WarpAffine

Performs general affine transform of the source image.

Syntax

Case 1: Operation on pixel-order data

IppStatus ippiWarpAffine_<mod>(const Ipp<datatype>* pSrc, IppiSize srcSize, int srcStep, IppiRect srcRoi, Ipp<datatype>* pDst, int dstStep, IppiRect dstRoi, const double coeffs[2][3], int interpolation);

Supported values for mod:

8u_C1R	16u_C1R	32f_C1R	64f_C1R
8u_C3R	16u_C3R	32f_C3R	64f_C3R
8u_C4R	16u_C4R	32f_C4R	64f_C4R
8u_AC4R	16u_AC4R	32f_AC4R	64f_AC4R

Case 2: Operation on planar-order data

IppStatus ippiWarpAffine_<mod>(const Ipp<datatype>* const pSrc[3], IppiSize srcSize, int srcStep, IppiRect srcRoi, Ipp<datatype>* const pDst[3], int dstStep, IppiRect dstRoi, const double coeffs[2][3], int interpolation);

Supported values for mod:

8u_P3R

16u_P3R

32f_P3R

64f_P3R

IppStatus ippiWarpAffine_<mod>(const Ipp<datatype>* const pSrc[4], IppiSize srcSize, int srcStep, IppiRect srcRoi, Ipp<datatype>* const pDst[4], int dstStep, IppiRect dstRoi, const double coeffs[2][3], int interpolation);

Supported values for mod:

8u_P4R

16u_P4R

32f_P4R

64f_P4R

Parameters

pSrc	Pointer to the source image origin. An array of separate pointers to each plane in case of data in planar format.
srcSize	Size in pixels of the source image.
srcStep	Distance in bytes between starts of consecutive lines in the source image buffer.
srcRoi	Region of interest in the source image (of the IppiRect type).
pDst	Pointer to the destination image origin. An array of separate pointers to each plane in case of data in planar format.
dstStep	Distance in bytes between starts of consecutive lines in the destination image buffer.
dstRoi	Region of interest in the destination image (of the IppiRect type).
coeffs	The affine transform coefficients.
interpolation	Specifies the interpolation mode. Possible values are:
	IPPI_INTER_NN - nearest neighbor interpolation
	IPPI_INTER_LINEAR - linear interpolation
	IPPI_INTER_CUBIC - cubic interpolation
	IPPI_INTER_CUBIC2P_CATMULLROM - Catmull-Rom spline
	the following flag is used additionally to the above modes:
	IPPI_SMOOTH_EDGE - edge smoothing

Description

The function ippiWarpAffine is declared in the ippi.h file. It operates with ROI (see ROI Processing in Geometric Transforms).

This affine warp function transforms the source image pixel coordinates (x,y) according to the following formulas:

x' = c₀₀* x + c₀₁* y + c₀₂

y' = c₁₀* x + c₁₁* y + c₁₂

where x' and y' denote the pixel coordinates in the transformed image, and c_ij are the affine transform coefficients passed in the array coeffs.

The affine warping is a general linear transform which incorporates such elementary transformations as scaling, rotation, translation, stretching, and shearing. It always transforms parallel lines into parallel lines and preserves equal distances between points on a line.

The transformed part of the image is resampled using the interpolation mode specified by the interpolation parameter, and written to the destination image ROI.

Figure “Affine Transform of an Image” gives an example of applying the affine warping function ippiWarpAffine to a sample image.

To compute the affine transform parameters, use the ippiGetAffineQuad, ippiGetAffineBound, and ippiGetAffineTransform functions.

Affine Transform of an Image

Example “Using the function ippiShear” shows how to use the function ippiWarpAffine_32f_C1R.

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 any image dimension has zero or negative value.
ippStsInterpolationErr	Indicates an error condition if interpolation has an illegal value.
ippStsCoeffErr	Indicates an error condition if c₀₀c₁₁ - c₀₁c₁₀ = 0.
ippStsRectErr	Indicates an error condition if width or height of the intersection of the srcRoi and source image is less than or equal to 1.
ippStsWrongIntersectROIErr	Indicates an error condition if srcRoi has no intersection with the source image.
ippStsWrongIntersectQuad	Indicates a warning that no operation is performed if the transformed source ROI has no intersection with the destination ROI.