Undoing halos and 'chroma fogging?'

[tomczak]

I'm still trying to understand the mechanism behind colour bleeding. Here is an example from Fuji X-Pro showing a similar effect. It says that it only occurs in in-camera jpegs, but in my case, the RAW, no matter how processed, carry it as well. I don't think it has anything to do with the image stabilization. What can cause is physically - I'm still wondering...

http://www.dpreview.com/reviews/fujifilm-x-pro1/16#IQ

Did anyone came across a good article or an explanation of this phenomenon?

[jsachs]

I haven't tried this, but if the problem is sensor blooming (spillover from bright areas) in a particular channel, perhaps treating that channel as a mask and feathering it with a negative radius might eliminate some of the spillover.

[tomczak]

Just to conclude (well, not quite) this lengthy quest of colour spill-over luminescence edges: I think that what I'm seeing is mostly the result of demosaicking algorithms. It seems to occur when a bluish/reddish edge, with the B or R channels at or near saturation, is 'edged' with darker, typically greenish background (such as foliage, which is common). To my mind, it occurs because the algorithm tries to fill the low intensity R and/or B photosites on a green/dark side of the edge using the R or B photosites on the bright (overexposed or nearly so in B or G channel) side of an edge. It doesn't know where to stop (i.e. at the edge), and thus overshoots.

http://chromasoft.blogspot.com/2012/05/ ... trans.html

To reduce it somewhat, the best I could figure is to either 1) turn on 'colour blur' in DPP or 2) use similar (and more adjustable) feature 'Defringe' in RawTherapee, while reducing the brightness ('exposure'). Trying various demosaicking algorithms didn't seem to make much difference.

BTW: does anybody know what the 'defringing/colour un-blur' actually does?