Histogram Calculation

cuda::calcHist

Calculates histogram for one channel 8-bit image.

C++: void cuda::calcHist(InputArray src, OutputArray hist, Stream& stream=Stream::Null())

Parameters:

• src – Source image with CV_8UC1 type.
• hist – Destination histogram with one row, 256 columns, and the CV_32SC1 type.
• stream – Stream for the asynchronous version.

cuda::equalizeHist

Equalizes the histogram of a grayscale image.

C++: void cuda::equalizeHist(InputArray src, OutputArray dst, Stream& stream=Stream::Null())

C++: void cuda::equalizeHist(InputArray src, OutputArray dst, InputOutputArray buf, Stream& stream=Stream::Null())

Parameters:

• src – Source image with CV_8UC1 type.
• dst – Destination image.
• buf – Optional buffer to avoid extra memory allocations (for many calls with the same sizes).
• stream – Stream for the asynchronous version.

See also

equalizeHist()

cuda::CLAHE

class cuda::CLAHE : public cv::CLAHE

Base class for Contrast Limited Adaptive Histogram Equalization.

class CV_EXPORTS CLAHE : public cv::CLAHE
{
public:
    using cv::CLAHE::apply;
    virtual void apply(InputArray src, OutputArray dst, Stream& stream) = 0;
};

cuda::CLAHE::apply

Equalizes the histogram of a grayscale image using Contrast Limited Adaptive Histogram Equalization.

C++: void cuda::CLAHE::apply(InputArray src, OutputArray dst)

C++: void cuda::CLAHE::apply(InputArray src, OutputArray dst, Stream& stream)

Parameters:

• src – Source image with CV_8UC1 type.
• dst – Destination image.
• stream – Stream for the asynchronous version.

cuda::createCLAHE

Creates implementation for cuda::CLAHE .

C++: Ptr<cuda::CLAHE> createCLAHE(double clipLimit=40.0, Size tileGridSize=Size(8, 8))

Parameters:

• clipLimit – Threshold for contrast limiting.
• tileGridSize – Size of grid for histogram equalization. Input image will be divided into equally sized rectangular tiles. tileGridSize defines the number of tiles in row and column.

cuda::evenLevels

Computes levels with even distribution.

C++: void cuda::evenLevels(OutputArray levels, int nLevels, int lowerLevel, int upperLevel)

Parameters:

• levels – Destination array. levels has 1 row, nLevels columns, and the CV_32SC1 type.
• nLevels – Number of computed levels. nLevels must be at least 2.
• lowerLevel – Lower boundary value of the lowest level.
• upperLevel – Upper boundary value of the greatest level.

cuda::histEven

Calculates a histogram with evenly distributed bins.

C++: void cuda::histEven(InputArray src, OutputArray hist, int histSize, int lowerLevel, int upperLevel, Stream& stream=Stream::Null())

C++: void cuda::histEven(InputArray src, OutputArray hist, InputOutputArray buf, int histSize, int lowerLevel, int upperLevel, Stream& stream=Stream::Null())

C++: void cuda::histEven(InputArray src, GpuMat hist[4], int histSize[4], int lowerLevel[4], int upperLevel[4], Stream& stream=Stream::Null())

C++: void cuda::histEven(InputArray src, GpuMat hist[4], InputOutputArray buf, int histSize[4], int lowerLevel[4], int upperLevel[4], Stream& stream=Stream::Null())

Parameters:

• src – Source image. CV_8U, CV_16U, or CV_16S depth and 1 or 4 channels are supported. For a four-channel image, all channels are processed separately.
• hist – Destination histogram with one row, histSize columns, and the CV_32S type.
• histSize – Size of the histogram.
• lowerLevel – Lower boundary of lowest-level bin.
• upperLevel – Upper boundary of highest-level bin.
• buf – Optional buffer to avoid extra memory allocations (for many calls with the same sizes).
• stream – Stream for the asynchronous version.

cuda::histRange

Calculates a histogram with bins determined by the levels array.

C++: void cuda::histRange(InputArray src, OutputArray hist, InputArray levels, Stream& stream=Stream::Null())

C++: void cuda::histRange(InputArray src, OutputArray hist, InputArray levels, InputOutputArray buf, Stream& stream=Stream::Null())

C++: void cuda::histRange(InputArray src, GpuMat hist[4], const GpuMat levels[4], Stream& stream=Stream::Null())

C++: void cuda::histRange(InputArray src, GpuMat hist[4], const GpuMat levels[4], InputOutputArray buf, Stream& stream=Stream::Null())

Parameters:

• src – Source image. CV_8U , CV_16U , or CV_16S depth and 1 or 4 channels are supported. For a four-channel image, all channels are processed separately.
• hist – Destination histogram with one row, (levels.cols-1) columns, and the CV_32SC1 type.
• levels – Number of levels in the histogram.
• buf – Optional buffer to avoid extra memory allocations (for many calls with the same sizes).
• stream – Stream for the asynchronous version.