Color space processing

cuda::cvtColor

Converts an image from one color space to another.

C++: void cuda::cvtColor(InputArray src, OutputArray dst, int code, int dcn=0, Stream& stream=Stream::Null())

Parameters:

• src – Source image with CV_8U , CV_16U , or CV_32F depth and 1, 3, or 4 channels.
• dst – Destination image.
• code – Color space conversion code. For details, see cvtColor() .
• dcn – Number of channels in the destination image. If the parameter is 0, the number of the channels is derived automatically from src and the code .
• stream – Stream for the asynchronous version.

3-channel color spaces (like HSV, XYZ, and so on) can be stored in a 4-channel image for better performance.

See also

cvtColor()

cuda::demosaicing

Converts an image from Bayer pattern to RGB or grayscale.

C++: void cuda::demosaicing(InputArray src, OutputArray dst, int code, int dcn=-1, Stream& stream=Stream::Null())

Parameters:

• src – Source image (8-bit or 16-bit single channel).
• dst – Destination image.
• code – Color space conversion code (see the description below).
• dcn – Number of channels in the destination image. If the parameter is 0, the number of the channels is derived automatically from src and the code .
• stream – Stream for the asynchronous version.

The function can do the following transformations:

• Demosaicing using bilinear interpolation

  • COLOR_BayerBG2GRAY , COLOR_BayerGB2GRAY , COLOR_BayerRG2GRAY , COLOR_BayerGR2GRAY
  • COLOR_BayerBG2BGR , COLOR_BayerGB2BGR , COLOR_BayerRG2BGR , COLOR_BayerGR2BGR

• Demosaicing using Malvar-He-Cutler algorithm ([MHT2011])

  • COLOR_BayerBG2GRAY_MHT , COLOR_BayerGB2GRAY_MHT , COLOR_BayerRG2GRAY_MHT , COLOR_BayerGR2GRAY_MHT
  • COLOR_BayerBG2BGR_MHT , COLOR_BayerGB2BGR_MHT , COLOR_BayerRG2BGR_MHT , COLOR_BayerGR2BGR_MHT

See also

cvtColor()

cuda::swapChannels

Exchanges the color channels of an image in-place.

C++: void cuda::swapChannels(InputOutputArray image, const int dstOrder[4], Stream& stream=Stream::Null())

Parameters:

• image – Source image. Supports only CV_8UC4 type.
• dstOrder – Integer array describing how channel values are permutated. The n-th entry of the array contains the number of the channel that is stored in the n-th channel of the output image. E.g. Given an RGBA image, aDstOrder = [3,2,1,0] converts this to ABGR channel order.
• stream – Stream for the asynchronous version.

The methods support arbitrary permutations of the original channels, including replication.

cuda::gammaCorrection

Routines for correcting image color gamma.

C++: void cuda::gammaCorrection(InputArray src, OutputArray dst, bool forward=true, Stream& stream=Stream::Null())

Parameters:

• src – Source image (3- or 4-channel 8 bit).
• dst – Destination image.
• forward – true for forward gamma correction or false for inverse gamma correction.
• stream – Stream for the asynchronous version.

cuda::alphaComp

Composites two images using alpha opacity values contained in each image.

C++: void cuda::alphaComp(InputArray img1, InputArray img2, OutputArray dst, int alpha_op, Stream& stream=Stream::Null())

Parameters:

• img1 – First image. Supports CV_8UC4 , CV_16UC4 , CV_32SC4 and CV_32FC4 types.
• img2 – Second image. Must have the same size and the same type as img1 .
• dst – Destination image.
• alpha_op –

  Flag specifying the alpha-blending operation:

  • ALPHA_OVER
  • ALPHA_IN
  • ALPHA_OUT
  • ALPHA_ATOP
  • ALPHA_XOR
  • ALPHA_PLUS
  • ALPHA_OVER_PREMUL
  • ALPHA_IN_PREMUL
  • ALPHA_OUT_PREMUL
  • ALPHA_ATOP_PREMUL
  • ALPHA_XOR_PREMUL
  • ALPHA_PLUS_PREMUL
  • ALPHA_PREMUL
• stream – Stream for the asynchronous version.

Note

• An example demonstrating the use of alphaComp can be found at opencv_source_code/samples/gpu/alpha_comp.cpp

[MHT2011]

Pascal Getreuer, Malvar-He-Cutler Linear Image Demosaicking, Image Processing On Line, 2011