About image resizing

Image resizing is done by pixel averaging and image sharpening. when you reduce the image size, program will average the surrounding pixels. when you enlarge the size, program will have to create new pixels. That's way enlarging alway give poorer quality. Nonetheless, your original picture will be processed one way or another. Good program like photoshop will digitally reprocess your photo so that you normally can't see difference by your eyes when you reduce the size. But you can try to reduce a 1600x1200 picture to a 80x60, then you will see a very poor quality picture.