how to find color corrologram of an image?

how to find color corrologram of an image?

Answer 1

[Gautam]

Hello @mano,

The general approach for computing a corrologram of an image involves colour quantizing the image and computing the spatial correlation with other colors at specified distances.

Below in an example that uses K-means clustering for colour quantization and heatmap to visualize the corrologram

img = imread('peppers.png');
img = im2double(img);

% Quantize the image colors using k-means clustering
numColors = 16; % Number of colors to quantize to
imgReshaped = reshape(img, [], 3);
[~, C] = kmeans(imgReshaped, numColors, 'MaxIter', 200);

% Assign each pixel to the nearest cluster center
[~, idx] = min(pdist2(imgReshaped, C), [], 2);
idx = reshape(idx, size(img, 1), size(img, 2));

% Define the distances for the correlogram
distances = [1, 3, 5];

% Compute the correlogram
correlogram = zeros(numColors, numColors, length(distances));
for d = 1:length(distances)
    distance = distances(d);
    for i = 1:numColors
        % Create a binary mask for the current color
        mask = (idx == i);
        
        % Compute spatial correlation with other colors
        for j = 1:numColors
            % Shift the mask by the specified distance
            shiftedMask = circshift(mask, [distance, 0]) | circshift(mask, [0, distance]);
            
            % Compute the correlation
            correlogram(i, j, d) = sum(sum((idx == j) & shiftedMask)) / sum(mask(:));
        end
    end
end

% Display the correlogram
heatmap(rgb2gray(correlogram));
colormap("jet")
colorbar;