[Interest] QVideoFrame and YUV question

[Thiago Macieira]

Em sex 14 mar 2014, às 08:47:15, Jason H escreveu:
> The frame is not laid out like RGB. This is for legacy reasons. Black and
> White TV presented a black and white frame (Y) when color TV was added, it
> was added in a backwards-compatible way

This has nothing to do with black & white TV. Digital image formats were 
invented way after colour TV.

The reason why Y is sampled per pixel whereas U and V aren't is because the 
eye isn't as sensitive to colour as it is to luminosity. By using one U and 
one V for 4 pixels, we reduce the amount of data from 12 values to 6 in each 
2x2 block -- that is, half the amount of data.

There are some other YUV formats that lay out data differently, including all 
the chrominance values, like YUV 4:4:4.
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center