What do PP defringing tools/plugins do, exactly?

What do tools to remove chromatic aberration actually do, anyway?

Are they just looking for high-contrast lines and then kill colors they know to be involved in fringing?

Well you could try a little experiment. Open an image in LR/ACR and go to the defringe tool. Set the colour values to be fairly wide apart in the blue/purple/red and set a large value. When you look at the result it becomes obvious that there is quite a bit of processing at play, other than simply desaturating the edges. What they are doing is beyond my knowlege though.

Alan

uOpt wrote in post #15870784
What do tools to remove chromatic aberration actually do, anyway?

Are they just looking for high-contrast lines and then kill colors they know to be involved in fringing?

I'm sure its a lot more complicated than that! I've been reading about noise reduction and had not realised how complex that subject is.

uOpt wrote in post #15870784
What do tools to remove chromatic aberration actually do, anyway?

Lateral or longitudinal?
ACR/LR does quite well on Lateral CA.

http://www.cambridgein​colour.com …ials/lens-corrections.htm
http://www.image-engineering.de …ntent&view=arti​cle&id=510