Converting PNG/GIF for display - what size?

im looking for advise/guidance on converting PNG and/or Gif files to display on a display
the display consists of 3 rows of 5 2.5 panels.

Is there a recommended size to have the best quality display? is there a formula for doing this on the panel sizes and count?


I don’t understand your question
Calculate how many pixels you have X and Y in your display and resize to that.

If I am understanding you correctly, you are using a 3x5 matrix? If so, you have to resize your image in an image editor to 3x5 pixels. Though at the size your image will come out pretty blurry unless it was already a small image.