Magenta edge tinging at high ISO and a possible solution...

Started Aug 17, 2009 | Discussions thread
GordonBGood Veteran Member • Posts: 6,308
Re: PROGRESS:Almost finished, BUT...

To all,

I have tested the algorithm as I described and tested it vertically on the sample DNG's a couple of you have sent me. As far as I can tell it is doing what I planned to have it do and it is removing the colour tinged borders top and bottom but it seems that my expectation that the response from the center of the sensor towards the edges is not a straight line and the correction is thus not correct across the whole frame.

It looks like I am going to have to spend a little more time trying to understand what the relationship curve is, at least for this vertical response, which will take at least another half day or so. I'll first try to model it with a quadratic.

I am trying not to apply the determined relative offset from the sliding window as a correction, which is more or less what the effect is of Dominique's (dlacoutu's) method, as this will likely add to the Horizontal Pattern Noise (HPN). A best fit curve won't add a variable component to the row corrections and thus won't add HPN to the image.

It should be noted that the correction I am doing is still quite small, even in an ISO 6400 image, such that the magnitude of the tingeing is change down at about the six or seven stops below full bright level, so just at about the limit of what we see as visible in a full DR image with both dark and bright tones.

Regards, GordonBGood

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