SampleDownRowH2V1_Box

Performs 2:1 horizontal sampling and 1:1 vertical sampling of an image row.

Syntax

IppStatus ippiSampleDownRowH2V1_Box_JPEG_8u_C1(const Ipp8u* pSrc, int srcWidth, Ipp8u* pDst);

Parameters

pSrc	Pointer to the source image row.
pDst	Pointer to the destination image row.
srcWidth	Width of the source row in pixels.

Description

The function ippiSampleDownRowH2V1_Box_JPEG is declared in the ippj.h file. This function performs 2:1 horizontal sampling and 1:1 vertical sampling of an image row. Downsampling is performed as a simple “box” filter.

Example “Using the function ippiSampleDownRowH2V1_Box_JPEG” shows how to use the function ippiSampleDownRowH2V1_Box_JPEG_8u_C1.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error condition if one or both of the specified pointers are NULL.
ippStsSizeErr	Indicates an error condition if srcWidth has a zero or negative value.

Using the function ippiSampleDownRowH2V1_Box_JPEG

void func_sampling()

    Ipp8u pSrc[8*8];

    IppiSize srcSize = {8, 8};

    int srcStep = 8*sizeof(Ipp8u);

    int srcWidth = 8;

    Ipp8u pDst[8*8];

    ippiImageJaehne_8u_C1R( pSrc, srcStep, srcSize);

    for(int r = 0; r < 8; r++)

       ippiSampleDownRowH2V1_Box_JPEG_8u_C1( &pSrc[8*r], srcWidth, &pDst[4*r]);

Result:

            pSrc (8x8)
                               pDst (8x4)

  0   67  165  209  209  165   67    0             34  187  187   33

 67  209  255  250  250  255  209   67            138  252  253  138

165  255  226  188  188  226  255  165            210  207  207  210

209  250  188  140  140  188  250  209            230  164  164  229

209  250  188  140  140  188  250  209            230  164  164  229

165  255  226  188  188  226  255  165            210  207  207  210

 67  209  255  250  250  255  209   67            138  252  253  138

  0   67  165  209  209  165   67    0             34  187  187   33