Screenshot sizes on BlackBerry app world?

[psychicsoftware]

Has anyone figured out the optimum size for screenshot images for PlayBook apps on BlackBerry app world?

- all they tell you is that the maximum is 640x640.. however the screenshots shown when viewing app world on the device are widescreen aspect ratio

Does this mean that something like 640x360 is the best you can do, to fill the available screen space and have a correct aspect ratio? (assuming 16:9)

[psychicsoftware]

OK, I had to figure it out by trial and error, since RIM seem to want to keep it a secret.

What worked best for me was a 640x360 image. This fills the visible frame on the app preview page without visible distortion, although of course they apply heavy lossy compression for some reason and make it look less than perfect.

edit: I assume 640x375 is actually a bit better, since that's the correct aspect ratio for the PlayBook screen