Grab 20 lines and make a graph

center_row_data = img(415:435, 1:755);

plot(center_row_data);

title('Central Horizontal Line');

xlabel('Pixel Position');

ylabel('Pixel Value')

But the picture presented looks like there are many strips. Can anyone tell me?

[Dyuman Joshi]

"Can anyone tell me?"

I assume you wanted to ask why that happens.

You have provided a matrix as the single input to plot.

The output corresponding to that is a plot containing one line for each column in Y, where the x-coordinates range from 1 to the number of rows in Y.

[bozheng]

Thank you for your answer. Then how should I write the program?

[Dyuman Joshi]

What do you want to do?

[bozheng]

It just shows 20 lines. Do I need to give you a sample picture?

[Dyuman Joshi]

Yes, that would be helpful.

[bozheng]

[Dyuman Joshi]

Try imagesc or image

Answer 1

[Voss]

Maybe you want to transpose center_row_data when plotting it.

img = peaks(1000); % some img

center_row_data = img(415:435, 1:755);

subplot(2,1,1)
plot(center_row_data);
title('Plotting each Column as a Line');

subplot(2,1,2)
plot(center_row_data.');
title('Plotting each Row as a Line');

Answer 2

[Steven Lord]

I would suggest looking through the MATLAB Plot Gallery to determine if one of those thumbnail pictures look similar to the type of visualization you want to show. If they do, click the "Open and explore" link below the thumbnail to see an example Live Script in MATLAB Online that shows how to create that type of visualization. Use that as a model to visualize your data.

The example may not create the exact visualization you want, but it should help serve as a good starting point for your own code.