Proper Current Image Dimensions for GBP Posts and Offers?

[Gerry.Foster]

I have always used 540x405 as best practice for image dimensions, but those sizes now seem to get the infamous "black bars" on either side of the picture. Was there an update to image sizes that I missed somewhere (it's very possible, theres been a lot of updates to GBP this quarter).

Thank you in advance pros.

 

[Marcin Karwowski]

I use 1200 x 900 pixels, 4: 3 image ratio and it works fine. But the truth is, google scales these photos differently depending on the location: desktop search, desktop maps, mobile search, maps app.
I am not sure if there is a format that looks perfect everywhere.