You can do it using iMovie as an intermediary. See the following link to bring the PhotoBooth into iMovie. I would add when selecting the resolution you would choose the higher 1024 x 768 resolution as you desire.
hello. thanks for your reply. i don't want to increase the resolution of an already taken picture by scaling it. that deteriorates the image. i want that the image themselves are taken at a higher resolution. with no direct way to do this, i guess the camera is only of 640x480 = 307200 = 0.3 Mega pixels.
The PhotoBooth camera is a simple uncomplicated camera. Just look at the size of the hole and you can guess the CCD (if it is a CCD) would be only about 1 mm big. You can't get blood out of a stone, any more than you can get hi resolution images from a cheap camera. So use it for what it is, but if you want better quality images, you'll need to buy a better quality camera.