Table of Contents ▸ List of Commands ▸ Blending and Fading ▸ sub_alpha | ◀ fade_z | animate ▶ |
sub_alpha
Arguments:
- [base_image],0<=_minimize_alpha<=1
Description:
Compute the alpha-channel difference (opposite of alpha blending) between the selected imagesand the specified base image.
The alpha difference A-B is defined as the image having minimal opacity, such that alpha_blend(B,A-B) = A.
The min_alpha argument is used to relax the alpha minimality constraint. When set to 1, alpha is constrained to be minimal. When set to 0, alpha is maximal (i.e. 255).
Default values:
minimize_alpha=1.
Example of use:
image.jpg testimage2d {w},{h} +sub_alpha[0] [1] display_rgba