How to apply a watermark with the same size for all photo sizes?

Question

PHP

Hello ;)
There is a script that puts a watermark from a png file (212x212 pixels) in the center of the uploaded image. Everything works ok.
The question is how to make sure that the watermark is applied with the same (or probably different) size.
Those. so that I open a photo 2000x2000 and I have a clearly visible watermark in the center. And so that if you apply 500x500 to the picture, then it was also in the center and occupied, say, 15% of the screen area, and not in all its 212x212.
I think the meaning is clear) Tell me how to implement.

Answer 1

Your question has half the answer, use the percentage depending on the picture