HOG
Computes the HOG descriptor.
Syntax
IppStatus ippiHOG_<mod>(const Ipp<srcDatatype>*
pSrc
, int
srcStep
, IppiSize
roiSize
, const IppiPoint*
pLocation
, int
nLocations
, Ipp32f*
pDst
, const IppiHOGSpec*
pHOGSpec
, IppiBorderType
borderID
, Ipp<srcDatatype>
borderValue
, Ipp8u*
pBuffer
);
Supported values for
mod
:8u32f_C1R | 16u32f_C1R | 16s32f_C1R | 32f_C1R |
IppStatus ippiHOG_<mod>(const Ipp<srcDatatype>*
pSrc
, int
srcStep
, IppiSize
roiSize
, const IppiPoint*
pLocation
, int
nLocations
, Ipp32f*
pDst
, const IppiHOGSpec*
pHOGCtx
, IppiBorderType
borderID
, Ipp<srcDatatype>
borderValue
[3], Ipp8u*
pBuffer
);
Supported values for
mod
:8u32f_C3R | 16u32f_C3R | 16s32f_C3R | 32f_C3R |
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 ROI.
- srcStep
- Distance, in bytes, between the starting points of consecutive lines in the source image.
- roiSize
- Size of the source image ROI, in pixels.
- pLocation
- Pointer to the array with detection window locations.
- nLocations
- Number of locations.
- pDst
- Pointer to the HOG descriptor.
- pHOGCtx,pHOGSpec
- Pointer to the HOG context/specification structure.
- borderID
- Type of border. Possible values are:
- ippBorderConst
- Values of all border pixels are set to a constant.
- ippBorderRepl
- Border is replicated from the edge pixels.
- ippBorderInMem
- Border is obtained from the source image pixels in memory.
- ippBorderMirror
- Border pixels are mirrored from the source image boundary pixels.
Mixed borders are also supported. They can be obtained by the bitwise operation OR betweenippBorderReplandippBorderInMemTop,ippBorderInMemBottom,ippBorderInMemLeft,ippBorderInMemRight. - borderValue
- Constant value to assign to pixels of the constant border. This parameter is applicable only to theippBorderConstborder type.
- pBuffer
- Pointer to the work buffer.
Description
This function computes the HOG descriptor over defined locations of the detection window. Flavors with the
C1
suffix operate on one-channel (gray) images, and C3
flavors operate on color images.Before using this function, compute the size of the context structure, work buffer, and descriptor using the HOGGetSize, HOGGetBufferSize, and HOGGetDescriptorSize functions, respectively. To initialize the HOG context structure, use the HOGInit function.
Return Values
- ippStsNoErr
- Indicates no error. Any other value indicates an error or a warning.
- ippStsNullPtrErr
- Indicates an error when one of the specified pointers isNULL.
- ippStsContextmatchErr
- Indicates an error when the context parameter does not match the operation.
- ippStsStepErr
- Indicates an error whensrcStepis less than, or equal to zero.
- ippStsNotEvenStepErr
- Indicates an error whensrcStepis not divisible by input data type size.
- ippStsBorderErr
- Indicates an error whenborderIDhas an illegal value.
- ippStsSizeErr
- Indicates an error whenroiSizeis less than, or equal to zero.
Example
/*******************************************************************************
* Copyright 2015-2021 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 computing HOG descriptor using Intel(R) Integrated Primitives (Intel(R) IPP) functions:
// ippiHOGGetSize
// ippiHOGInit
// ippiHOGGetBufferSize
// ippiHOGGetDescriptorSize
// ippiHOG_8u32f_C1R
#include <stdio.h>
#include "ipp.h"
#define WIND_WIDTH 64 /* detection window width */
#define WIND_HEIGHT 128 /* detection window 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 */
/* Results of ippMalloc() are not validated because Intel(R) IPP functions perform bad arguments check and will return an appropriate status */
static IppiHOGConfig config = { /* HOG configure structure */
1, /* Use OpenCV compatible output format */
8, /* Cell size (pixels) */
16, /* Block size (pixels) */
8, /* Block stride size (pixels) */
9, /* Number of bins (orientations) in the histogram */
1.0f, /* Sigma value (in the applied Gaussian) */
0.2f, /* Threshold value (applied for normalization) */
{WIND_WIDTH, WIND_HEIGHT}, /* Size (width and height in pixels) of detection window */
};
int main(void)
{
IppStatus status = ippStsNoErr;
Ipp8u* pSrc = NULL; /* Pointers to source/destination/feature images */
int srcStep = 0; /* Steps, in bytes, through the source/destination/feature images */
IppiSize roiSize = { WIND_WIDTH, WIND_HEIGHT }; /* Size of source ROI in pixels */
const Ipp8u borderValue = 0;
IppiHOGSpec* pHOGctx = NULL; /* Pointer to the HOG context */
int hogCtxSize = 0, hogBuffSize = 0, winBuffSize = 0; /* Sizes of buffers */
Ipp8u* pBuffer = NULL; /* Pointer to the work buffer */
IppiPoint loc[] = { { 0, 0 }, { 2, 1 }, { 4, 2 }, { 6, 3 } }; /* Locations of detection window */
int numLocs = sizeof(loc) / sizeof(IppiPoint);
Ipp32f* pDescriptor = NULL; /* HOG descriptor */
check_sts( status = ippiHOGGetSize(&config, &hogCtxSize) ) /* Get size of HOG context */
pHOGctx = (IppiHOGSpec*)ippsMalloc_8u(hogCtxSize);
check_sts( status = ippiHOGInit(&config, pHOGctx) ) /* Initialize HOG context */
pSrc = ippiMalloc_8u_C1(roiSize.width, roiSize.height, &srcStep);
/* Compute the temporary work buffer size */
check_sts( status = ippiHOGGetBufferSize(pHOGctx, roiSize, &hogBuffSize) )
pBuffer = ippsMalloc_8u(hogBuffSize);
/* Compute size of HOG descriptor */
check_sts( status = ippiHOGGetDescriptorSize(pHOGctx, &winBuffSize) )
pDescriptor = (Ipp32f*)ippsMalloc_8u(numLocs*winBuffSize);
check_sts( status = ippiHOG_8u32f_C1R(pSrc, srcStep, roiSize, /* Compute HOG descriptor */
loc, numLocs, pDescriptor, pHOGctx, ippBorderConst, borderValue, pBuffer) )
EXIT_MAIN
ippiFree(pSrc);
ippsFree(pHOGctx);
ippsFree(pBuffer);
ippsFree(pDescriptor);
printf("Exit status %d (%s)\n", (int)status, ippGetStatusString(status));
return (int)status;
}