Funny, this morning I was doing a similar experiment but in the opposite
direction. I was curious if the 5MP from a 5MP digicam (Canon S60 in
this case) are really holding 5MP of real information or if there are
"invented" pixels there. So I took pics with the same subject at nominal
5MP and the other MP sizes supported by the camera (3MP and 2 MP, and I
didn't bother with the 640x480). I resampled the 3 and 2 MP images to 5
MP and compared with the genuine 5MP image. The 2 MP obviously lost some
fine details, however the resized 3MP one was oh so similar to the 5MP
one, except some JPG artifacts in a grass covered area. Except those
artifacts, the fine details were virtually identical.
Jens Bladt wrote:
Theres is realy very little difference between the to files - except for the
file size.