I don't know if I follow you here. The image size/quality is determined by the amount of pixels per inch. If you increase the pixels you increase the number per inch.
By increasing the size of the pixel you reduce the number of pixels per inch and lessen the quality.
In a camera a number of "pixels" is available on the sensor, sensor size determines how big these "pixels" are. The bigger the pixel in this recording stage the more info they can contain.
So in short in the input (recording phase you want as many and as big as possible, and in the reproduction stage you want as many and as small as possible.)
Hence making pixels larger is not productive and is simple by reducing the pixels per inch.
I am sure somebody else from ThinkCamera will be able to explain it better.
