Non-linear masking examples
Billy Biggs <email@example.com>
For some more background on this page, see the parent page on non-linear masking.
Recently my friend Tony went to Amsterdam and Japan, taking a lot of photos. Some came out too dark, and so I used them for experimenting with colour correction methods.
I used two techniques. Both of these use the lightness of the image to decide how to correct it. One method is completely based on operations in CIECAM02, and the other is just a function on the gamma-corrected RGB values, but using the lightness function from the IPT colourspace.
Unfortunately, the CIECAM02-based images, which I thought would look better, seem to appear too bright for many of the darker images. Maybe this is because I am not using the surround and background attributes to my advantage?
This shot clearly needed some adjustment, but the CIECAM02 version had more halo artifacts than we would have liked.
An example where the correction really helps and any halos end up looking natural.