previews of color changes should work on the displayed image, not on the full image
Submitted by Raphaël Quinet
When previewing the result of some color transformations (curves, levels, brightness, etc.), the preview should work on the displayed image instead of using the tiles from the original image.
So if the GIMP caches a scaled-down preview of the image (bug #76096), the color transformations could be previewed much faster. See also bug #90421. Being able to update a preview based on the displayed image would be useful for the tools listed above. This would also be useful for all plug-ins dealing with colors, if the preview image is made accessible through the PDB.
Version: git master