Setting Atlas Format to PNG?

[pusapusa]

I want to know 'how good' is the PNG option in Atlas Format, what exactly does?
I have a project with more than 500 png files in Resources folder (about 50MB in explorer) but due to resolution, Unity make it so big.
Example: myImage.png compressed in file explorer (100kb). In Unity (more than 10MB)
The PNG option make that image size prevent to descompress

[unikronsoftware]

The PNG option saves the the texture atlases as actual PNG files in the built project, so they will be quite small - considerably smaller than the unity assets, but this comes at the cost of load time. It takes a while longer to load textures this way than with normal unity textures and it uses more memory at runtime. The disk size for your app is considerably smaller though.