YCbCr to RGB from matrix table.

Question

Hi Below is a matrix to convert YCbCr to RGB, Can you tell me how can I get formula to convert YCbCr to RGB? I mean, I have YCbCr value available and I want to get RGB from it.

Answer 1

Y = 0.2126*(219/255)*R + 0.7152(219/255)*G + 0.0722*(219/255)*B + 16
CB = -0.2126/1.18556*(224/255)*R - 0.7152/1.8556(224/255)*G + 0.5*(219/255)*B + 128
CR = 0.5*(224/255)*R - 0.7152/1.5748(224/255)*G - 0.0722/1.5748*(224/255)*B + 128

Answer 2

http://www.fourcc.org/fccyvrgb.php has YUV to RGB conversions.

Answer 3

If you are asking how the formula is derived, you may want to search for "color coordinate systems". This page has a good discussion on the YCbCr space, in particular.

We know that almost any color can be represented as a linear combination of red, green, and blue. But you can transform (or "rotate") that coordinate system such that the three basis elements are no longer RGB, but something else. In the case of YCbCr, the Y layer is the luminance layer, and Cb and Cr are the two chrominance layers. Cb correlates more closely to blue, and Cr correlates more closely to red.

YCbCr is often preferred because the human visual system is more sensitive to changes in luminance than quantitatively equivalent changes in chrominance. Therefore, an image coder such as JPEG can compress the two chrominance layers more than the luminance layer, resulting in a higher compression ratio.

EDIT: I misunderstood the question. (You should edit it to clarify.) Here is the formula to get RGB from YCbCr, taken from the above link:

r   =   1.0 * y'    + 0 * cB    + 1.402 * cR
g   =   1.0 * y'    - 0.344136 * cB - 0.714136 * cR
b   =   1.0 * y'    + 1.772 * cB    + 0 * cR

Answer 4

I'm not going to account for the round portion, but since M looks invertible:

You can round the resulting vector.