|Newbie questions about Pliant
On RGB to YUV conversion
|Message posted by marcus on 2004/03/03 11:44:40
|Is there a function in Pliant to convert RGB to YUV components?
|Message posted by hubert.tonneau on 2004/03/03 11:50:18
|Color conversions are defined in module /pliant/graphic/color/color.pli
I have currently implemented sRGB, CIE Lab, CIE Lch(ab)
I have not implemented CIE Luv and CIE Lch(uv), because I don't use it for
color calibration at the moment.
What I'm wondering is do you think about 'uv' for vide or 'uv' for color
calibration. They are different because one is speed oriented and one is
|Message posted by marcus on 2004/03/03 12:10:16
|My problem concerns JPEG compression.
To achieve better compression (and also be able to use the quantization tables
currently available in the literature), one needs to convert the RGB components
of the pixel samples (in the range [0,255]) to YUV components.
I am not an expert in video, and thus have learned in
that the acrobym 'YUV' is actually misused by the PC people.
The site above provides a convertion for RGB values in the range [0,255].
I would to know a second opinion on that.
|Message posted by hubert.tonneau on 2004/03/03 12:52:14
|According to me, this is the job of the jpeg compression software.
Currenly, jpeg compression is one of the very fiew algorithm I have not ported
to Pliant, so Pliant is interfacing with the standard welknown libjpeg library.
My bet is that if converting to YUV is better for encoding, then libjpeg does
it silently, so you don't have to care.
|Message posted by marcus on 2004/03/03 14:26:37
|The reason I asked about the RGB->YUV function is because in my course the
students are asked to implement a JPEG-like encoding scheme. They need
to convert the RGB values to YUV before quantizing the samples with the
But I've tested those formulas and they produce good approximations.