Hello,
In my best guess, I think you are looking for some sort of 'line detection'. Hough transform is a popular way to do this. The Image Processing Toolbox has this functionality. Look here: Hough Transform in MATLAB
Once you identify the lines/edges, you should be able to compare with the original image using functions such as imabsdiff to locate and remove lines. This is easier to do using the first approach of line detection since it more or less directly gives you line locations..
If you don't have the image processing toolbox, I suggest you use google to see the best resource to implement one of the above 2 functionalities using basic MATLAB code. Particularly 'edge detection' should be fairly straightforward to do using just MATLAB.
Best, Swarooph
