Functions

AFAPI array ycbcr2rgb (const array &in, const YCCStd standard=AF_YCC_601)
 C++ Interface for converting YCbCr to RGB. More...
 
AFAPI af_err af_ycbcr2rgb (af_array *out, const af_array in, const af_ycc_std standard)
 C Interface for converting YCbCr to RGB. More...
 

Detailed Description

YCbCr to RGB colorspace converter

YCbCr is a family of color spaces used as a part of the color image pipeline in video and digital photography systems where Y is luma component and Cb & Cr are the blue-difference and red-difference chroma components.

RGB (Red, Green, Blue) is the most common format used in computer imaging. RGB stores individual values for red, green and blue, and hence the 3 values per pixel. A combination of these three values produces the gamut of unique colors.

Input array to this function should be of real data with the following range in their respective channels.

\(Y -> [16, 219]\)

\(Cb-> [16, 240]\)

\(Cr-> [16, 240]\)

The following equations are used to convert image from RGB color space to YCbCr color space.

\( R = \frac{\displaystyle Y - \displaystyle 16}{\displaystyle 219} + \frac{\displaystyle C_r - \displaystyle 128}{\displaystyle 112} * (\displaystyle 1 - \displaystyle k_r) \)

\( G = \frac{\displaystyle Y - \displaystyle 16}{\displaystyle 219} - \frac{\displaystyle C_r - \displaystyle 128}{\displaystyle 112} * (\displaystyle 1 - \displaystyle k_r) * \frac{\displaystyle k_r}{\displaystyle 1 - \displaystyle k_b - \displaystyle k_r} - \frac{\displaystyle C_b - \displaystyle 128}{\displaystyle 112} * (\displaystyle 1 - \displaystyle k_b) * \frac{\displaystyle k_b}{\displaystyle 1 - \displaystyle k_b - \displaystyle k_r}\)

\( B = \frac{\displaystyle Y - \displaystyle 16}{\displaystyle 219} + \frac{\displaystyle C_b - \displaystyle 128}{\displaystyle 112} * (\displaystyle 1 - \displaystyle k_b) \)

Output image in RGB will have values in range \([0, 1]\).

Based on the ITU-R BT.xyz[w] standard used, different values of \(k_b\) and \(k_r\) are used to do the color space conversion. You can change these values by passing the af_ycc_std enum value.


Function Documentation

◆ af_ycbcr2rgb()

AFAPI af_err af_ycbcr2rgb ( af_array out,
const af_array  in,
const af_ycc_std  standard 
)

C Interface for converting YCbCr to RGB.

Parameters
[out]outis an array in the RGB color space
[in]inis an array in the YCbCr color space
[in]standardspecifies the ITU-R BT "xyz" standard which determines the Kb, Kr values used in colorspace conversion equation
Returns
AF_SUCCESS if the color transformation is successful, otherwise an appropriate error code is returned.
Note
in must be three dimensional and values should lie in the range [0,1]

◆ ycbcr2rgb()

AFAPI array af::ycbcr2rgb ( const array in,
const YCCStd  standard = AF_YCC_601 
)

C++ Interface for converting YCbCr to RGB.

Parameters
[in]inis an array in the YCbCr colorspace
[in]standardspecifies the ITU-R BT "xyz" standard which determines the Kb, Kr values used in colorspace conversion equation
Returns
array in RGB colorspace
Note
in must be three dimensional and values should lie in the range [0,1]