Visible to Intel only — GUID: GUID-773F417E-7167-43FE-85B9-39BECED9A5B1
Visible to Intel only — GUID: GUID-773F417E-7167-43FE-85B9-39BECED9A5B1
WarpPerspectiveLinear
Performs warp perspective transformation of an image using the linear interpolation method.
Syntax
IppStatus ippiWarpPerspectiveLinear_<mod>(const Ipp<datatype>* pSrc, int srcStep, Ipp<datatype> pDst, int dstStep, IppiPoint dstRoiOffset, IppiSize dstRoiSize, const IppiWarpSpec* pSpec, Ipp8u* pBuffer);
Supported values for mod:
8u_C1R |
16u_C1R |
16s_C1R |
32f_C1R |
8u_C3R |
16u_C3R |
16s_C3R |
32f_C3R |
8u_C4R |
16u_C4R |
16s_C4R |
32f_C4R |
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. |
srcStep |
Distance, in bytes, between the starting points of consecutive lines in the source image buffer. |
pDst |
Pointer to the destination image ROI. |
dstStep |
Distance, in bytes, between the starting points of consecutive lines in the destination image buffer. |
dstRoiOffset |
Offset of the destination image ROI with respect to the destination image origin. |
dstRoiSize |
Size of the destination image ROI, in pixels. |
pSpec |
Pointer to the specification structure for the warp operation. |
pBuffer |
Pointer to the work buffer. |
Description
This function transforms the source image pixel coordinates (x, y) according to the following formulas:
x' = (c00*x + c01*y + c02)/ (c20*x + c21*y + c22)
y' = (c10*x + c11*y + c12)/(c20*x + c21*y + c22)
where
x' and y' are the pixel coordinates in the transformed image
cij are the affine transform coefficients passed to the coeffs array during initialization
The ippiWarpPerspectiveLinear function operates with ROI (see Regions of Interest in Intel IPP). The transformed part of the source image is resampled with the linear interpolation method and stored in the destination image ROI. You need to define the destination image ROI origin by the following parameters: the offset of the destination ROI with respect to the destination image origin and the destination image ROI size. The parameter pDst must point to the processed destination image ROI.
If you initialize the warp specification structure using the ippiWarpPerspectiveLinearInit function, you can specify the source image ROI in the following ways:
Set the srcRoi value to ippRectInfinite, which means that the ROI is not specified. In this case, pSrc must point to the processed source image. Pixels that are outside the source image boundaries are computed according to the specified border type.
Set the srcRoi value to the part of the processed source image. In this case, pSrc must point to the processed source image ROI. The operations take place only inside the specified region of interest srcRoi. It means that the destination image pixels mapped to the outer pixels of the specified source image region are not changed.
If you initialize the warp specification structure using the ippiWarpQuadLinearInit function, set the pSrc value to the processed source image. The operations take place only inside the source quadrangle srcQuad that is specified in the ippiWarpQuadLinearInit function.
To specify the algorithm for borders processing, set the borderType and pBorderValue parameters when initializing the IppiWarpSpec structure. The data type of pBorderValue is automatically converted from Ipp64f to the data type of the processed images. The function supports the following algorithms for borders processing:
If the border type is equal to ippBorderRepl, the source image outer pixels are replicated from the edge pixels.
If the border type is equal to ippBorderConst, the outer pixels are set to the constant value specified in pBorderValue.
If the border type is equal to ippBorderTransp or ippBorderInMem, destination image pixels mapped to the outer source image pixels are not changed.
Before using the ippiWarpPerspectiveLinear function, you need to initialize the IppiWarpSpec structure using the ippiWarpPerspectiveLinearInit function and compute the size of the external buffer pBuffer using the ippiWarpGetBufferSize function.
To compute the perspective transform parameters, use the ippiGetPerspectiveQuad, ippiGetPerspectiveBound, and ippiGetPerspectiveTransform functions.
For an example on how to use this functionality, refer to the example provided with the ippiWarpPerspectiveNearest function description.
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when one of the specified pointers is NULL. |
ippStsNoOperation |
Indicates a warning when width or height of the destination image is equal to zero. |
ippStsContextMatchErr |
Indicates an error when context data is invalid. |
ippStsNotSupportedModeErr |
Indicates an error when the requested mode is not supported. |
ippStsSizeErr |
Indicates an error when width or height of the source or destination image ROI is negative. |
ippStsStepErr |
Indicates an error when the step value is not a multiple of data type. |
ippStsOutOfRangeErr |
Indicates an error when the destination image offset point is outside the destination image origin. |
ippStsSizeWrn |
Indicates a warning when the destination image ROI size is more than the destination image origin size. |
ippStsWrongIntersectQuad |
Indicates a warning that no operation is performed if the transformed source image extended with borders has no intersection with the destination image. |