RGBToY_JPEG

Converts an RGB image to gray scale.

Syntax

Case 1: Operation on planar data

IppStatus ippiRGBToY_JPEG_8u_P3C1R(const Ipp8u* pSrcRGB[3], int srcStep, Ipp8u* pDstY, int dstStep, IppiSize roiSize);

Case 2: Operation on pixel-order data

IppStatus ippiRGBToY_JPEG_8u_C3C1R(const Ipp8u* pSrcRGB, int srcStep, Ipp8u* pDstY, int dstStep , IppiSize roiSize);

pSrcRGB	Pointer to the source image ROI.
srcStep	Distance in bytes between starts of consecutive lines in the source image.
pDstY	Pointer to the destination image ROI.
dstStep	Distance in bytes between starts of consecutive lines in the destination image.
roiSize	Size of the source and destination ROI in pixels.

The function ippiRGBToY_JPEG is declared in the ippj.h file. It operates with ROI (see Regions of Interest in Intel IPP).

This function converts the RGB image to gray scale using the following formula:

Y = 0.299*R + 0.587*G + 0.114*B

Example “Using the function ippiRGBToY_JPEG” shows how to use the function ippiRGBToY_JPEG_8u_C3C1R.

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers is NULL.
ippStsSizeErr	Indicates an error condition if roiSize has a field with zero or negative value.
ippStsStepErr	Indicates an error condition if srcStep or dstStep has a zero or negative value.

Ipp8u srcRGB[9*3] = { 255, 0, 0, 255, 0, 0, 255, 0, 0,

                      0, 255, 0, 0, 255, 0, 0, 255, 0,

                      0, 0, 255, 0, 0, 255, 0, 0, 255};

Ipp8u dstY[3*3];

IppiSize roiSize = { 9, 3 };

ippiRGBToY_JPEG_8u_C3C1R ( srcRGB, 9, dstY, 9, roiSize );

result:

255 0   0   255 0   0   255 0   0

0   255 0   0   255 0   0   255 0        src

0   0   255 0   0   255 0   0   255

 76  76  76

150 150 150        dst

 29  29  29