Exported png files get about 100 times larger than expected

[Grobe]

Hi.

Ok, so first - trying to upload the xcf file failed because of file size, so the only file possible to upload correctly is this png export settings.

Here is the file description.

• Layer 1 - importet PNG file, file size about 55kB
  
• Layer 2 - same dimension and roughly same size, but not same image.
  
• Layer 3 - New transparent layer.
  
• The layer 3 mainly consists of small spots of non-transparent pixels created with clone tool, so it's just to add/remove some features of a map.
  

The problem is that after exporting this image file to png format, the resulting file size get over 6MB - that is about 100 times larger, I expected the output png file to be maybe around 70kB at maximum.


Edit : Solved while edit this post

Ok, just figured the solution. The image precision was set to 32 bit floating point, and by converting to 8 bit integer, the exported PNG file became a nice 77kB file.

I post this anyway in case somebody happens to stumble upon same issue.