boofcv.alg.feature.dense

Class DescribeDenseHogFastAlg<Input extends boofcv.struct.image.ImageBase>

java.lang.Object

boofcv.alg.feature.dense.BaseDenseHog<Input>

boofcv.alg.feature.dense.DescribeDenseHogFastAlg<Input>

public class DescribeDenseHogFastAlg<Input extends boofcv.struct.image.ImageBase>
extends BaseDenseHog<Input>

A variant on the original Histogram of Oriented Gradients (HOG) [1] in which spatial Gaussian weighting has been omitted, allowing for cell histograms to be computed only once. This results in about a two times speed up.

For a description of standard HOG see DescribeImageDenseHoG. Difference from standard HOG

• No gaussian spatial weighting for each pixel inside a block
• No bilinear interpolation between cell centers

[1] Dalal, Navneet, and Bill Triggs. "Histograms of oriented gradients for human detection." Computer Vision and Pattern Recognition, 2005. CVPR 2005.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DescribeDenseHogFastAlg.Cell

Field Summary

Fields inherited from class boofcv.alg.feature.dense.BaseDenseHog

derivX, derivY

Constructor Summary

Constructors

Constructor and Description
DescribeDenseHogFastAlg(int orientationBins, int pixelsPerCell, int cellsPerBlockX, int cellsPerBlockY, int stepBlock, boofcv.struct.image.ImageType<Input> imageType) Configures HOG descriptor computation

Method Summary

Modifier and Type	Method and Description
DescribeDenseHogFastAlg.Cell	getCell(int row, int col)
int	getCellCols()
int	getCellRows()
void	getDescriptorsInRegion(int pixelX0, int pixelY0, int pixelX1, int pixelY1, java.util.List<TupleDesc_F64> output) Convenience function which returns a list of all the descriptors computed inside the specified region in the image
void	process() Computes the descriptor across the input image

Methods inherited from class boofcv.alg.feature.dense.BaseDenseHog

_getDerivX, _getDerivY, createDescription, getCellsPerBlockX, getCellsPerBlockY, getDescriptions, getImageType, getLocations, getOrientationBins, getPixelsPerCell, getRegionWidthPixelX, getRegionWidthPixelY, getStepBlock, setInput

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DescribeDenseHogFastAlg

public DescribeDenseHogFastAlg(int orientationBins,
                               int pixelsPerCell,
                               int cellsPerBlockX,
                               int cellsPerBlockY,
                               int stepBlock,
                               boofcv.struct.image.ImageType<Input> imageType)

Configures HOG descriptor computation

Parameters:

orientationBins - Number of bins in a cell's histogram. 9 recommended

pixelsPerCell - Number of pixel's wide a cell is. 8 recommended

cellsPerBlockX - Number of cells's wide a block is. 3 recommended

cellsPerBlockY - Number of cells's wide a block is. 3 recommended

stepBlock - Number of cells which are skipped between each block

Method Detail

process

public void process()

Computes the descriptor across the input image

Specified by:

process in class BaseDenseHog<Input extends boofcv.struct.image.ImageBase>

getDescriptorsInRegion

public void getDescriptorsInRegion(int pixelX0,
                                   int pixelY0,
                                   int pixelX1,
                                   int pixelY1,
                                   java.util.List<TupleDesc_F64> output)

Convenience function which returns a list of all the descriptors computed inside the specified region in the image

Parameters:

pixelX0 - Pixel coordinate X-axis lower extent

pixelY0 - Pixel coordinate Y-axis lower extent

pixelX1 - Pixel coordinate X-axis upper extent

pixelY1 - Pixel coordinate Y-axis upper extent

output - List of descriptions

getCellRows

public int getCellRows()

getCellCols

public int getCellCols()

getCell

public DescribeDenseHogFastAlg.Cell getCell(int row,
                                            int col)