Hue Saturation Transformation Issues

[jfoster]

First, Brightness Change doesn't seem to work. To reproduce:

1. Open PWP (8.0.297)
2. Open Hue Saturation Test Pattern
3. Select a region of the image
4. Note that for Brightness Change values of everything other than -100% no change occurs to the selected regions of the output image. Also note that the value of -100% results in black output area.

Second, the Hue Change doesn't seem to work correctly. To reproduce:

1. Open PWP (8.0.297)
2. Open Hue Saturation Test Pattern
3. Select a complete horizontal band of blocks in the test pattern (in upper half of the pattern to clearly see the issue)
4. Use the Hue Change control to rotate the colors
5. Note that the red values are not affected by Hue Change transform

And finally, is it intended behavior for the Show Affected Region feature to display the non-transformed image portions in the Preview Window? Intuitively to me it would seem appropriate for the Affected Region, still visible in the Preview Image, to still show the effects of the transforms.

Jeff

[jsachs]

As to the first point, this is expected behavior since the Hue Saturation Chart has all patches with HSV brightness 100% and the brightness adjustment preserves 0% and 100%, until you set it to -100%. For normal photographic images, this works well -- the test pattern is an atypical special case.

I fixed the second problem for the next release although it only affected colors that were exactly 100% red.

It was intentional that Show Affected Region not show the results of the transformation -- it is mostly intended as an aid in seeing what parts of the input image are being change, but I can see how that might be unexpected so I changed it for the next release.

[jfoster]

Got it. Thanks.

Jeff

[jfoster]

This is the first I've had a chance to play around with this Transformation. Another thing I've noticed is that maxing out the Saturation Change slider results in pure white pixels (255, 255, 255) turning red.

Jeff

[jsachs]

This is another artifact of the HSV and HSL color spaces. By definition, neutral colors white..gray..black all have saturation 0 and hue 0. The hue is actually undefined but is arbitrarily set to 0. If you then force the saturation to something other than 0%, the arbitrary hue of 0% (which equals red) makes neutrals red.

[jfoster]

Should of known that. Thanks again.

Jeff