Can anyone explian the TWAIN interface?

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(08-23-2017, 06:29 PM)rich2005 Wrote: Gimp 2.8.x is 24 bit (8 bit x 3 channel) maximum, so even if your scanner produces 48 bit (16 bit x 3 channel) you will only get 24 bit.
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My more usual linux setup, and while this is Gimp 2.9.5 which will handle 48 bit (16 x 3)  the scanner driver (SANE) cannot handle that resolution. Still get 24 bit: screenshot http://i.imgur.com/Q4fsBE5.jpg
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For the rest of your question - data transfer, it will be some type of lossless format, SANE for example, while you can specify a format, defaults to pnm. As important is the ppi used for scanning, 300 for photo quality, increasing the ppi above about 600 is usually a waste of time.

I am using GIMP 2.8.18.  My reference to 8bit & 16bit pertains to both color & grayscale.  In that for color I also meant 24bit & 48bit.
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I'll be among the first to try GIMP 2.10 but because of my novice status have resisted the temptation to try a development version.  I suspect that GIMP 2.10 will provide a means for the user to explicitly inquire about this aspect of the image type whereas this isn't necessary for GIMP 2.8 which only does 8bit.
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If you are correct about lossless that addresses my primary concern but I tend to be curious enough to want to know the specifics.  It is helpful to know that even with GIMP 2.10 this support could be limited to 8bit which should explain why I wanted to know more about how/where any conversion from 16bit to 8bit is done.

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(08-23-2017, 07:41 PM)Ofnuts Wrote: http://www.eztwain.com/twain1.htm

Thanks!  This is the kind of information I was seeking.  The part about modes of image transfer somewhat answers my question.  The modes "Native" and "Memory" would have me betting on lossless methods, whereas "File" ought to conform to the specification for the type of file.  Insofar, as the interface I'm using with GIMP provides no awareness of any file creation I'd definitely be expecting "Native" or "Memory".

Since I think GIMP can open a file that uses the 16bit format it does seem that GIMP is capable of converting such to 8bit which still leaves open the question about who does it.  I'm suspecting GIMP because I don't think this is a capability that the source device maker would want to undertake.