Reflection map format

[h106frp]

In an old post it was stated that GPB supports reflection maps. Could you confirm the format for this shader? Is it just a grayscale image or a more complex structure?

I have experimented with a gray scale image assuming; towards black = lower reflection, towards white = higher reflection and gray=mean but i am not convinced of the result.

Thank you

[PiBoSo]

The reflection map is just a grayscale image.
Please note that only the alpha channel is used.

[h106frp]

Thank you PB i was wondering whether i should try the alpha channel