The Image Preview area lets you load an image or movie, then preview its RGB or Alpha channels.
When a texture is selected from the Media menu (see Media menu), the image or video file displays in the Image Preview area. For video textures, the Texture proxy plays the video clip when you play your take.
The Texture proxy can display either a texture’s RGB channels or Alpha channel.
Select either the RGB option or the Alpha option to preview the RGB channels or the Alpha channel of a loaded image.
Image Preview A. RGB option selected B. Alpha option selected