Different capture resolution for webcam

Could anyone tell me how i can change the capture resolution for my webcam? It seems that it captures the images at 320x240 resolution while it is capable of 1280x960 at 1fps/s but i’d like a 640x480 resolution, how can i change that? I’ve looked at the v4l tools but i failed to find any option to do that.

For example: with luvcview query the valid video formats and control settings (options -L and -l). Set with -s option.