reducing dimension of an icon with Preview I had an png icon file of dimension 40*40 with a size of 2 KB. I adjust its dimensions with Preview app to get 25*25. I got the icon file converted to 25*25, but now its size is 3 KB. Why? As we reduce dimension, the size must get reduce. But it is not happening?
There are multiple algorithm to optimize the size of PNG files.
Preview is known to not be not optimal on that point. 

If you want to optimize the size of your PNG, there are multiple tools available on the web. 

Just by randomly searching on google :


https://pngquant.org/
https://imageoptim.com/
http://www.gingerbeardman.com/pngenie/