| OpenCV 3.4.1 Open Source Computer Vision

Classes | Functions
Arithm Operations on Matrices
Core functionality » OpenGL interoperability » CUDA-accelerated Computer Vision » Operations on Matrices

## Classes
class | cv::cuda::Convolution
| Base class for convolution (or cross-correlation) operator. : More...
class | cv::cuda::DFT
| Base class for DFT operator as a cv::Algorithm. : More...

## Functions
Ptr< Convolution > | cv::cuda::createConvolution (Size user_block_size=Size())
| Creates implementation for cuda::Convolution . More...
Ptr< DFT > | cv::cuda::createDFT (Size dft_size, int flags)
| Creates implementation for cuda::DFT. More...
void | cv::cuda::dft (InputArray src, OutputArray dst, Size dft_size, int flags=0, Stream &stream=Stream::Null())
| Performs a forward or inverse discrete Fourier transform (1D or 2D) of the floating point matrix. More...
void | cv::cuda::gemm (InputArray src1, InputArray src2, double alpha, InputArray src3, double beta, OutputArray dst, int flags=0, Stream &stream=Stream::Null())
| Performs generalized matrix multiplication. More...
void | cv::cuda::mulAndScaleSpectrums (InputArray src1, InputArray src2, OutputArray dst, int flags, float scale, bool conjB=false, Stream &stream=Stream::Null())
| Performs a per-element multiplication of two Fourier spectrums and scales the result. More...
void | cv::cuda::mulSpectrums (InputArray src1, InputArray src2, OutputArray dst, int flags, bool conjB=false, Stream &stream=Stream::Null())
| Performs a per-element multiplication of two Fourier spectrums. More...

## Detailed Description

## Function Documentation

## § createConvolution()

Ptr<Convolution> cv::cuda::createConvolution | ( | Size | user_block_size = `Size()` | ) |

Creates implementation for cuda::Convolution .

Parameters

  user_block_size | Block size. If you leave default value Size(0,0) then automatic estimation of block size will be used (which is optimized for speed). By varying user_block_size you can reduce memory requirements at the cost of speed.

## § createDFT()

Ptr<DFT> cv::cuda::createDFT | ( | Size | dft_size,
|  | int | flags
| ) |  |

Creates implementation for cuda::DFT.

Parameters

  dft_size | The image size.
  flags | Optional flags: DFT_ROWS transforms each individual row of the source matrix. DFT_SCALE scales the result: divide it by the number of elements in the transform (obtained from dft_size ). DFT_INVERSE inverts DFT. Use for complex-complex cases (real-complex and complex-real cases are always forward and inverse, respectively). DFT_COMPLEX_INPUT Specifies that inputs will be complex with 2 channels. DFT_REAL_OUTPUT specifies the output as real. The source matrix is the result of real-complex transform, so the destination matrix must be real.

## § dft()

void cv::cuda::dft | ( | InputArray | src,
|  | OutputArray | dst,
|  | Size | dft_size,
|  | int | flags = `0`,
|  | Stream & | stream = `Stream::Null()`
| ) |  |

Performs a forward or inverse discrete Fourier transform (1D or 2D) of the floating point matrix.

Parameters

  src | Source matrix (real or complex).
  dst | Destination matrix (real or complex).
  dft_size | Size of a discrete Fourier transform.
  flags | Optional flags: DFT_ROWS transforms each individual row of the source matrix. DFT_SCALE scales the result: divide it by the number of elements in the transform (obtained from dft_size ). DFT_INVERSE inverts DFT. Use for complex-complex cases (real-complex and complex-real cases are always forward and inverse, respectively). DFT_COMPLEX_INPUT Specifies that input is complex input with 2 channels. DFT_REAL_OUTPUT specifies the output as real. The source matrix is the result of real-complex transform, so the destination matrix must be real.
  stream | Stream for the asynchronous version.

Use to handle real matrices ( CV32FC1 ) and complex matrices in the interleaved format ( CV32FC2 ).

The source matrix should be continuous, otherwise reallocation and data copying is performed. The function chooses an operation mode depending on the flags, size, and channel count of the source matrix:

- If the source matrix is complex and the output is not specified as real, the destination matrix is complex and has the dft_size size and CV_32FC2 type. The destination matrix contains a full result of the DFT (forward or inverse).
- If the source matrix is complex and the output is specified as real, the function assumes that its input is the result of the forward transform (see the next item). The destination matrix has the dft_size size and CV_32FC1 type. It contains the result of the inverse DFT.
- If the source matrix is real (its type is CV_32FC1 ), forward DFT is performed. The result of the DFT is packed into complex ( CV_32FC2 ) matrix. So, the width of the destination matrix is dft_size.width / 2 + 1 . But if the source is a single column, the height is reduced instead of the width.

See also
  dft

## § gemm()

void cv::cuda::gemm | ( | InputArray | src1,
|  | InputArray | src2,
|  | double | alpha,
|  | InputArray | src3,
|  | double | beta,
|  | OutputArray | dst,
|  | int | flags = `0`,
|  | Stream & | stream = `Stream::Null()`
| ) |  |

Performs generalized matrix multiplication.

Parameters

  src1 | First multiplied input matrix that should have CV_32FC1 , CV_64FC1 , CV_32FC2 , or CV_64FC2 type.
  src2 | Second multiplied input matrix of the same type as src1 .
  alpha | Weight of the matrix product.
  src3 | Third optional delta matrix added to the matrix product. It should have the same type as src1 and src2 .
  beta | Weight of src3 .
  dst | Destination matrix. It has the proper size and the same type as input matrices.
  flags | Operation flags: GEMM_1_T transpose src1 GEMM_2_T transpose src2 GEMM_3_T transpose src3
  stream | Stream for the asynchronous version.

The function performs generalized matrix multiplication similar to the gemm functions in BLAS level

1. For example, gemm(src1, src2, alpha, src3, beta, dst, GEMM_1_T + GEMM_3_T) corresponds to

   \[\texttt{dst} = \texttt{alpha} \cdot \texttt{src1} ^T \cdot \texttt{src2} + \texttt{beta} \cdot \texttt{src3} ^T\]

Note
  Transposition operation doesn't support CV_64FC2 input type.

See also
  gemm

## § mulAndScaleSpectrums()

void cv::cuda::mulAndScaleSpectrums | ( | InputArray | src1,
|  | InputArray | src2,
|  | OutputArray | dst,
|  | int | flags,
|  | float | scale,
|  | bool | conjB = `false`,
|  | Stream & | stream = `Stream::Null()`
| ) |  |

Performs a per-element multiplication of two Fourier spectrums and scales the result.

Parameters

  src1 | First spectrum.
  src2 | Second spectrum with the same size and type as a .
  dst | Destination spectrum.
  flags | Mock parameter used for CPU/CUDA interfaces similarity, simply add a `0` value.
  scale | Scale constant.
  conjB | Optional flag to specify if the second spectrum needs to be conjugated before the multiplication.
  stream | Stream for the asynchronous version.

Only full (not packed) CV_32FC2 complex spectrums in the interleaved format are supported for now.

See also
  mulSpectrums

## § mulSpectrums()

void cv::cuda::mulSpectrums | ( | InputArray | src1,
|  | InputArray | src2,
|  | OutputArray | dst,
|  | int | flags,
|  | bool | conjB = `false`,
|  | Stream & | stream = `Stream::Null()`
| ) |  |

Performs a per-element multiplication of two Fourier spectrums.

Parameters

  src1 | First spectrum.
  src2 | Second spectrum with the same size and type as a .
  dst | Destination spectrum.
  flags | Mock parameter used for CPU/CUDA interfaces similarity.
  conjB | Optional flag to specify if the second spectrum needs to be conjugated before the multiplication.
  stream | Stream for the asynchronous version.

Only full (not packed) CV_32FC2 complex spectrums in the interleaved format are supported for now.

See also
  mulSpectrums