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Bug in Hue/Saturation


KrisVDM
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Something seems wrong with the accuracy of the Hue/Saturation adjustment. Take any photograph, and apply the adjustment about 6 times, with parameters Hue = 0, Saturation = 200, Lightness = 0. You’ll notice that only primary and secondary colors remain, i.e. colors where r, g and b are either 0 or 255. I would expect the full range of hues to remain; only saturation should have increased.

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Probably just a precision and quantization artifact.
That's exactly what I mean. The quantization is visible after one run though, it just becomes very obvious after multiple runs. Can it not be fixed, now that 3.5 is stabilizing? This is one of those things that make me consider shooting all photo's in RAW and using Digital Photo Professional...
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Wasn't there a post somewhere about the quantization artifacts in the HsvColor class? That's what the HSL adjustment is based on. I never got around to examining that because I was busy at the time ... whenever that was.

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Can it not be fixed, now that 3.5 is stabilizing?

This is actually one of the best times to fix it. I'm fixing some outlier bugs for v3.5.2. Anything that doesn't affect localization and that has either good end-user impact or low development risk is a good candidate. This sounds like it could fit both.

This is one of those things that make me consider shooting all photo's in RAW and using Digital Photo Professional...

Well, if you're really serious about photography then you really should consider that :) Or some Photoshop setup. (I'm not familiar with Digital Photo Pro, but I do have CS4)

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if you're really serious about photography then you really should consider that :) Or some Photoshop setup. (I'm not familiar with Digital Photo Pro, but I do have CS4)
I do have Photoshop, and DPP (the RAW editing software that comes with Canon cameras, you can download it from their site too - it's free). I use them, mostly DPP, for those photo's I shot in RAW, and today that's a minority. I tend to prefer and use Paint.NET for all JPEG work, because it's faster and easier to use. And if needed, I can program my own custom adjustment in minutes, which I cannot with the others. And then there's all the non-photo stuff too.

I guess what I'm saying is, is that I won't stop using Paint.NET any time soon, whether you work on that saturation thing or not.

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Here's the post I was looking for, viewtopic.php?f=27&t=23593
There you have it, the code is already written! Should be trivial to include now. Unless you want to revisit all places where ColorHsv is used... But be careful, as that would be a breaking change to plugins. I suppose a ColorHsv2 or something could solve that.

Anyway, thanks for looking into this.

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