of 50 would be 0.196078 (50/255 = 0.196078).
- Stop the editing session and save the edits to preserve the changes.
- Remove the raster layer from ArcMap's table of contents, then reload the raster back into ArcMap so the colormap can be recognized.
- Right-click on the raster in the table of contents and select Properties > Symbology tab.
- The colormap should now be available in the list of rendering options. Select the colormap renderer and click 'OK' to display the raster using the newly created colormap index.