Bug? Color shift when translating between color modes? (jit.qt.movie)

May 24, 2012 at 9:44pm

Bug? Color shift when translating between color modes? (jit.qt.movie)

I’ve been using jit.qt.movie @colormode uyvy for high-speed transfer to the GPU, but today I noticed that it looks quite different than other methods.

This patch shows three different image pipelines for the display of YUV content:
(These are to demonstrate color, not speed.)

1) jit.qt.movie (default rgb colormode) –> jit.argb2uyvy –> jit.slab @file cc.uyvy2rgba.jxs

2) jit.qt.movie (default rgb colormode) –> jit.gl.texture

3) jit.qt.movie (uyvy colormode) –> jit.slab @file cc.uyvy2rgba.jxs

All 3 look different! It seems to me that #3 is the “right” representation of the data, since it matches Apple’s Preview app. Notably, this is the only one that uses jit.qt.movie’s uyvy mode. What method does jit.qt.movie use to convert to RGB? Am I missing something?

(MAX 6.0.5, Mac OS 10.6.8)

A color chart jpeg is attached.

– Pasted Max Patch, click to expand. –

[attachment=194723,3944]

Attachments:
  1. ColorChecker640.jpg
#59084
Apr 29, 2013 at 2:22pm

hello,
I noticed the same but for me the best result is : jit.qt.movie @colormode uyvy -> jit.gl.slab context_name @colormode uyvy

jit.slab @file cc.uyvy2rgba.jxs (or uyvy2rgba.lite or uyvy2rgba.exp) gives me a colored grey.

#212271

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