Method Image.Image()->rgb_to_yuv()

Method rgb_to_yuv
Method yuv_to_rgb

object rgb_to_yuv()
object yuv_to_rgb()

Description

Converts RGB data to YUV (YCrCb) data, or the other way around. When converting to YUV, the resulting data is stored like this: pixel.r = v (cr); pixel.g = y; pixel.b = u (cb);

When converting to RGB, the input data is asumed to be placed in the pixels as above.

original	->yuv_to_rgb();	->rgb_to_yuv();
tuned box (below)	the rainbow (below)	same, but rgb_to_yuv()

RGB to YUB calculation (this follows CCIR.601):

in = input pixel
out = destination pixel
Ey = 0.299*in.r+0.587*in.g+0.114*in.b
Ecr = 0.713*(in.r - Ey) = 0.500*in.r-0.419*in.g-0.081*in.b
Ecb = 0.564*(in.b - Ey) = -0.169*in.r-0.331*in.g+0.500*in.b
out.r=0.875*Ecr+128
out.g=0.86*Ey+16
out.b=0.875*Ecb+128

Example: Nice rainbow.

 object i = Image.Image(200,200);
 i = i->tuned_box(0,0, 200,200,
                  ({ ({ 255,255,128 }), ({ 0,255,128 }),
                     ({ 255,255,255 }), ({ 0,255,255 })}))
      ->yuv_to_rgb();
 

Returns

the new image object