Notes

img = imread('peppers.png');

% Reshape the image to a 2D array where each row is a pixel and each column is a color channel
reshaped_img = reshape(img, [], 3);

% Unique rows in the reshaped image
unique_colors = unique(reshaped_img, 'rows');

% Number of distinct colors
n = size(unique_colors, 1);

% Print
fprintf('The number of distinct colors in the image is: %dn', n);

% Calculate the number of colors to reduce to (half of the original distinct colors)
num_colors = round(n / 2);

% Minimum variance quantization
[quantized_img, cmap] = rgb2ind(img, num_colors);

% Convert the indexed image back to RGB using the colormap
quantized_rgb = ind2rgb(quantized_img, cmap);

% Save the quantized image
imwrite(quantized_rgb, 'peppers_quantized.bmp');

% Display the input and quantized images side-by-side
figure;
subplot(1, 2, 1);
imshow(img);
title('Original Image');

subplot(1, 2, 2);
imshow(quantized_rgb);
title('Quantized Image');