Removing the background area of a raster layer using the Unique Values renderer

Steps:

1. In ArcMap, in the table of contents, right-click the raster layer from which you want to remove the background and click Properties.
2. Click the Symbology tab and click Unique Values from the Show list.
3. Click the symbol that represents background (usually with a value of zero).
4. Click Remove.
5. Click Apply.

   The background cells are removed and, therefore, will not be displayed. To put them back, click Add All Values.

6. Click OK.

Tip:

You can choose to hide the background color by displaying it transparently. Right-click the background color in the table of contents and choose No Color.