I create artwork on Photoshop and occassionally print this artwork on physical products. That said, I save all of my artwork in PNG since is of better quality and has transparency.
Shen you save a PNG on Photoshop (not Save for Web as 300ppi needs to be retained), I am prompted with a small window that gives me the options for compression.
I am presented with "None/Fast" and "Smallest/Slow". When I take use "None/Fast", my file size is around 300Mb. However, when I use "Smallest/Slow", my file size drops down to about 3-5Mb. This is a tremendous file size reduction.
Afterwards I open both of the saved files (the 300Mb and 5Mb), and they are identical on screen and both have 300ppi retained.
What's the catch here? It seems to good to be true to have the file size compress to this tiny size without any visible quality loss (I'm zooming right in, no difference). Thank you.