The background area in each of the bands you are displaying must contain the same value to be used with this functionality. To find the value of the background cells, click the Identify button on the Tools toolbar, then click on the background cells in the raster layer.
- In ArcMap, in the table of contents, right-click the raster layer for which you want to hide the background and click Properties.
- Click the Symbology tab.
- Choose either the RGB Composite or Stretched renderer.
- Check Display Background Value and type in the value of the background.
- Set the color to No Color.
- Click OK.
The cells display transparently.