[gdal-dev] Alpha band data type

[Evert Etienne (SITEMARK)]

Dear all,

I was wondering if there is a best practice or guide for the data type of alpha channels in geotiffs.
I have many files where the data type is constant over all bands (UInt16 for example). 
I would expect the alpha band to be a byte band or even bit.

Is it possible to have different types in a single file? If so, can I change the type of the alpha band alone to see if it has impact on the file size for example?

Many thanks

Evert