I am trying to remove some purple and green fringing from an image using Affinity Photo 1.6.5 on Windows 10, but am having no luck. I choose a live filter for defringing, and try to find a hue that matches (having slid the radius and tolerance to max and the threshold to min), but at best I get a subtle effect on the purple, and no effect on the green, no matter how many live filters I stack.
It would help if there were an eyedropper to select the color--as it is, I have to count on the filter having a visible effect in the image to see whether it's the correct color. Maybe I haven't found the color, but there are limits to how slowly I can drag the slider (and wouldn't having tolerance at max mean that the range of colors affected is large?) So, since I can't see an effect, I wind up not knowing how close to the fringe color the slider actually is. For both purple and green, I tried a number of colors that looked about right (though they didn't have a visible effect), but with little or no success.
And "Also remove complementary color" seems to have no effect.
It doesn't matter whether I try to do this in the Develop persona or the Photo persona - I get the same (lack of) effect.
The enclosed photo illustrates the problem. There is purple fringing in lots of places, including the right-hand side of the book, between the top cover and the cover jacket, and there is (out of focus, but more visible) green fringing on the left-hand side of the book, mostly on the top cover jacket itself.
I've tried various things like white balancing the photo (improves the color but the fringing remains) and using 'Select Sampled Color...' and then using it as a mask for an HSL adjustment layer to desaturate the color (some improvement, but some fringing still remains after a stack of 4 such adjustment layers.)
Using the defringing eyedroppers in an old copy of Lightroom, I can successfully defringe--but of course I don't want to use Lightroom, I want to use Affinity Photo.
Am I doing something wrong? Am I missing something?
P.S. A stack of 4 live defringing filters seems to bring Affinity to a slow crawl on my machine (a 6-core Xeon E5-1650 v3 with 32 GB of memory and an SSD running Windows 10.) This doesn't seem to happen with the other live filters I've used.
