Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference
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AlphaPremulC
Pre-multiplies pixel values of an image using constant alpha (opacity) values.
Syntax
Case 1: Not-in-place operation
IppStatus ippiAlphaPremulC_<mod>(const Ipp<datatype>* pSrc, int srcStep, Ipp<datatype> alpha, Ipp<datatype>* pDst, int dstStep, IppiSize roiSize);
Supported values for mod :
| 8u_C1R | 16u_C1R | 
| 8u_C3R | 16u_C3R | 
| 8u_C4R | 16u_C4R | 
| 8u_AC4R | 16u_AC4R | 
IppStatus ippiAlphaPremulC_<mod>(const Ipp<datatype>* const pSrc[4], int srcStep, Ipp<datatype> alpha, Ipp<datatype>* const pDst[4], int dstStep, IppiSize roiSize);
Supported values for mod :
| 8u_AP4R | 16u_AP4R | 
Case 2: In-place operation
IppStatus ippiAlphaPremulC_<mod>(Ipp<datatype> alpha, Ipp<datatype>* pSrcDst, int srcDstStep, IppiSize roiSize);
Supported values for mod :
| 8u_C1IR | 16u_C1IR | 
| 8u_C3IR | 16u_C3IR | 
| 8u_C4IR | 16u_C4IR | 
| 8u_AC4IR | 16u_AC4IR | 
IppStatus ippiAlphaPremulC_<mod>(Ipp<datatype> alpha, Ipp<datatype>* const pSrcDst[4], int srcDstStep, IppiSize roiSize);
Supported values for mod :
| 8u_AP4IR | 16u_AP4IR | 
Include Files
ippi.h
Domain Dependencies
Headers: ippcore.h, ippvm.h, ipps.h
Libraries: ippcore.lib, ippvm.lib, ipps.lib
Parameters
| pSrc | Pointer to the source image ROI for pixel-order data. An array of pointers to ROI in the separate source color planes in case of planar data. | 
| srcStep | Distance in bytes between starts of consecutive lines in the source image. | 
| pDst | Pointer to the destination image ROI for pixel-order data. An array of pointers to separate ROI in the destination color planes in case of planar data. | 
| dstStep | Distance in bytes between starts of consecutive lines in the destination image. | 
| pSrcDst | Pointer to the source and destination image ROI or an array of pointers to ROI in the separate source and destination color planes for the in-place operation. | 
| srcDstStep | Distance in bytes between starts of consecutive lines in the source and destination image for the in-place operation. | 
| roiSize | Size of the source and destination ROI in pixels. | 
| alpha | Global alpha value used for pre-multiplying pixel values. | 
Description
This function operates with ROI (see Regions of Interest in Intel IPP).
This function converts either a one-, three-, four-channel image or planar RGBA image to the pre-multiplied alpha form, using the global alpha value alpha. For one-, three-, four-channel image buffers, pixel values in each channel are multiplied by α; for RGBA (pixel order and planar) images with (r,g,b,a) pixel values, new pixel values are (r*α, g*α, b*α, alpha) after execution of this function. Here α is the normalized alpha value in the range 0 to 1.
The function ippiAlphaPremulC can be used for unsigned pixel data only.
Return Values
| ippStsNoErr | Indicates no error. Any other value indicates an error or a warning. | 
| ippStsNullPtrErr | Indicates an error condition if one of the specified pointers is NULL. | 
| ippStsSizeErr | Indicates an error condition if roiSize has a field with zero or negative value. |