Filters an image using a second derivative vertical Sobel operator.
Syntax
IppStatus ippiFilterSobelVertSecond_<mod>(const Ipp<srcDatatype>* pSrc, int srcStep, Ipp<dstDatatype>* pDst, int dstStep, IppiSize dstRoiSize, IppiMaskSize mask);
Supported values for mod:
| 8u16s_C1R | 8s16s_C1R | 32f_C1R |
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. |
dstRoiSize |
Size of the source and destination ROI in pixels. |
mask |
Predefined mask of IppiMaskSize type. |
Description
The function ippiFilterSobelVertSecond is declared in the ippi.h file. It operates with ROI (see Regions of Interest in Intel IPP). This function applies a second derivative vertical Sobel operator to an image ROI. The corresponding kernel is the matrix of either 3x3 or 5x5 size with the following values:
1 0 -2 0 1
1 -2 1 4 0 -8 0 4
2 -4 2 or 6 0 -12 0 6
1 -2 1 4 0 -8 0 4
1 0 -2 0 1
The anchor cell is the center cell of the kernel (red). The size of the source image ROI is equal to dstRoiSize, the size of the destination image ROI.
This filter has the effect of both enhancing and smoothing vertical edges of an image.
To ensure valid operation when image boundary pixels are processed, the application should correctly define additional border pixels (see Borders).
Example “Using the Function ippiFilterSobelVertSecond” shows how to use the function ippiFilterSobelVertSecond_8u16s_C1R.
Return Values
ippStsNoErr |
Indicates no error. Any other value indicates an error or a warning. |
ippStsNullPtrErr |
Indicates an error condition if pSrc or pDst is NULL. |
ippStsSizeErr |
Indicates an error condition if dstRoiSize has a field with a zero or negative value. |
ippStsStepErr |
Indicates an error condition if srcStep or dstStep has a zero or negative value. |
ippStsMaskSizeErr |
Indicates an error condition if mask has an illegal value. |
Using the Function ippiFilterSobelVertSecond
Ipp8u pSrc[8*8]={
4, 4, 4, 4, 4, 4, 4, 4,
4, 3, 3, 3, 3, 3, 3, 4,
4, 3, 2, 2, 2, 2, 3, 4,
4, 3, 2, 1, 1, 2, 3, 4,
4, 3, 2, 1, 1, 2, 3, 4,
4, 3, 2, 2, 2, 2, 3, 4,
4, 3, 3, 3, 3, 3, 3, 4,
4, 4, 4, 4, 4, 4, 4, 4
};
Ipp16s pDst[8*8];
IppiSize Roi = { 8, 8 };
ippiFilterSobelVertSecond_8u16s_C1R ( pSrc, 8, pDst, 8*sizeof( Ipp16s ),
Roi, ippMskSize3x3 );
Result:
4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 4 4 3 2 2 2 2 3 4 4 3 2 1 1 2 3 4 4 3 2 1 1 2 3 4 pSrc 4 3 2 2 2 2 3 4 4 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 399 1 0 0 0 0 1 -201 197 2 1 0 0 1 2 -3 -4 1 2 1 1 2 1 -4 -4 0 1 3 3 1 0 -4 pDst -4 0 1 3 3 1 0 -4 -4 1 2 1 1 2 1 -4 -3 2 1 0 0 1 2 197 -201 1 0 -12 75 -300 220 593
for example, on real picture it can looks like this
size 128x128 size 126x126
roi 126x126 roi 126x126
ippMskSize3x3
