CLS Filter & Photometric Colour Calibration

[STEVE333]

Richard -

I read the documentation (your link, thanks) for PCC again. It states "The Saturation threshold parameter should always be below the saturation level of the three RGB channels.". Because the R/G/B channels all saturate at at normalized value of "1", the default setting of 0.95 for the Saturation threshold should work fine.

Practically, if any of the R/G/B channels are saturated the star color will be incorrect. Thus, logically, only ONE of the channels being saturated should cause the star to be flagged. I know that the tutorial suggested setting the threshold below the lowest of the three channels, but, i'm not sure that is correct. Your Red channel is the only one that will be causing any saturation, so, that may be the only threshold that you need to worry about. I believe that is why the default threshold value is set at 0.95 not some low value.

This is just my reasoning, but, it sure seems logical.

Steve

[Scooot]

Hi Steve,

So even though the star is saturated, as indicated by the visible red blob in its linear state, PCC doesn't consider it to be saturated because the indivdual RGB channels are registering less than 1.
Therefore PCC will include it in the Colour Balance correction, particularly if I leave the saturation slider at the 0.95 default.

I wonder if it would exclude the star, or at least its red channel, which is the problem, if the slider is positioned below the red reading, in this case say 0.8 instead of 0.95? This is what I've been doing in hope  I suppose I'll never know.

Thanks for all your help.

[STEVE333]

Hi Steve,

So even though the star is saturated, as indicated by the visible red blob in its linear state, PCC doesn't consider it to be saturated because the indivdual RGB channels are registering less than 1.
Therefore PCC will include it in the Colour Balance correction, particularly if I leave the saturation slider at the 0.95 default.

I wonder if it would exclude the star, or at least its red channel, which is the problem, if the slider is positioned below the red reading, in this case say 0.8 instead of 0.95? This is what I've been doing in hope  I suppose I'll never know.

Thanks for all your help.

Your welcome Richard -

Your reasoning makes sense to me. Best of success with your processing.

Steve