Is there anything like a flood fill algorithm for the transparent part of a png image?

So I wanted to do a maze game. after designing the maze in photoshop, I save it as png but of course when I export it to C3 or Unity, the program doesn't recognize the walls and gives it one collision box. Is there anything like an algorithm that detects the parts of a png file with transparency and flood fill the rest of the image? The result would be creating another layer with tiles overlapping the original layout but with the right collision box so that you can make it invisible and solve the problem.

I don't think so

However you could definitely use a tilemap for this

Insert a blank tilemap over your maze, then 'paint' all the tiles that make up the walls of your maze