Touring the Interface with a Basic Composite - Nuke 101: Professional Compositing and Visual Effects - page 40

3. Select Merge1 and press 1 on the keyboard to view the result in the Viewer
( FIGURE 2.8 ) .
Figure 2.8. All this light purple discoloration wasn't here before.
The image, however, looks wrong—it is washed out in an odd light purple color.
Maybe you don't have an alpha channel? Let's have a look.
4. Click Read2 and press 1 on the keyboard to view it in the Viewer.
5. While hovering your mouse pointer over the Viewer, press the A key to view the
alpha channel ( FIGURE 2.9 ) .