question about over operator for images with no alpha/matte channel


I’m new to Nuke but pretty familiar with the capabilities of the program.

I’m trying to learn the merge operations, starting with the Merge(over).

I understand that this operator expects a premultiplied image that is, correct me if I’m wrong, an image with an alpha channel integrated with the file.

Image A 400×400 pixels a picture of a happy face
Image B 400×400 pixels the Nuke Checkerboard

So OK, Image A has NO transparency, you can’t see through it.
I put a transform and translated Image A out of the frame ( I moved it over) and with the merge you can now see the checkerboard under it.

What I want to do is add an alpha channel to Image A to make it a premultiplied image.

Could anyone help me figure this out?

Notice how the checkerboard underneath shows through a little but with the transform it doesn’t show through the image itself, only around the sides where it was moved. Could anyone explain why that is?

Attached Thumbnails
Click image for larger version

Name:	image002.jpg
Views:	N/A
Size:	58.4 KB
ID:	7118
No Responses to “question about over operator for images with no alpha/matte channel”

Post a Comment