This is one of the best Picons database I have come across. It has almost all countries and for the majority of the channels. Some popular channels have both the icon (big and square shape) and horizontal (linear and narrow) shapes which you can choose from.
The direct link to their Github page is this > https://github.com/tv-logo/tv-logos
But since for whatever reason Github keeps disabling their profile, I have uploaded the file here > http://filedb.me/tv-logos-main.zip
The direct link to their Github page is this > https://github.com/tv-logo/tv-logos
But since for whatever reason Github keeps disabling their profile, I have uploaded the file here > http://filedb.me/tv-logos-main.zip