Creating a cross pattern in a 128 x 128 matrix in MATLAB

I am trying get get a head start on courses and I've run into a sample problem in my textbook about creating a 128 x 128 of zeros and then filling in a cross pattern of ones in the center of this matrix. I am trying to minimize use of forloops

I was thinking of concatenating matrices, but I am a MATLAB newbie it would also be annoying to designate which positions need to be filled and what not if I concatenate

I am wondering if there is a rectangle function that I can use to create a horizontal and vertical rectangle to make the cross pattern or any other suggestions

Also, is there a way to zoom out on the output....as it is very hard to check a 128 x 128 matrix??? (since the output is broken up into rows and columns)

Thank you very much

Answer 1

[Image Analyst]

Do you mean like this:

workspace;
m = zeros(100)
row1 = 45;
row2 = 54;
m(row1:row2,:) = 255;
m(:,row1:row2) = 255;
image(m);

You can use the variable inspector to look at the values, just double click on the variable name in the workspace panel.

[MLnoob5340]

I figured it out--the cross pattern is supposed to be centered and is not supposed to touch the sides I just used a rectangle tool to create two perpendicular rectangles However, as a noob, I really appreciate your method, I think I can find how to manipulate it to get my desired image.

Thank you!

[Image Analyst]

You can go from 2 to (end-1). Here is how I'd do it:

m = 100*ones(10, 10, 'uint8')
row1 = 4;
row2 = 7;
m(row1:row2,2:end-1) = 255;
m(2:end-1,row1:row2) = 255;
image(m);
colormap(gray(256));
grid on;

[Omar Alabid]

Guys i need your help!!!! I have question Using a built-in function to create a 30 x 30 matrix, where the middle two róws and the middle two columns are filled with 2's while the rest are 4's.

[Image Analyst]

m = 4 * ones(30, 30);
m(15:16, :) = 2;
m(:, 15:16) = 2;