Author Topic: color cast with Photometry Color Calibration and M31  (Read 1934 times)

Offline ChoJin

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color cast with Photometry Color Calibration and M31
« on: 2018 February 10 09:17:27 »
Hello,

I've been trying for hours to understand why i'm getting a huge color cast when trying the new PCC feature with my M31 data, to no avail.

I attach a screenshot of the same data processed with different setting with PCC compared to a normal color correction flow (BN+CC using the whole frame as white reference). PCC is using the same preview bbox for the BN.

I start from data integrated with localnormalization, and I only applied DBE afterward.

Once color corrected (either with BN+CC or PCC) I applied HT using the auto-STF (linked) setting, followed by SCNR (100% average neutral) and finally I (over)boost the saturation using LRGBCombination with its own L channel.

For some reasons, when I do the color correction with PCC, applying auto-STF (linked mode) yields to a huge color cast (it looks way better if I unlinked the channel).

With the classical BN+CC, I get a green cast which is killed once SCNR is applied, but with the data processed with PCC, I don't get similar results at all as you can see.

I tried to change the saturation threshold in PCC down to .25 (also from my data it seems ideally it should be set to 0.21 but I can't, the minimum is 0.25 in the UI), but I got the same results.

Am I doing something wrong or is it a corner case where BN+CC would be better?

Any help/expertize would be greatly appreciated.
« Last Edit: 2018 February 10 11:14:36 by ChoJin »

Offline ChoJin

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Re: color cast with Photometry Color Calibration and M31
« Reply #1 on: 2018 February 10 13:01:30 »
somehow, disabling BN within PCC and doing it separately just afterward yields to proper results.