Image Cropping on De2-115 using Verilog

[Altera_Forum]

Good Day. I'm currently doing signature verification on DE2-115 using Verilog. I need to compare two different images and I'm having trouble in cropping them. My system needs to crop both my test and genuine signatures which are both initially a 640x480 image. What i know is that i have to determine the rows and columns of the image that are non-zero.My problem now is how would i know the location of the non-zero rows and columns and the maximum value where i would crop it. Also the cropping itself, can I shift them to either right or left or is there another way?

[Altera_Forum]

That all depends on what you want to do. Please give us a complete description of your problem, and maybe of your whole system so that we can help you splitting your problem to simple chunks.

[Altera_Forum]

How are the images scanned into the system? as a raster scan (top left to bottom right)? If you know the order of the pixels then you should know which row/column you are on.