WarpQuadNearestInit

Intel® Integrated Performance Primitives Developer Guide and Reference

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ID 790148

Date 11/07/2023

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WarpQuadNearestInit

Initializes the specification structure for warping an arbitrary quadrangle in the source image to the quadrangle in the destination image with the nearest neighbor interpolation method.

Syntax

IppStatus ippiWarpQuadNearestInit(IppiSize srcSize, const double srcQuad[4][2], IppiSize dstSize, const double dstQuad[4][2], IppiWarpTransformType transform, IppDataType dataType, int numChannels, IppiBorderType borderType, const Ipp64f* pBorderValue, int smoothEdge, IppiWarpSpec* pSpec);

Include Files

ippi.h

Domain Dependencies

Headers: ippcore.h, ippvm.h, ipps.h

Libraries: ippcore.lib, ippvm.lib, ipps.lib

Parameters

srcSize

Size of the source image, in pixels.

srcQuad

Quadrangle in the source image.

dstSize

Size of the destination image, in pixels.

dstQuad

Quadrangle in the destination image.

transform

Type of the warp tranform. Supported values:

ippWarpAffine	Affine warping
ippWarpPerspective	Perspective warping

dataType

Data type of the source and destination images. Supported values: ipp8u, ipp16u, ipp16s, and ipp32f.

numChannels

Number of channels in the image. Supported values: 1, 3, or 4.

borderType

Type of border. Supported values:

ippBorderTransp	Outer pixels are not processed.
ippBorderInMem	Border is obtained from the source image pixels in memory.

pBorderValue

Pointer to the constant value to assign to pixels of the constant border. This parameter is applicable only to the ippBorderConst border type.

smoothEdge

Flag for edge smoothing. Supported values:

0 - transformation without edge smoothing.
1 - transformation with edge smoothing.

pSpec

Pointer to the specification structure.

Description

This function initializes the IppiWarpSpec structure for warping an arbitrary quadrangle in the source image to quadrangle in the destination image with the nearest neighbor interpolation method. To compute the size of the specification structure, use the WarpQuadGetSize function.

Transformation coefficients are computed internally, based on the mapping of the source quadrangle to the specified destination quadrangle dstQuad and transform type transform. In case of affine transform, the function computes the coordinates of the fourth vertex of the destination quadrangle that uniquely depends on the three other vertices. If the computed coordinates are not equal to the corresponding values specified in dstQuad, the function returns the warning message and continues initialization with the computed values.

The first dimension [4] of the array specifying the quadrangle srcQuad[4][2] or dstQuad[4][2] is equal to the number of vertices, and the second dimension [2] contains the x and y coordinates of the vertex.

You can apply the edge smoothing feature only if the source quadrangle entirely lies in the source image.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when: One of the specified pointers is NULL, excepting pBorderValue The value of pBorderValue is NULL when the border type is set to ippBorderConst
ippStsSizeErr	Indicates an error when width or height of the source or destination image is less than, or equal to one.
ippStsDataTypeErr	Indicates an error when dataType has an illegal value.
ippStsWarpTransformErr	Indicates an error when transform has an illegal value.
ippStsQuadErr	Indicates an error when any of the given quadrangles is non-convex or degenerates into a triangle, line, or point.
ippStsWrongIntersectQuad	Indicates a warning that no operation is performed if the transformed source image extended with borders has no intersection with the destination image.
ippStsAffineQuadChanged	Indicates a warning when coordinates of the fourth vertex of dstQuad are changed by the function, if transform is set to ippWarpAffine.
ippStsBorderErr	Indicates an error when borderType has an illegal value.
ippStsNumChannelsErr	Indicates an error when numChannels has an illegal value.

Example

/*******************************************************************************
* Copyright 2015 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 the Spec structure initialization for warping of
// an arbitrary quadrangle in the source image to the quadrangle
// in the destination image using Intel(R) Integrated Primitives (Intel(R) IPP) functions:
//     ippiWarpQuadGetSize
//     ippiWarpQuadLinearInit
//     ippiWarpGetBufferSize
//     ippiWarpPerspectiveLinear_8u_C3R


#include <stdio.h>
#include "ipp.h"

#define WIDTH  640 /* Source image width */
#define HEIGHT 480 /* Destination image width */

/* 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 const double srcQuad[4][2] = /* Vertex coordinates of the quadrangle */
{
    { 0.0, 0.0 },
    { 8.0, 0.0 },
    { 6.0, 8.0 },
    { 2.0, 8.0 } };

static const double dstQuad[4][2] = /* Vertex coordinates of the quadrangle */
{
    { 0.0, 0.0 },
    { 8.0, 0.0 },
    { 6.0, 8.0 },
    { 2.0, 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;
    Ipp8u* pSrc = NULL, *pDst = NULL;  /* Pointers to source/destination images */
    int srcStep = 0, dstStep = 0;      /* Steps, in bytes, through the source/destination images */
    IppiSize srcSize = { WIDTH, HEIGHT }, dstSize = { WIDTH, HEIGHT }; /* Size of source/destination ROI in pixels */
    IppiInterpolationType interpolation = ippLinear;
    IppiBorderType borderType = ippBorderTransp; /* Transparent border : destination image pixels mapped to the outer source image pixels are not changed. */
    int    specSize = 0, bufSize = 0;            /* Size, in bytes, of the specification/temporary buffer structure */
    IppiWarpTransformType warpTransformType = ippWarpPerspective;
    IppiWarpSpec* pSpec = NULL; /* Pointer to the specification structure/work buffer */
    Ipp8u* pBuffer = NULL;
    IppiPoint dstOffset = { 0, 0 }; /* Offset of the destination image ROI with respect to the destination image origin */
    int numChannels = 3;

    pSrc = ippiMalloc_8u_C3(srcSize.width, srcSize.height, &srcStep);
    pDst = ippiMalloc_8u_C3(dstSize.width, dstSize.height, &dstStep);

    /* Spec and init buffer sizes */
    check_sts( status = ippiWarpQuadGetSize(srcSize, srcQuad, dstSize, dstQuad, warpTransformType, ipp8u, interpolation, borderType, &specSize, &bufSize) )

    pSpec = (IppiWarpSpec*)ippsMalloc_8u(specSize);

    /* Filter initialization */
    check_sts( status = ippiWarpQuadLinearInit(srcSize, srcQuad, dstSize, dstQuad, warpTransformType, ipp8u, numChannels, borderType, 0, 0, pSpec) )

    check_sts( status = ippiWarpGetBufferSize(pSpec, dstSize, &bufSize) )

    pBuffer = ippsMalloc_8u(bufSize);
    /* Perform perspective transform of an image */
    check_sts( status = ippiWarpPerspectiveLinear_8u_C3R(pSrc, srcStep, pDst, dstStep, dstOffset, dstSize, pSpec, pBuffer) )

EXIT_MAIN
    ippsFree(pSpec);
    ippsFree(pBuffer);
    ippiFree(pSrc);
    ippiFree(pDst);
    printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status));
    return (int)status;
}

Parent topic: Warp Functions with Prior Initialization

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Intel® Integrated Performance Primitives Developer Guide and Reference

WarpQuadNearestInit

Syntax

Include Files

Domain Dependencies

Parameters

Description

Return Values

Example

See Also