MATLAB contains demosaic() function to convert Bayer pattern encoded image to true color, does it contain opposite function as well?

I am writing a VHDL entity that processes Bayer pattern image to generate a true color image. It would make things easier if MATLAB has a method to generate Bayer pattern encoded image from a given RGB image. I can then use it inside my testbench. How can this be achieved?

Answer 1

[Image Analyst]

No - it would be in the "See also" section if there were. However, you can easily make one simply by interleaving your data in the required pattern.

% Read in sample image.
rgbImage = imread('peppers.png');
% Display the image.
subplot(2,1,1);
imshow(rgbImage);
title('Original RGB image', 'FontSize', 20);

% Create mosaiced image.
[rows, columns, numberOfColorChannels] = size(rgbImage)
mosaicedImage = zeros(rows, columns, 'uint8');
for col = 1 : columns
  for row = 1 : rows
    if mod(col, 2) == 0 && mod(row, 2) == 0
      % Pick red value.
      mosaicedImage(row, col) = rgbImage(row, col, 1);
    elseif mod(col, 2) == 0 && mod(row, 2) == 1
      % Pick green value.
      mosaicedImage(row, col) = rgbImage(row, col, 2);
    elseif mod(col, 2) == 1 && mod(row, 2) == 0
      % Pick green value.
      mosaicedImage(row, col) = rgbImage(row, col, 2);
    elseif mod(col, 2) == 1 && mod(row, 2) == 1
      % Pick blue value.
      mosaicedImage(row, col) = rgbImage(row, col, 3);
    end
  end
end
subplot(2,1,2);
imshow(mosaicedImage);
title('Mosaiced image', 'FontSize', 20);

[Setsuna Yuuki.]

Muchas gracias por la ayuda, me sirvió mucho esta respuesta :D

Answer 2

[Joseph Majdi]

It's probably easiest to use index notation to "subsample" the RGB in every 2nd by 2nd pixel into that sub-color, ie:

originalRGB = imread('peppers.png');
pepperMosaic = zeros(size(originalRGB,[1 2]),'uint8');

pepperMosaic(1:2:end,1:2:end) = originalRGB(1:2:end,1:2:end,2);%Green Pixels (1 of 2)
pepperMosaic(2:2:end,2:2:end) = originalRGB(2:2:end,2:2:end,2);%Green Pixels (2 of 2)
pepperMosaic(2:2:end,1:2:end) = originalRGB(2:2:end,1:2:end,1);%Red Pixels
pepperMosaic(1:2:end,2:2:end) = originalRGB(1:2:end,2:2:end,3);%Blue Pixels

figure; imagesc(originalRGB); title('Original Peppers'); axis equal tight; colormap gray

figure; imagesc(pepperMosaic); title('Peppers Bayer GBRG'); axis equal tight; colormap gray

figure; imagesc(demosaic(pepperMosaic,'gbrg')); title('Reconstructed Peppers from Mosaic'); axis equal tight;

This assumes you want the GBRG mosaic pattern, and you can adjust the indices for GRBG, BGGR, or RGGB (the other bayer formats matlab recognizes in the demosaic function).