WarpBilinear

Syntax

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 bilinear transform coefficients.
interpolation	Specifies the interpolation mode. Use one of the following values: IPPI_INTER_NN nearest neighbor interpolation IPPI_INTER_LINEAR linear interpolation IPPI_INTER_CUBIC cubic interpolation IPPI_SMOOTH_EDGE use edge smoothing in addition to one of the above modes.

Description

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

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

x' = c₀₀* x*y + c₀₁* x + c₀₂* y + c₀₃

y' = c₁₀* x*y + c₁₁* x + c₁₂* y + c₁₃

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

The bilinear transform preserves equal distances between points on a line.

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

Figure “Bilinear Transform of an Image” gives an example of applying the bilinear warping function ippiWarpBilinear to a sample image.

To estimate how the source image ROI will be transformed by the ippiWarpBilinear function, use functions ippiWarpBilinearQuad and ippiGetBilinearBound. To calculate coefficients of the bilinear transform which maps source ROI to a given quadrangle, use ippiGetBilinearTransform function.

Example “Using Intel IPP Functions for Bilinear Transform” shows how to use the function ippiWarpBilinear_32f_C1R.

Return Values

ippStsNoErr	Indicates no error.
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.
ippStsStepErr	Indicates an error condition if srcStep or dstStep has a zero or negative value.
ippStsInterpolationErr	Indicates an error condition if interpolation has an illegal value.
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.
ippStsCoeffErr	Indicates an error condition if coefficient values are invalid.
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.