Why is Open Attribute Table in ArcMap unavailable for some raster datasets?

Answer

In ArcGIS Desktop 9.2 and later, the Open Attribute Table function in ArcMap is unavailable for some raster datasets when they do not contain a raster attribute table.

In ArcGIS Desktop 9.1, when a raster dataset that does not contain an attribute table is added to ArcMap, the system automatically scans all pixel values and builds a raster attribute table on-the-fly, if the table size is within certain limits.

The mechanism to automatically build a raster attribute table is not available in ArcGIS Desktop 9.2, as scanning all pixel values to build a raster attribute table on-the-fly is unnecessary if the unique value renderer is not used for displaying raster data in images that are getting larger.

To add a raster attribute table in ArcGIS Desktop 9.2 and 9.3.x:

1. Use the Build Raster Attribute Table geoprocessing tool in the Data Management > Raster toolset.
2. Once the table exists, the Open Raster Attribute Table function in ArcMap can be used.

To add a raster attribute table in ArcGIS Desktop 10.1 and above:

1. In ArcMap or ArcCatalog, click ArcToolbox > Data Management Tools > Raster > Raster Dataset > Copy Raster.
2. In the Copy Raster window, Pixel Type (optional) drop-down, select the 32_BIT_SIGNED integer. This converts the 32-bit floating point raster to a 32-bit signed integer raster.
3. Click ArcToolbox > Data Management Tools > Raster > Raster Properties > Build Raster Attribute Table.
4. Specify the 32-bit signed integer output raster from Step 2 as the input raster. The output raster has an attribute table.

Note:
For developers, use IRasterDatasetEdit2 and BuildAttributeTable to force the creation of a raster attribute table.