Developer Reference

  • 2020
  • 07/15/2020
  • Public Content
Contents

GetPerspectiveTransform

Computes the perspective transform coefficients to map the source ROI to the quadrangle with the specified vertex coordinates.

Syntax

IppStatus ippiGetPerspectiveTransform(IppiRect
srcRoi
, const double
quad
[4][2], double
coeffs
[3][3]
);
Include Files
ippi.h
Domain Dependencies
Headers:
ippcore.h
,
ippvm.h
,
ipps.h
Libraries:
ippcore.lib
,
ippvm.lib
,
ipps.lib
Parameters
srcRoi
Region of interest in the source image (of the
IppiRect
type).
quad
Vertex coordinates of the quadrangle, to which the source ROI is mapped by the perspective transform function.
coeffs
Output array. Contains the target perspective transform coefficients.
Description
This function operates with ROI (see ROI Processing in Geometric Transforms).
This function is used as a support function for . It computes the coefficients
coeffs
that should be used by the function to map the source rectangular ROI to the quadrangle with the given vertex coordinates
quad
.
The first dimension [4] of the array
quad
[4][2] is equal to the number of vertices, and the second dimension [2] means
x
and
y
coordinates of the vertex. Quadrangle vertices have the following meaning:
quad
[0] corresponds to the transformed top-left corner of the source ROI,
quad
[1] corresponds to the transformed top-right corner of the source ROI,
quad
[2] corresponds to the transformed bottom-right corner of the source ROI,
quad
[3] corresponds to the transformed bottom-left corner of the source ROI.
Return Values
ippStsNoErr
Indicates no error. Any other value indicates an error.
ippStsSizeErr
Indicates an error condition if
srcRoi
has a size field with zero or negative value.
ippStsCoeffErr
Indicates an error condition if coefficient values are invalid.
ippStsRectErr
Indicates an error condition if width or height of the
srcRoi
is less than or equal to 1.

Example



    
/******************************************************************************* * Copyright 2015-2020 Intel Corporation. * * This software and the related documents are Intel copyrighted materials, and * your use of them is governed by the express license under which they were * provided to you (License). Unless the License provides otherwise, you may not * use, modify, copy, publish, distribute, disclose or transmit this software or * the related documents without Intel's prior written permission. * * This software and the related documents are provided as is, with no express * or implied warranties, other than those that are expressly stated in the * License. *******************************************************************************/ // A simple example of perspective warping of an image // using Intel(R) Integrated Primitives (Intel(R) IPP) functions: // ippiGetPerspectiveTransform // ippiWarpPerspectiveSize // ippiWarpPerspectiveNearestInit // ippiWarpGetBufferSize // ippiWarpPerspectiveNearest_32f_C1R #include <stdio.h> #include "ipp.h" #define WIDTH 8 /* source image width */ #define HEIGHT 8 /* source image height */ /* Next two defines are created to simplify code reading and understanding */ #define EXIT_MAIN exitLine: /* Label for Exit */ #define check_sts(st) if((st) != ippStsNoErr) goto exitLine; /* Go to Exit if Intel(R) IPP function returned status different from ippStsNoErr */ static Ipp32f pSrc[WIDTH*HEIGHT] =/* Pointers to source images */ { 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 5.f, 5.f, 1.f, 1.f, 1.f, 1.f, 1.f, 5.f, 5.f, 5.f, 5.f, 1.f, 1.f, 1.f, 5.f, 5.f, 5.f, 5.f, 5.f, 5.f, 1.f, 1.f, 5.f, 5.f, 5.f, 5.f, 5.f, 5.f, 1.f, 1.f, 1.f, 5.f, 5.f, 5.f, 5.f, 1.f, 1.f, 1.f, 1.f, 1.f, 5.f, 5.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f, 1.f }; static const double quad[4][2] = /* Vertex coordinates of the quadrangle */ { { 0.0, 0.0 }, { 8.0, 0.0 }, { 6.0, 8.0 }, { 0.0, 8.0 } }; /* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status */ int main(void) { IppStatus status = ippStsNoErr; IppiWarpSpec* pSpec = NULL; /* Pointer to the specification structure for the forward transform */ IppiWarpSpec* pSpecB = NULL; /* Pointer to the specification structure for the backward transform */ IppiSize srcSize = { WIDTH, HEIGHT }; /* Size of source ROI in pixels */ IppiRect srcRoi = { 0, 0, WIDTH, HEIGHT }; /* Region of interest in the source image */ IppiRect dstRoi = { 0, 0, WIDTH, HEIGHT }; /* Region of interest in the destination image */ IppiPoint dstOffset = { 0, 0 }; /* Offset of the destination image ROI with respect to the destination image origin */ IppiPoint dstbOffset = { 0, 0 }; /* Offset of the back destination image ROI with respect to the back destination image origin */ int srcStep = WIDTH * sizeof(Ipp32f), dstStep = srcStep, dstbStep = srcStep; /* Steps, in bytes, through the source/destination/back destination images */ Ipp32f pDst[WIDTH*HEIGHT], pDstB[WIDTH*HEIGHT]; /* Pointers to destination/back destination images */ IppiSize dstSize = {WIDTH, HEIGHT}; /* Size of the destination image */ IppiSize dstbSize = {WIDTH, HEIGHT}; /* Size of the back destination image */ double coeffs[3][3] = {0}; int specSize = 0, initSize = 0, bufSize = 0; /* Buffer sizes for the forward transform */ int specSizeB = 0, initSizeB = 0, bufSizeB = 0; /* Buffer sizes for the backward transform */ Ipp8u* pBuffer = NULL, *pBufferB = NULL; /* Work buffers */ IppiBorderType borderType = ippBorderTransp; IppiWarpDirection direction = ippWarpForward; /* Forward transformation direction */ IppiWarpDirection directionB = ippWarpBackward; /* Backward transformation direction */ check_sts( status = ippiSet_32f_C1R(2, pDst, dstStep, dstSize) ) check_sts( status = ippiSet_32f_C1R(3, pDstB, dstbStep, dstbSize) ) /* Computes perspective transform matrix */ check_sts( status = ippiGetPerspectiveTransform(srcRoi, quad, (double(*)[3])coeffs) ) /* Spec and init buffer sizes for the forward transform*/ check_sts( status = ippiWarpPerspectiveGetSize(srcSize, srcRoi, dstSize, ipp32f, coeffs, ippNearest, direction, borderType, &specSize, &initSize) ) /* Spec and init buffer sizes for the backward transform*/ check_sts( status = ippiWarpPerspectiveGetSize(dstSize, dstRoi, dstbSize, ipp32f, coeffs, ippNearest, directionB, borderType, &specSizeB, &initSizeB) ) pSpec = (IppiWarpSpec*)ippsMalloc_8u(specSize); pSpecB = (IppiWarpSpec*)ippsMalloc_8u(specSizeB); /* Filter initialization for the forward transform */ check_sts( status = ippiWarpPerspectiveNearestInit(srcSize, srcRoi, dstSize, ipp32f, coeffs, direction, 1, borderType, NULL, 0, pSpec) ) /* Filter initialization for the backward transform */ check_sts( status = ippiWarpPerspectiveNearestInit(dstSize, dstRoi, dstbSize, ipp32f, coeffs, directionB, 1, borderType, NULL, 0, pSpecB) ) /* Get work buffer size for the forward transform */ check_sts( status = ippiWarpGetBufferSize(pSpec, dstSize, &bufSize) ) /* Get work buffer size for the backward transform */ check_sts( status = ippiWarpGetBufferSize(pSpecB, dstSize, &bufSizeB) ) pBuffer = ippsMalloc_8u(bufSize); pBufferB = ippsMalloc_8u(bufSizeB); /* Warp perspective processing for the forward transform */ check_sts( status = ippiWarpPerspectiveNearest_32f_C1R(pSrc, srcStep, pDst, dstStep, dstOffset, dstSize, pSpec, pBuffer) ) /* Warp perspective processing for the backward transform */ check_sts( status = ippiWarpPerspectiveNearest_32f_C1R(pDst, dstStep, pDstB, dstbStep, dstbOffset, dstbSize, pSpecB, pBufferB) ) EXIT_MAIN ippsFree(pSpec); ippsFree(pSpecB); ippsFree(pBuffer); ippsFree(pBufferB); printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status)); return (int)status; } /* pDst 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 5.0 5.0 1.0 1.0 1.0 1.0 1.0 1.0 5.0 5.0 1.0 1.0 1.0 1.0 1.0 5.0 5.0 5.0 5.0 1.0 1.0 1.0 5.0 5.0 5.0 5.0 5.0 5.0 1.0 1.0 5.0 5.0 5.0 5.0 5.0 5.0 2.0 1.0 1.0 5.0 5.0 5.0 5.0 1.0 2.0 1.0 1.0 1.0 5.0 5.0 1.0 1.0 2.0 pDstB 1.0 1.0 1.0 1.0 1.0 1.0 1.0 3.0 1.0 1.0 1.0 5.0 5.0 1.0 1.0 3.0 1.0 1.0 5.0 5.0 5.0 5.0 1.0 3.0 1.0 5.0 5.0 5.0 5.0 5.0 5.0 1.0 1.0 5.0 5.0 5.0 5.0 5.0 5.0 2.0 1.0 1.0 5.0 5.0 5.0 5.0 1.0 1.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 */

Product and Performance Information

1

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