FilterSobelHorizBorder

Filters an image using a horizontal Sobel filter.

Syntax

IppStatus ippiFilterSobelHorizBorder_<mod>(const Ipp<srcDatatype>* pSrc, int srcStep, Ipp<dstDatatype>* pDst, int dstStep, IppiSize dstRoiSize, IppiMaskSize mask, IppiBorderType borderType, Ipp<srcDatatype> borderValue, Ipp8u* pBuffer);

Supported values for mod:

8u16s_C1R

16s_C1R

32f_C1R

IppStatus ippiFilterSobelHorizBorder_<mod>_T(const Ipp<srcDatatype>* pSrc, int srcStep, Ipp<dstDatatype>* pDst, int dstStep, IppiSize dstRoiSize, IppiMaskSize mask, IppiBorderType borderType, Ipp<srcDatatype> borderValue, Ipp8u* pBuffer);

Supported values for mod:

8u16s_C1R_T

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.

srcStep

Distance, in bytes, between the starting points of consecutive lines in the source image.

pDst

Pointer to the destination image ROI.

dstStep

Distance, in bytes, between the starting points of consecutive lines in the destination image.

dstRoiSize

Size of the source and destination ROI in pixels.

mask

Predefined mask of IppiMaskSize. Possible values are ippMskSize3x3 or ippMskSize5x5.

borderType

Type of border. Possible values are:

ippBorderConst	Values of all border pixels are set to constant.
ippBorderRepl	Border is replicated from the edge pixels.
ippBorderMirror	Mirrored border is used.
ippBorderMirrorR	Mirrored border with replication is used.
ippBorderInMem	Border is obtained from the source image pixels in memory.

Mixed borders are also supported. They can be obtained by the bitwise operation OR between any of the ippBorderRepl, ippBorderConst, ippBorderMirror, or ippBorderMirrorR values and the ippBorderInMemTop, ippBorderInMemBottom, ippBorderInMemLeft, ippBorderInMemRight values.

borderValue

Constant value to assign to pixels of the constant border. This parameter is applicable only to the ippBorderConst border type.

pBuffer

Pointer to the work buffer.

Description

Before using this function, you need to compute the size of the work buffer pBuffer using the FilterSobelHorizBorderGetBufferSize function.

This function operates with ROI.

This function applies a horizontal Sobel filter to the pSrc source image ROI. The size of the source image ROI is equal to the destination image ROI size dstRoiSize. The values of border pixels are assigned in accordance with the borderType and borderValue parameters. The kernel of the filter is a matrix of 3x3 or 5x5 size depending on the mask value. The kernels have the following values:

                              1   4   6   4   1

   1   2   1                  2   8   12  8   2

   0   0   0       or         0   0   0   0   0

  -1  -2  -1                 -2  -8  -12  -8  -2

                             -1  -4   -6  -4  -1

The anchor cell is the center cell of the kernel, highlighted in red.

This filter enhances horizontal edges of an image.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when one of the specified pointers is NULL.
ippStsSizeErr	Indicates an error when dstRoiSize is negative, or equal to zero.
ippStsStepErr	Indicates an error when srcStep or dstStep is negative, or equal to zero.
ippStsNotEvenStepErr	Indicates an error when one of the step values is not divisible by 4 for floating-point images, or by 2 for short-integer images.
ippStsBorderErr	Indicates an error when borderType has an illegal value.

Example

The code example below demonstrates how to use the ippiFilterSobelHorizBorderGetBufferSize and ippiFilterSobelHorizBorder_8u16s_C1R functions to filter an image with the Sobel horizontal kernel.

IppStatus fix_sobelhoriz_8u16( void ) {
    Ipp8u pSrc[9*8] =
	    {
	        0, 1, 2, 120, 121, 122, 50, 51, 52,
	        1, 2, 3, 121, 122, 123, 52, 52, 53,
	        3, 4, 5, 130, 131, 132, 63, 64, 65,
	        4, 5, 6, 131, 132, 133, 64, 65, 66,
	        5, 6, 7, 132, 133, 134, 65, 66, 67,
                  8, 7, 6, 134, 133, 132, 67, 66, 65,
                  7, 6, 5, 133, 132, 131, 66, 65, 64,
                  6, 5, 4, 132, 131, 130, 65, 64, 63
          };
    Ipp16s  pDst[8*7];
    Ipp8u   *pBuffer;
    IppiSize roiSize = {8, 7};
    IppiBorderType borderType = ippBorderRepl | ippBorderInMemTop | ippBorderInMemRight;
    int    srcStep = 9 * sizeof(Ipp8u);
    int    dstStep = 8 * sizeof(Ipp16s);
    int    bufferSize;
    IppStatus status;
    ippiFilterSobelHorizBorderGetBufferSize(roiSize, ippMskSize3x3, ipp8u, ipp16s, 1, &bufferSize);
    pBuffer = ippsMalloc_8u(bufferSize);
    status = ippiFilterSobelHorizBorder_8u16s_C1R(pSrc + srcStep, srcStep, pDst, dstStep, roiSize, ippMskSize3x3,
             borderType, 0, pBuffer);
    ippsFree(pBuffer);
    return status;
}

The result is as follows:

pDst -->
 12  12  19  33  40  43  49  52 
 12  12  19  33  40  42  47  51 
  8   8   8   8   8   8   8   8 
 14   8   5   7   4   2   6   4 
  6   0  -3  -1  -4  -6  -2  -4 
 -8  -8  -8  -8  -8  -8  -8  -8 
 -4  -4  -4  -4  -4  -4  -4  -4