Threshold_LTValGTVal

Performs double thresholding of pixel values in an image buffer.

Syntax

Case 1: Not-in-place operation on one-channel data

IppStatus ippiThreshold_LTValGTVal_<mod>(const Ipp<datatype>* pSrc, int srcStep, Ipp<datatype>* pDst, int dstStep, IppiSize roiSize, Ipp<datatype> thresholdLT, Ipp<datatype> valueLT, Ipp<datatype> thresholdGT, Ipp<datatype> valueGT);

Supported values for mod:

8u_C1R

16u_C1R

16s_C1R

32f_C1R

Case 2: Not-in-place operation on multi-channel data

IppStatus ippiThreshold_LTValGTVal_<mod>(const Ipp<datatype>* pSrc, int srcStep, Ipp<datatype>* pDst, int dstStep, IppiSize roiSize, const Ipp<datatype> thresholdLT[3], const Ipp<datatype> valueLT[3], const Ipp<datatype> thresholdGT[3], const Ipp<datatype> valueGT[3]);

Supported values for mod:

8u_C3R	16u_C3R	16s_C3R	32f_C3R
8u_AC4R	16u_AC4R	16s_AC4R	32f_AC4R

Case 3: In-place operation on one-channel data

IppStatus ippiThreshold_LTValGTVal_<mod>(Ipp<datatype>* pSrcDst, int srcDstStep, IppiSize roiSize, Ipp<datatype> thresholdLT, Ipp<datatype> valueLT, Ipp<datatype> thresholdGT, Ipp<datatype> valueGT);

Supported values for mod:

8u_C1IR

16u_C1IR

16s_C1IR

32f_C1IR

Case 4: In-place operation on multi-channel data

IppStatus ippiThreshold_LTValGTVal_<mod>(Ipp<datatype>* pSrcDst, int srcDstStep, IppiSize roiSize, const Ipp<datatype> thresholdLT[3], const Ipp<datatype> valueLT[3], const Ipp<datatype> thresholdGT[3], const Ipp<datatype> valueGT[3]);

Supported values for mod

8u_C3IR	16u_C3IR	16s_C3IR	32f_C3IR
8u_AC4IR	16u_AC4IR	16s_AC4IR	32f_AC4IR

Parameters

pSrc	Pointer to the source image ROI.
srcStep	Distance in bytes between starts of consecutive lines in the source image.
pDst	Pointer to the destination image ROI.
dstStep	Distance in bytes between starts of consecutive lines in the destination image.
pSrcDst	Pointer to the source and destination image ROI (for the in-place operation).
srcDstStep	Distance in bytes between starts of consecutive lines in the source and destination image buffer (for the in-place operation).
roiSize	Size of the source and destination ROI in pixels.
thresholdLT	The lower threshold value to use for each pixel.In case of multi-channel data, an array of three lower threshold values (one for each color channel) is used.
valueLT	The lower output value to be set for each pixel that is less than thresholdLT. In case of multi-channel data, an array of 3 lower output values (one for each color channel) is used.
thresholdGT	The upper threshold value to use for each pixel.In case of multi-channel data, an array of three upper threshold values (one for each color channel) is used.
valueGT	The upper output value to be set for each pixel that exceeds thresholdGT. In case of multi-channel data, an array of three upper output values (one for each color channel) is used.

Description

The function ippiThreshold_LTValGTVal is declared in the ippi.h file. It operates with ROI (see Regions of Interest in Intel IPP).

This function thresholds pixels in the source image pSrc using two specified levels thresholdLT and thresholdGT. Pixel values in the source image are compared to these levels. If the pixel value is less than thresholdLT, the corresponding output pixel is set to valueLT. If the pixel value is greater than thresholdGT, the output pixel is set to valueGT. Otherwise, it is set to the source pixel value. The value of thresholdLT should be less than or equal to thresholdGT.

Example “Thresholding an Image” illustrates thresholding with two levels.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or a warning.
ippStsNullPtrErr	Indicates an error condition if one of the specified pointer is NULL.
ippStsSizeErr	Indicates an error condition if roiSize has a field with zero or negative value.
ippStsThresholdErr	Indicates an error when thresholdLT is greater than thresholdGT.
ippStsStepErr	Indicates an error condition if srcStep, dstStep, or srcDstStep has a zero or negative value.

Thresholding an Image

IppStatus threshold( void ) {
   Ipp8u x[5*4];
   IppiSize roi = {5,4};
   int i;

   for( i=0; i<5*4; ++i ) x[i] = (Ipp8u)i;

   return ippiThreshold_LTValGTVal_8u_C1IR( x, 5, roi, 2,1,6,7 );
}

The destination image x contains:

  01 01 02 03 04
  05 06 07 07 07
  07 07 07 07 07
  07 07 07 07 07