Getting error in Matlab while try to plot the values from a row of the image

Question

I want to write a code in Matlab. There is a picture of size (258, 320). It is a color picture. I want to show the image using one color channel. Try to plotting the values from a row of the image.

% Color planes
img = imread('fruit.png');
imshow(img);

disp(size(img));

% TODO: Select a color plane, display it, inspect values from a row
img_blue = img(:,:,2);
imshow(img_blue);
plot(img_blue(150,0));

I got this error error: img_blue(_,0): subscripts must be either integers 1 to (2^31)-1 or logicals error: execution exception in main.m

Can anyone please help m to overcome the problem.

question from:https://stackoverflow.com/questions/65894818/getting-error-in-matlab-while-try-to-plot-the-values-from-a-row-of-the-image

Answer 1

Your problem is the fact that you're using the indexing from, I guess, Python (as in between 0 and N-1) while Matlab uses indexes starting from 1.

So if you want to plot the first plane, it will be plot(img_blue(150, 1)); instead of plot(img_blue(150, 0));. Similarly, blue is the third main color, so it will actually be img_blue = img(:, :, 3); instead of img_blue = img(:, :, 2);.