Interfacing D5M camera to De1-SoC

Hello

I am new to FPGAs and am developing a project that implements a chroma key effect.

My inputs are a camera (Terasic D5M) and some control switches, and the output is displayed to the VGA monitor.

For the camera and VGA controller, I am using the codes provided be Terasic. The resolution in the code is 640 by 480 pixels. I would like to decrease the resolution to a lower value such as 256 by 256 pixels (I want to display to the VGA 256x256 pixels) . How can I do that?

I have attached the codes here

All help is appreciated

Thanks