HSL-HS 2D histogram

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tomczak
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Joined: April 25th, 2009, 12:56 am
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HSL-HS 2D histogram

Post by tomczak »

I was trying to understand better how the 2D histograms work by trying them on the Colour Hexagon test image. I think I understand how the HSV-HV operates, but I'm having trouble wrapping my brain around the HSL-HS one. In HSL-HS histogram, all the colours in the Hexagon are the surface of the upper cone - i.e. fully saturated regardless of Lightness. But why probing on them shows red marks for less saturated colours? Is it because the probe registers H and S of the point and sets L to 50%?
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Maciej Tomczak
Phototramp.com

jsachs
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Re: HSL-HS 2D histogram

Post by jsachs »

Yes, the probe was not working correctly for HSL-HS. Fixed for next release.
Jonathan Sachs
Digital Light & Color

tomczak
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Re: HSL-HS 2D histogram

Post by tomczak »

Also, and I understand it's a synthetic image with only saturated colours, if the expansion factor is left at 1, the colours of 'dots' on the 2D histograms are almost black. I would expect that if there was some colour peak that would dwarf all the others, but shouldn't they have been all about equal?
Maciej Tomczak
Phototramp.com

jsachs
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Re: HSL-HS 2D histogram

Post by jsachs »

There is a single, very large spike in the histogram corresponding to the black background. This shows up as a white dot in the center of the hs histogram.
Jonathan Sachs
Digital Light & Color

tomczak
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Joined: April 25th, 2009, 12:56 am
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Re: HSL-HS 2D histogram

Post by tomczak »

Ah, thank you.
Maciej Tomczak
Phototramp.com

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