An alpha band acts as a transparency mask, providing a transparency value for each pixel. An alpha band can be toggled on or off for multiple-band raster datasets rendered with the RGB Composite renderer.
- Right-click the raster layer you want to change the alpha band for in the table of contents and click Properties.
- Click the Symbology tab.
- Click RGB Composite.
- To turn the alpha band on, check the Alpha channel box and choose a band to use.
To turn the alpha band off, uncheck the box for the Alpha channel.
- Click OK.