Transparency around icons

I try to find someone who can help to solve an icon problem:
On some Android smartphones my icons are nicely cut out and transparent, but on others it just shows a dull grey square around the icon. How can I make my icons with the the dull square transparent and nice?

Thank you for giving some advice to me.
Greetings from Ouagadougou,

Urs

We have used an online service a lot:

Although the name contains favicon, the service does far more than that. They know what they are doing and are transparent. We have used it for actual favicons a lot (for web pages) and also for apps (SIL app maker stuff and also our own apps for the Google Play Store). If you want to use this, take the time to read all the help and look at each (not very obvious) tab, it is worth the extra few minutes. I always tick and opt-for “as much as possible”, because deleting is easy, if you get a few icons too many.

Nice detail: You can upload your icon even as a vector graphic and get super-crisp icon files; you even get to pick your own compression-level or no-compression.

hth

Dear Martin,

thank you for your helpful answer.

Urs