Extracting pixels from an image random

Hello,

How can I extract 100 pixels color randomly from an image ?

Answer 1

[Guillaume]

One way:

row = randi(size(yourimage, 1), 100, 1);  %select 100 row coordinates at random
col = randi(size(yourimage, 1), 100, 1);  %and 100 columns to go with it
rgb = yourimage(sub2ind(size(yourimage), repmat(row, 1, 3), repmat(col, 1, 3), repmat(1:3, 100, 1)));  

%for pretty display
table(row, col, rgb)

[andrei alex]

Thank you .

And if I have 200 images and I want to extract 100 pixels for each?

[Guillaume]

Wrap that in a loop over your 200 images.

Answer 2

[Image Analyst]

Here is another way:

% Load standard demo RGB image:
rgbImage = imread('peppers.png');
% Extract the individual red, green, and blue color channels:
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Get 100 random locations:
locations = randperm(numel(redChannel), 100)
% Get R, G, and B values at those locations:
redValues = redChannel(locations)
greenValues = greenChannel(locations)
blueValues = blueChannel(locations)