how to capture certain area of screen

This is a matlab screen capture program that captures whole screen every one second and saves capture screen to a folder. I need to modify it to capture certain rectangular area of screen instead of all screen. Also i need to apply image processing on captured frames in real time i.e. immediately after they are captured. Please help.

%press (ctrl+break) to stop your program from capturing screen

 i=1;
while true
    robo = java.awt.Robot;
    t = java.awt.Toolkit.getDefaultToolkit();

    %# Set the capture area as the size for the screen
    rectangle = java.awt.Rectangle(t.getScreenSize());

    %# Get the capture
    image = robo.createScreenCapture(rectangle);

    %# Save it to file
    filehandle = java.io.File(sprintf('capture%d.jpg', i));
    javax.imageio.ImageIO.write(image,'jpg',filehandle);

    pause(300) %# Wait for 5 min
    i = i + 1;
end

Answer 1

[Sean de Wolski]

No reason to reinvent the wheel.

http://www.mathworks.com/matlabcentral/fileexchange/24323-screencapture-get-a-screen-capture-of-a-figure-frame-or-component

Answer 2

[sandeep]

The code you are referring to takes only one screen shot. I need a code that can capture certain area of screen continuously lets say fro one mniute and then stop.

[Sean de Wolski]

Okay, then call that function multiple times in a for-loop or even better with a timer.

[sandeep]

How with a timer, i am new to matlab.

[Sean de Wolski]

doc timer

Set the timerfcn up to call screencapture and do whatever processing needs to be done.

[sandeep]

Can u edit the code that i posted above so that it captures a certain area.

Answer 3

[Image Analyst]

Don't use image as the name of your variable since it's the name of a built-in function. Try this

screenImage = robo.createScreenCapture(rectangle);
subImage = screenImage(row1:row2, col1:col2,:);  % Crop it.

Then do your save on subImage.

[Image Analyst]

sandeep's reply moved here since it's not an answer to the original question, but a reply to me:

@ Image analyst, I get the meaning of first line in your code. But what kind of cropping will be done by second line. The code i posted captures full screen every 300 seconds and saves capture screen to a folder. I need to modify it to capture certain rectangular area on screen.... and then send the captures frames to image processing algorithm. Please help me here.

[Image Analyst]

The second line of code takes a 3D image - a color image - and extracts out a sub image (that is also color) into its own variable called subImage. The rest of your code with looping and saving can stay the same, except for the write line where you want to write this subImage to disk, instead of the whole screen image.