Random square sampling for single channel images

For a single-channel image with random square sampling, Not a fixed sub-window，how to generate random squares usingMATLAB, an example is as follows，Thank you

Answer 1

[Subhadeep Koley]

Hi, here is one working example.

Hope this helps!

% Read the original image
img = imread('cameraman.tif');
[row, col, ~] = size(img);
imgSize = [row, col];

% Specify dimension of the random square
squareSize = [50, 50];

% Calculate crop rectangle
maximumPosValue = (imgSize - squareSize + 1);
initialRandomPos = [randi(maximumPosValue(1)), randi(maximumPosValue(2))];
cropRect = [initialRandomPos(2), initialRandomPos(1), squareSize(2)-1, squareSize(1)-1];

% Crop the image
imgCropped = imcrop(img, cropRect);

% Visualize results
out = imtile({img, imgCropped}, 'BackgroundColor', 'w');
figure
imshow(out)
title('Original image  |  Random cropped image');

[len Bruce]

Very good, but your square sampling is a set fixed window size, what I want is to generate a square area based on the coordinates of the image formed by random numbers,the sampled square area appears randomly in the image and square size is variable,such as image(x1:x2, y1:y2)

[Subhadeep Koley]

@len Bruce you can randomize the sqare window size like below.

% Read the original image
img = imread('peppers.png');
[row, col, ~] = size(img);
imgSize = [row, col];

% Specify dimension of the random square
val = randi(min(imgSize));
squareSize = [val, val];

% Calculate crop rectangle
maximumPosValue = (imgSize - squareSize + 1);
initialRandomPos = [randi(maximumPosValue(1)), randi(maximumPosValue(2))];
cropRect = [initialRandomPos(2), initialRandomPos(1), squareSize(2)-1, squareSize(1)-1];

% Crop the image
imgCropped = imcrop(img, cropRect);

% Visualize results
out = imtile({img, imgCropped}, 'BackgroundColor', 'w');
figure
imshow(out)
title('Original image  |  Random cropped image');

Answer 2

[len Bruce]

Generate the coordinates of the image square sampling based on random numbers，such as the upper left and the lower right co-ordinates of the ith random sub-window is denoted by （x1,y1）and (x2,y2)respectively. (image(x1:x2, y1:y2))