192 lines
6.7 KiB
ReStructuredText
192 lines
6.7 KiB
ReStructuredText
Matrix Reductions
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=================
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.. highlight:: cpp
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gpu::meanStdDev
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-------------------
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Computes a mean value and a standard deviation of matrix elements.
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.. ocv:function:: void gpu::meanStdDev(const GpuMat& mtx, Scalar& mean, Scalar& stddev)
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.. ocv:function:: void gpu::meanStdDev(const GpuMat& mtx, Scalar& mean, Scalar& stddev, GpuMat& buf)
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:param mtx: Source matrix. ``CV_8UC1`` matrices are supported for now.
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:param mean: Mean value.
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:param stddev: Standard deviation value.
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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.. seealso:: :ocv:func:`meanStdDev`
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gpu::norm
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-------------
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Returns the norm of a matrix (or difference of two matrices).
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.. ocv:function:: double gpu::norm(const GpuMat& src1, int normType=NORM_L2)
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.. ocv:function:: double gpu::norm(const GpuMat& src1, int normType, GpuMat& buf)
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.. ocv:function:: double gpu::norm(const GpuMat& src1, const GpuMat& src2, int normType=NORM_L2)
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:param src1: Source matrix. Any matrices except 64F are supported.
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:param src2: Second source matrix (if any) with the same size and type as ``src1``.
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:param normType: Norm type. ``NORM_L1`` , ``NORM_L2`` , and ``NORM_INF`` are supported for now.
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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.. seealso:: :ocv:func:`norm`
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gpu::sum
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------------
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Returns the sum of matrix elements.
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.. ocv:function:: Scalar gpu::sum(const GpuMat& src)
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.. ocv:function:: Scalar gpu::sum(const GpuMat& src, GpuMat& buf)
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:param src: Source image of any depth except for ``CV_64F`` .
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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.. seealso:: :ocv:func:`sum`
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gpu::absSum
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---------------
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Returns the sum of absolute values for matrix elements.
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.. ocv:function:: Scalar gpu::absSum(const GpuMat& src)
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.. ocv:function:: Scalar gpu::absSum(const GpuMat& src, GpuMat& buf)
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:param src: Source image of any depth except for ``CV_64F`` .
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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gpu::sqrSum
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---------------
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Returns the squared sum of matrix elements.
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.. ocv:function:: Scalar gpu::sqrSum(const GpuMat& src)
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.. ocv:function:: Scalar gpu::sqrSum(const GpuMat& src, GpuMat& buf)
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:param src: Source image of any depth except for ``CV_64F`` .
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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gpu::minMax
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---------------
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Finds global minimum and maximum matrix elements and returns their values.
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.. ocv:function:: void gpu::minMax(const GpuMat& src, double* minVal, double* maxVal=0, const GpuMat& mask=GpuMat())
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.. ocv:function:: void gpu::minMax(const GpuMat& src, double* minVal, double* maxVal, const GpuMat& mask, GpuMat& buf)
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:param src: Single-channel source image.
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:param minVal: Pointer to the returned minimum value. Use ``NULL`` if not required.
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:param maxVal: Pointer to the returned maximum value. Use ``NULL`` if not required.
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:param mask: Optional mask to select a sub-matrix.
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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The function does not work with ``CV_64F`` images on GPUs with the compute capability < 1.3.
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.. seealso:: :ocv:func:`minMaxLoc`
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gpu::minMaxLoc
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------------------
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Finds global minimum and maximum matrix elements and returns their values with locations.
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.. ocv:function:: void gpu::minMaxLoc(const GpuMat& src, double* minVal, double* maxVal=0, Point* minLoc=0, Point* maxLoc=0, const GpuMat& mask=GpuMat())
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.. ocv:function:: void gpu::minMaxLoc(const GpuMat& src, double* minVal, double* maxVal, Point* minLoc, Point* maxLoc, const GpuMat& mask, GpuMat& valbuf, GpuMat& locbuf)
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:param src: Single-channel source image.
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:param minVal: Pointer to the returned minimum value. Use ``NULL`` if not required.
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:param maxVal: Pointer to the returned maximum value. Use ``NULL`` if not required.
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:param minLoc: Pointer to the returned minimum location. Use ``NULL`` if not required.
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:param maxLoc: Pointer to the returned maximum location. Use ``NULL`` if not required.
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:param mask: Optional mask to select a sub-matrix.
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:param valbuf: Optional values buffer to avoid extra memory allocations. It is resized automatically.
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:param locbuf: Optional locations buffer to avoid extra memory allocations. It is resized automatically.
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The function does not work with ``CV_64F`` images on GPU with the compute capability < 1.3.
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.. seealso:: :ocv:func:`minMaxLoc`
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gpu::countNonZero
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---------------------
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Counts non-zero matrix elements.
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.. ocv:function:: int gpu::countNonZero(const GpuMat& src)
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.. ocv:function:: int gpu::countNonZero(const GpuMat& src, GpuMat& buf)
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:param src: Single-channel source image.
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:param buf: Optional buffer to avoid extra memory allocations. It is resized automatically.
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The function does not work with ``CV_64F`` images on GPUs with the compute capability < 1.3.
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.. seealso:: :ocv:func:`countNonZero`
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gpu::reduce
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-----------
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Reduces a matrix to a vector.
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.. ocv:function:: void gpu::reduce(const GpuMat& mtx, GpuMat& vec, int dim, int reduceOp, int dtype = -1, Stream& stream = Stream::Null())
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:param mtx: Source 2D matrix.
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:param vec: Destination vector. Its size and type is defined by ``dim`` and ``dtype`` parameters.
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:param dim: Dimension index along which the matrix is reduced. 0 means that the matrix is reduced to a single row. 1 means that the matrix is reduced to a single column.
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:param reduceOp: Reduction operation that could be one of the following:
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* **CV_REDUCE_SUM** The output is the sum of all rows/columns of the matrix.
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* **CV_REDUCE_AVG** The output is the mean vector of all rows/columns of the matrix.
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* **CV_REDUCE_MAX** The output is the maximum (column/row-wise) of all rows/columns of the matrix.
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* **CV_REDUCE_MIN** The output is the minimum (column/row-wise) of all rows/columns of the matrix.
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:param dtype: When it is negative, the destination vector will have the same type as the source matrix. Otherwise, its type will be ``CV_MAKE_TYPE(CV_MAT_DEPTH(dtype), mtx.channels())`` .
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The function ``reduce`` reduces the matrix to a vector by treating the matrix rows/columns as a set of 1D vectors and performing the specified operation on the vectors until a single row/column is obtained. For example, the function can be used to compute horizontal and vertical projections of a raster image. In case of ``CV_REDUCE_SUM`` and ``CV_REDUCE_AVG`` , the output may have a larger element bit-depth to preserve accuracy. And multi-channel arrays are also supported in these two reduction modes.
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.. seealso:: :ocv:func:`reduce`
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