To control a cmos camera using nios II

You can use a fifo or dpram to buffer your image data, I recommend you use two buffers in a ping-pang structure.

If u use logic design in your FPGA to process the image data, you may not need the buffer(s), but if you use Nios to control the dataflow, the buffer is necessary.

By the way, if you want to store image(s) in RAM, you can use SDRAM instead of sram, cause the former is cheaper than the latter, of course this is due to how many images you want to store in your RAM.