Sanitize & validate incoming images

[asqarslanov]

• Ensure images have aspect ratios between 21:9 (movie frames) and 9:21 (mobile phone screenshots).
  • Otherwise reject them (cropping is unexpected).
• Ensure images are not too small (2x3 px).
  • Or should we? What if a user sends a pixel art?
    • Then, how should we scale this image? Bicubic? Linear?
• Ensure images don’t exceed 10 MB in size.
• Compress images / reduce their resolution.

Relevant:

• Add an optional image size field when accepting new images.
• When sending images back to clients, attach their size.