Extracts Hough lines from a single channel 8-bit binarized (0, 255) source feature (canny edges, etc.) image. More...

Functions
NppStatus	nppiFilterHoughLineGetBufferSize (NppiSize oSizeROI, NppPointPolar nDelta, int nMaxLineCount, int *hpBufferSize)
	Calculate scratch buffer size needed for the FilterHoughLine or FilterHoughLineRegion functions based on destination image SizeROI width and height and nDelta parameters. More...

NppStatus	nppiFilterHoughLine_8u32f_C1R_Ctx (const Npp8u pSrc, int nSrcStep, NppiSize oSizeROI, NppPointPolar nDelta, int nThreshold, NppPointPolar pDeviceLines, int nMaxLineCount, int pDeviceLineCount, Npp8u pDeviceBuffer, NppStreamContext nppStreamCtx)
	1 channel 8-bit unsigned binarized (0, 255) source feature (canny edges, etc.) source image to list of lines in point polar format representing the length (rho) and angle (theta) of each line from the origin of the normal to the line using the formula rho = x cos(theta) + y sin(theta). More...

NppStatus	nppiFilterHoughLine_8u32f_C1R (const Npp8u pSrc, int nSrcStep, NppiSize oSizeROI, NppPointPolar nDelta, int nThreshold, NppPointPolar pDeviceLines, int nMaxLineCount, int pDeviceLineCount, Npp8u pDeviceBuffer)

NppStatus	nppiFilterHoughLineRegion_8u32f_C1R_Ctx (const Npp8u pSrc, int nSrcStep, NppiSize oSizeROI, NppPointPolar nDelta, int nThreshold, NppPointPolar pDeviceLines, NppPointPolar oDstROI[2], int nMaxLineCount, int pDeviceLineCount, Npp8u pDeviceBuffer, NppStreamContext nppStreamCtx)
	1 channel 8-bit unsigned binarized (0, 255) source feature (canny edges, etc.) source image to list of lines in point polar format representing the length (rho) and angle (theta) of each line from the origin of the normal to the line using the formula rho = x cos(theta) + y sin(theta). More...

NppStatus	nppiFilterHoughLineRegion_8u32f_C1R (const Npp8u pSrc, int nSrcStep, NppiSize oSizeROI, NppPointPolar nDelta, int nThreshold, NppPointPolar pDeviceLines, NppPointPolar oDstROI[2], int nMaxLineCount, int pDeviceLineCount, Npp8u pDeviceBuffer)

Detailed Description

Extracts Hough lines from a single channel 8-bit binarized (0, 255) source feature (canny edges, etc.) image.

Outputs a list of lines in point polar format representing the length (rho) and angle (theta) of each line from the origin of the normal to the line using the formula rho = x cos(theta) + y sin(theta). The level of discretization, nDelta, is specified as an input parameter. The performance and effectiveness of this function highly depends on this parameter with higher performance for larger numbers and more detailed results for lower numbers. Also, lines are not guaranteed to be added to the pDeviceLines list in the same order from one call to the next. However, all of the same lines will still be generated as long as nMaxLineCount is set large enough so that they all can fit in the list. To convert lines in point polar format back to cartesian lines use the following formula:

*
*  Npp32f nHough = ((sqrt(2.0F) * static_cast<Npp32f>(oSizeROI.height > oSizeROI.width ? oSizeROI.height 
*                                                                                      : oSizeROI.width)) / 2.0F); 
*  int nAccumulatorsHeight = nDelta.rho > 1.0F ? static_cast<int>(ceil(nHough * 2.0F)) 
*                                              : static_cast<int>(ceil((nHough * 2.0F) / nDelta.rho));
*  int nCenterX = oSizeROI.width >> 1;
*  int nCenterY = oSizeROI.height >> 1;
*  Npp32f nThetaRad = static_cast<Npp32f>(deviceline.theta) * 0.0174532925199433F;
*  Npp32f nSinTheta = sin(nThetaRad);
*  Npp32f nCosTheta = cos(nThetaRad);
*  int nX1, nY1, nX2, nY2;
*
*  if (deviceline.theta >= 45 && deviceline.theta <= 135) // degrees
*  {
*      // y = (rho - x cos(theta)) / sin(theta)
*      nX1 = minimum cartesian X boundary value;
*      nY1 = static_cast<int>((static_cast<Npp32f>(deviceline.rho - (nAccumulatorsHeight >> 1)) - 
*                             ((nX1 - nCenterX) * nCosTheta)) / nSinTheta + nCenterY);
*      nX2 = maximum cartesian X boundary value;
*      nY2 = static_cast<int>((static_cast<Npp32f>(deviceline.rho - (nAccumulatorsHeight >> 1)) - 
*                             ((nX2 - nCenterX) * nCosTheta)) / nSinTheta + nCenterY);
*  }
*  else
*  {
*      // x = (rho - y sin(theta)) / cos(theta)
*      nY1 = minimum cartesian Y boundary value;
*      nX1 = static_cast<int>((static_cast<Npp32f>(deviceline.rho - (nAccumulatorsHeight >> 1)) - 
*                             ((nY1 - nCenterY) * nSinTheta)) / nCosTheta + nCenterX);
*      nY2 = maximum cartesian Y boundary value;
*      nX2 = static_cast<int>((static_cast<Npp32f>(deviceline.rho - (nAccumulatorsHeight >> 1)) - 
*                             ((nY2 - nCenterY) * nSinTheta)) / nCosTheta + nCenterX);
*  }
*  

Function Documentation

NppStatus nppiFilterHoughLine_8u32f_C1R	(	const Npp8u *	pSrc,
		int	nSrcStep,
		NppiSize	oSizeROI,
		NppPointPolar	nDelta,
		int	nThreshold,
		NppPointPolar *	pDeviceLines,
		int	nMaxLineCount,
		int *	pDeviceLineCount,
		Npp8u *	pDeviceBuffer
	)

NppStatus nppiFilterHoughLine_8u32f_C1R_Ctx	(	const Npp8u *	pSrc,
		int	nSrcStep,
		NppiSize	oSizeROI,
		NppPointPolar	nDelta,
		int	nThreshold,
		NppPointPolar *	pDeviceLines,
		int	nMaxLineCount,
		int *	pDeviceLineCount,
		Npp8u *	pDeviceBuffer,
		NppStreamContext	nppStreamCtx
	)

1 channel 8-bit unsigned binarized (0, 255) source feature (canny edges, etc.) source image to list of lines in point polar format representing the length (rho) and angle (theta) of each line from the origin of the normal to the line using the formula rho = x cos(theta) + y sin(theta).

The level of discretization, nDelta, is specified as an input parameter. The performance and effectiveness of this function highly depends on this parameter with higher performance for larger numbers and more detailed results for lower numbers. nDelta must have the same values as those used in the nppiFilterHoughLineGetBufferSize() function call.

Parameters

pSrc	Source-Image Pointer.
nSrcStep	Source-Image Line Step.
oSizeROI	Region-of-Interest (ROI).
nDelta	Discretization steps, range 0.0F < radial increment nDelta.rho < 3.0F, 1.0F recommended, range 0.25F < angular increment nDelta.theta < 3.0F, 1.0F recommended.
nThreshold	Minimum number of points to accept a line.
pDeviceLines	Device pointer to (nMaxLineCount * sizeof(NppPointPolar) line objects.
nMaxLineCount	The maximum number of lines to output.
pDeviceLineCount	The number of lines detected by this function up to nMaxLineCount.
pDeviceBuffer	pointer to scratch DEVICE memory buffer of size hpBufferSize (see nppiFilterHoughLineGetBufferSize() above)
nppStreamCtx	Application Managed Stream Context.

Returns: Image Data Related Error Codes, ROI Related Error Codes

NppStatus nppiFilterHoughLineGetBufferSize	(	NppiSize	oSizeROI,
		NppPointPolar	nDelta,
		int	nMaxLineCount,
		int *	hpBufferSize
	)

Calculate scratch buffer size needed for the FilterHoughLine or FilterHoughLineRegion functions based on destination image SizeROI width and height and nDelta parameters.

Parameters

oSizeROI	Region-of-Interest (ROI).
nDelta	rho radial increment and theta angular increment that will be used in the FilterHoughLine or FilterHoughLineRegion function call.
nMaxLineCount	The maximum number of lines expected from the FilterHoughLine or FilterHoughLineRegion function call.
hpBufferSize	Required buffer size in bytes. Important: hpBufferSize is a host pointer. Scratch Buffer and Host Pointer.

Returns: Image Data Related Error Codes, ROI Related Error Codes

NppStatus nppiFilterHoughLineRegion_8u32f_C1R	(	const Npp8u *	pSrc,
		int	nSrcStep,
		NppiSize	oSizeROI,
		NppPointPolar	nDelta,
		int	nThreshold,
		NppPointPolar *	pDeviceLines,
		NppPointPolar	oDstROI[2],
		int	nMaxLineCount,
		int *	pDeviceLineCount,
		Npp8u *	pDeviceBuffer
	)

NppStatus nppiFilterHoughLineRegion_8u32f_C1R_Ctx	(	const Npp8u *	pSrc,
		int	nSrcStep,
		NppiSize	oSizeROI,
		NppPointPolar	nDelta,
		int	nThreshold,
		NppPointPolar *	pDeviceLines,
		NppPointPolar	oDstROI[2],
		int	nMaxLineCount,
		int *	pDeviceLineCount,
		Npp8u *	pDeviceBuffer,
		NppStreamContext	nppStreamCtx
	)

1 channel 8-bit unsigned binarized (0, 255) source feature (canny edges, etc.) source image to list of lines in point polar format representing the length (rho) and angle (theta) of each line from the origin of the normal to the line using the formula rho = x cos(theta) + y sin(theta).

The level of discretization, nDelta, is specified as an input parameter. The performance and effectiveness of this function highly depends on this parameter with higher performance for larger numbers and more detailed results for lower numbers. nDelta must have the same values as those used in the nppiFilterHoughLineGetBufferSize() function call. The oDstROI region limits are used to limit accepted lines to those that fall within those limits.

Parameters

pSrc	Source-Image Pointer.
nSrcStep	Source-Image Line Step.
oSizeROI	Region-of-Interest (ROI).
nDelta	Discretization steps, range 0.0F < radial increment nDelta.rho < 3.0F, 1.0F recommended, range 0.25F < angular increment nDelta.theta < 3.0F, 1.0F recommended.
nThreshold	Minimum number of points to accept a line.
pDeviceLines	Device pointer to (nMaxLineCount * sizeof(NppPointPolar) line objects.
oDstROI	Region limits with oDstROI[0].rho <= accepted rho <= oDstROI[1].rho and oDstROI[0].theta <= accepted theta <= oDstROI[1].theta.
nMaxLineCount	The maximum number of lines to output.
pDeviceLineCount	The number of lines detected by this function up to nMaxLineCount.
pDeviceBuffer	pointer to scratch DEVICE memory buffer of size hpBufferSize (see nppiFilterHoughLineGetBufferSize() above)
nppStreamCtx	Application Managed Stream Context.

Returns: Image Data Related Error Codes, ROI Related Error Codes

Functions

Detailed Description

Function Documentation