Matrix Reductions
=================

.. highlight:: cpp



.. index:: gpu::meanStdDev

gpu::meanStdDev
-------------------
.. cpp:function:: void gpu::meanStdDev(const GpuMat& mtx, Scalar& mean, Scalar& stddev)

    Computes mean value and standard deviation of matrix elements.

    :param mtx: Source matrix. ``CV_8UC1`` matrices are supported for now.

    :param mean: Mean value.

    :param stddev: Standard deviation value.

See also: :c:func:`meanStdDev`.



.. index:: gpu::norm

gpu::norm
-------------
.. cpp:function:: double gpu::norm(const GpuMat& src, int normType=NORM_L2)

    Returns norm of matrix (or of two matrices difference).

    :param src: Source matrix. Any matrices except 64F are supported.

    :param normType: Norm type. ``NORM_L1``, ``NORM_L2`` and ``NORM_INF`` are supported for now.

.. cpp:function:: double gpu::norm(const GpuMat& src, int normType, GpuMat& buf)

    :param src: Source matrix. Any matrices except 64F are supported.

    :param normType: Norm type. ``NORM_L1``, ``NORM_L2`` and ``NORM_INF`` are supported for now.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.

.. cpp:function:: double gpu::norm(const GpuMat& src1, const GpuMat& src2, int normType=NORM_L2)

    :param src1: First source matrix. ``CV_8UC1`` matrices are supported for now.

    :param src2: Second source matrix. Must have the same size and type as ``src1``.

    :param normType: Norm type. ``NORM_L1``, ``NORM_L2`` and ``NORM_INF`` are supported for now.

See also: :c:func:`norm`.



.. index:: gpu::sum

gpu::sum
------------
.. cpp:function:: Scalar gpu::sum(const GpuMat& src)

.. cpp:function:: Scalar gpu::sum(const GpuMat& src, GpuMat& buf)

    Returns sum of matrix elements.

    :param src: Source image of any depth except ``CV_64F``.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.

See also: :c:func:`sum`.



.. index:: gpu::absSum

gpu::absSum
---------------
.. cpp:function:: Scalar gpu::absSum(const GpuMat& src)

.. cpp:function:: Scalar gpu::absSum(const GpuMat& src, GpuMat\& buf)

    Returns sum of matrix elements absolute values.

    :param src: Source image of any depth except ``CV_64F``.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.



.. index:: gpu::sqrSum

gpu::sqrSum
---------------
.. cpp:function:: Scalar gpu::sqrSum(const GpuMat& src)

.. cpp:function:: Scalar gpu::sqrSum(const GpuMat& src, GpuMat\& buf)

    Returns squared sum of matrix elements.

    :param src: Source image of any depth except ``CV_64F``.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.



.. index:: gpu::minMax

gpu::minMax
---------------
.. cpp:function:: void gpu::minMax(const GpuMat& src, double* minVal, double* maxVal=0, const GpuMat& mask=GpuMat())

.. cpp:function:: void gpu::minMax(const GpuMat& src, double* minVal, double* maxVal, const GpuMat& mask, GpuMat& buf)

    Finds global minimum and maximum matrix elements and returns their values.

    :param src: Single-channel source image.

    :param minVal: Pointer to returned minimum value. ``NULL`` if not required.

    :param maxVal: Pointer to returned maximum value. ``NULL`` if not required.

    :param mask: Optional mask to select a sub-matrix.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.

Function doesn't work with ``CV_64F`` images on GPU with compute capability :math:`<` 1.3.

See also: :c:func:`minMaxLoc`.



.. index:: gpu::minMaxLoc

gpu::minMaxLoc
------------------
.. cpp:function:: void gpu::minMaxLoc(const GpuMat& src, double* minVal, double* maxVal=0, Point* minLoc=0, Point* maxLoc=0, const GpuMat& mask=GpuMat())

.. cpp:function:: void gpu::minMaxLoc(const GpuMat& src, double* minVal, double* maxVal, Point* minLoc, Point* maxLoc, const GpuMat& mask, GpuMat& valbuf, GpuMat& locbuf)

    Finds global minimum and maximum matrix elements and returns their values with locations.

    :param src: Single-channel source image.

    :param minVal: Pointer to returned minimum value. ``NULL`` if not required.

    :param maxVal: Pointer to returned maximum value. ``NULL`` if not required.

    :param minValLoc: Pointer to returned minimum location. ``NULL`` if not required.

    :param maxValLoc: Pointer to returned maximum location. ``NULL`` if not required.

    :param mask: Optional mask to select a sub-matrix.

    :param valbuf: Optional values buffer to avoid extra memory allocations. It's resized automatically.

    :param locbuf: Optional locations buffer to avoid extra memory allocations. It's resized automatically.

Function doesn't work with ``CV_64F`` images on GPU with compute capability :math:`<` 1.3.

See also: :c:func:`minMaxLoc`.



.. index:: gpu::countNonZero

gpu::countNonZero
---------------------
.. cpp:function:: int gpu::countNonZero(const GpuMat& src)

.. cpp:function:: int gpu::countNonZero(const GpuMat& src, GpuMat& buf)

    Counts non-zero matrix elements.

    :param src: Single-channel source image.

    :param buf: Optional buffer to avoid extra memory allocations. It's resized automatically.

Function doesn't work with ``CV_64F`` images on GPU with compute capability :math:`<` 1.3.

See also: :c:func:`countNonZero`.