YV12 to RGB color problem

[wydesenej]

Hi,
iam using unix avifile lib to convert YV12 Divx frame to RGB.

I attach image of my outup. Left image is real frame from video and right image is my output.
If you have any suggestions to solve this problem please post.

Thx,
wydesenej

colors.png

[pandy]

arithmetic without saturation - enable clamp, choose different color space coefficients

more on this http://en.wikipedia.org/wiki/Saturation_arithmetic

also problem with chroma planes (swapped Cb with Cr? looks like NOT or XOR values)

[jagabo]

It looks like your luma channel is being multiplied by 2 and isn't being clamped -- ie, when values go above 255 they are wrapping back down to 0. It also looks like the chroma channels are reversed. Here's your left image with the chroma channels reversed, converted to RGB, then all primaries multiplied by 2 (with clamping):



Notice how all the dark areas are the same as your right image. The light areas are clamped here so they don't wrap around to black, they're just full out white.