Defined quality of uploaded images on server

[toplisek]

I like to know how to define server based quality of images which are uploaded. As we know there is upload solution based on file size and format. Can be checked quality of images as we know exact dimension (size) but quality is not defined and can influence printed result?

Is there some the best PHP solution for this particular issue?

[eelixduppy]

"Printed result" as in on paper?

If you know the resolution of the image and how large you are going to be printing it, you could technically calculate the ppi for that image to determine how nicely it will look when it is printed (assuming the actual printer you are using is decent). 200-300 ppi will produce the best results, but may be too large for what you're working with.

[penders]

The compression ratio used for JPEG images?