New!! - Bleach Bypass filter

[Didée]

I'm not quite sure what you are seeing, to me those pics look good. Perhaps it is simply a display issue - what kind of display are you using? TFT panel? Possible to make a true screenshot with a camera?

[WorBry]

I'm seeing a lighter vertical band in the upper range (right side) of both spectra. Thought it might be some VDub quirk, but if you are not seeing it in the upoaded pics, maybe it is my display. I'm on my laptop. Unfortunately, I dont have a camera with me. Screen capture predictably shows the same. I'll play around with my display settings meanwhile. Cheers.


Edit: Here's a composite U & V spectrum (VSpec rotated left 45 deg). If you cant see the cross-banding on that one, it must surely be my display.

http://www.mediafire.com/file/mfzyrjztdjy/UV_Composite_Spectrum.png

[Gavino]

I think I understand what you're referring to now.
Taking the USpec for example, and looking at the RGB values in AvsP, the blue ranges from 0 to 255, but the variation is confined to a central band with bands of constant 0 on the left and constant 255 on the right. This is irrespective of adding ConvertToRGB32("PC.601") or not, although this probably changes the relative sizes of the three regions.

I think the explanation is that you have proper U and V gradients (as the histograms show), but on conversion to RGB you get clipping on the ranges of B (for U) or R (for V). This is because the range of U (and V) which produces valid RGB also depends on the value of Y, as can be seen from the formulae on this page (http://avisynth.org/mediawiki/Color_conversions).

[WorBry]

If that's the explanation - then what to do, or should I just take it that the spectra are valid in the context of YV12 processing, if not RGB display?

Edit: Cant find any adjustment to my laptop display that makes a difference. Tried coring (16 - 235) the source greyscale gradient, and the output U and V spectra (using Levels, which also clips the chroma) - same thing. On converting the U and V spectra back to luma, there's no clipping of the luma gradient. So I'm inclined to think you are right about the 'Y' factor, as it relates to RGB rendering of UV chroma.

That's why it also is important to avoid luma 'overflow' (rippling) in the blend formulae - luma aberration translates to colour aberration.

[WorBry]

@Gavino,

I replied to your post (new thread) on the subject of 'RGB invalid' YUV chroma:

http://forum.doom9.org/showthread.php?p=1402323#post1402323