php - I'm working on a website that sells different artwork, what's the best way to handle different image sizes? -

I am working on a website that allows users to upload and sell their artwork at different sizes . I was wondering what would be the best way to handle different file sizes automatically. I was curious at some points:

• Different size categories like this (small , Medium, large) How to define dynamically resized images with proportional dimensions?

• Should I store real JPGs of different sizes for download? Or downloading on the fly will be easy to create these different sizes

• My thumbnails will be slightly larger than your average thumbnail, I should store the second thumbnail image sites watermark it Overlaying? Or once again, produce it on the fly?

All opinions, advice is highly appreciated!

I do something like this.

There, some images are changed on the fly for the first time, and then they are stored; While the other uploads are created at time, the images requested in the group (i.e. thumbnail) are generated at upload time, and the images appearing at one time arise when they are flying. It worked well for me, but it is a lot of site without traffic.

I am working in Python and Django, so I use sorl-thumbnails for this. In PHP, you get to work with different image makers. * Functions that do the same thing (eg) .

I create watermark versions of pictures (if a particular album should be watermarked), and instead