Developer Reference

  • 2020
  • 10/21/2020
  • Public Content
Contents

RGBToGray

Converts an RGB image to gray scale using fixed transform coefficients.

Syntax

IppStatus ippiRGBToGray_<mod>(const Ipp<datatype>*
pSrc
, int
srcStep
, Ipp<datatype>*
pDst
, int
dstStep
, IppiSize
roiSize
);
Supported values for
mod
:
8u_C3C1R
16u_C3C1R
16s_C3C1R
32f_C3C1R
8u_AC4C1R
16u_AC4C1R
16s_AC4C1R
32f_AC4C1R
Include Files
ippcc.h
Domain Dependencies
Headers:
ippcore.h
,
ippvm.h
,
ipps.h
,
ippi.h
Libraries:
ippcore.lib
,
ippvm.lib
,
ipps.lib
,
ippi.lib
Parameters
pSrc
Pointer to the source image ROI.
srcStep
Distance in bytes between starts of consecutive lines in the source image.
pDst
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.
Description
This function operates with ROI.
Conversion from RGB image to gray scale (see figure
Converting an RGB Image to Gray Scale
) uses the following basic equation to compute luma from nonlinear gamma-corrected red, green, and blue values:
Y' = 0.299 * R' + 0.587 * G' + 0.114 * B'
. Note that the transform coefficients conform to the standard for the NTSC red, green, and blue CRT phosphors.
Converting an RGB Image to Gray Scale
Return Values
ippStsNoErr
Indicates no error. Any other value indicates an error.
ippStsNullPtrErr
Indicates an error condition if
pSrc
or
pDst
pointer is
NULL
.
ippStsSizeErr
Indicates an error condition if
roiSize
has a field with a zero or negative value.

Example

The code example below demonstrates how to use the function
ippiRGBToGray_8u_C3C1R
.
Ipp8u src[12*3] = { 255, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 255}; Ipp8u dst[4*3]; IppiSize srcRoi = { 4, 3 }; ippiRGBToGray_8u_C3C1R ( src, 12, dst, 4, srcRoi );
Result:
255 0 0 255 0 0 255 0 0 255 0 0 0 255 0 0 255 0 0 255 0 0 255 0 src 0 0 255 0 0 255 0 0 255 0 0 255 76 76 76 76 149 149 149 149 dst 29 29 29 29

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804