Add experimental overlayWith API

Composites an overlay image with alpha channel into the input image (which
must have alpha channel) using ‘over’ alpha compositing blend mode. This API
requires both images to have the same dimensions.

References:
- http://en.wikipedia.org/wiki/Alpha_compositing#Alpha_blending
- https://github.com/jcupitt/ruby-vips/issues/28#issuecomment-9014826

See #97.
This commit is contained in:
Daniel Gasienica
2015-04-24 14:57:48 -07:00
committed by Lovell Fuller
parent c886eaa6b0
commit 64f7f1d662
17 changed files with 312 additions and 8 deletions

Binary file not shown.

After

Width:  |  Height:  |  Size: 136 KiB