Developer Reference

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

EigenValsVecsBorder

Calculates eigen values and eigen vectors of image blocks for corner detection.

Syntax

IppStatus ippiEigenValsVecsBorder_8u32f_C1R(const Ipp8u*
pSrc
, int
srcStep
, Ipp32f*
pEigenVV
, int
eigStep
, IppiSize
roiSize
, IppiKernelType
kernType
, int
apertureSize
, int
avgWindow
, IppiBorderType
borderType
, Ipp8u
borderValue
, Ipp8u*
pBuffer
);
IppStatus ippiEigenValsVecsBorder_32f_C1R(const Ipp32f*
pSrc
, int
srcStep
, Ipp32f*
pEigenVV
, int
eigStep
, IppiSize
roiSize
, IppiKernelType
kernType
, int
apertureSize
, int
avgWindow
, IppiBorderType
borderType
, Ipp32f
borderValue
, Ipp8u*
pBuffer
);
Include Files
ippcv.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 the starting points of consecutive lines in the source image.
pEigenVV
Image to store the results.
eigStep
Distance, in bytes, between the starting points of consecutive lines in the output image.
roiSize
Size of the source image ROI, in pixels.
kernType
Specifies the type of kernel used to compute derivatives, possible values are:
ippKernelSobel
Sobel kernel 3x3 or 5x5
ippKernelSobelNeg
Negative Sobel kernel 3x3 or 5x5
ippKernelScharr
Scharr kernel 3x3
apertureSize
Size of the derivative operator in pixels, possible values are 3 or 5.
border
Type of image border. Possible values:
ippBorderConst
Values of all border pixels are set to a constant.
ippBorderRepl
Border is replicated from the edge pixels.
borderValue
Constant value to assign to pixels of the constant border. This parameter is applicable only to the
ippBorderConst
border type.
avgWindow
Size of the blurring window in pixels, possible values are 3 or 5.
pBuffer
Pointer to the temporary buffer.
Description
This function operates with ROI (see Regions of Interest in Intel IPP).
This function takes a block around the pixel and computes the first derivatives D
x
and D
y
. This operation is performed for every pixel of the image using either Sobel or Scharr kernel in accordance with the
kernType
parameter. The
apertureSize
parameter specifies the size of the Sobel kernel. If this parameter is set to 3, the function used 3x3 kernel, if it is set to 5, the function uses 5x5 kernel. Only 3x3 size is available for the Scharr kernel, therefore the parameter
apertureSize
must be set to 3 if the Scharr kernel is used.
If the parameter
apertureSize
is set to 5 for operation with the Scharr kernel, the function returns error status.
The function computes eigen values and vectors of the following matrix:
The summation is performed over the full block with averaging over the blurring window with size
avgWindow
.
The image
eigenVV
has the following format. For every pixel of the source image it contains six floating-point values -
λ
1,
λ
2 , x1, y1, x2, y2. These values are defined as follows:
λ
1,
λ
2
Eigen values of the above matrix (
λ
1
λ
2
0).
x1, y1
Coordinates of the normalized eigen vector corresponding to
λ
1.
x2, y2
Coordinates of the normalized eigen vector corresponding to
λ
2.
In case of a singular matrix or when one eigen value is much smaller than the second one, all these six values are set to 0.
The function requires a temporary work buffer. Before using this function, compute the size of the buffer using the
ippiEigenValsVecsGetBufferSize
function.
The parameters
apertureSize
and
avgWindow
must be the same for both functions
ippiEigenValsVecsGetBufferSize
and
ippiEigenValsVecsBorder
.
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
pRoiSize
has a field with zero or negative value, or if
apertureSize
or
avgWindow
has an illegal value; or if
kernType
has a wrong value.
ippStsStepErr
Indicates an error condition if
srcStep
is less than
roiSize.width*<pixelSize>
, or
eigStep
is less than
roiSize.width*sizeof(Ipp32f)*6
.
ippStsNotEvenStepErr
Indicates an error condition if steps for floating-point images are not divisible by 4.
ippStsBorderErr
Indicates an error if
borderType
has an illegal value.

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