number of frames, sane_start, and sane_read

Tripp Lilley (tlilley@perspex.com)
Mon, 8 Feb 1999 03:16:03 -0500 (EST)

I'm almost to the point of actually acquiring images in my sane code, and
I'm a little bit confused by the notion of "frames". Well, I think I have
a rough understanding of a "frame" as a block of data, semantics
determined by the result of a call to sane_get_parameters.

Is a frame always a part of a single "image"? That is, I notice that
frames can be gray, RGB interleaved, or one of R, G, or B, which suggests
that it would take three frames to compose a single RGB image were the
backend spitting out R, G, B frames individually. But would I ever see a
backend spitting out multiple gray frames? For instance, if I had a camera
back end, spitting out so many frames per second?

Or is this just an unfortunate overloading of the word 'frame'?

If I have an automatic document feeder hooked up to my scanner, and the
user loads a bunch of docs and clicks "scan", with the ADF enabled, will
it require me to keep calling sane_start to retrieve subsequent pages? Or
will I have to call sane_cancel at the end of every page, then call
sane_start again?

Is it safe to assume that a single gray frame is one image, a single RGB
from is one image, and a set of R, G, and B frames is one image? Is it
ever possible that I would get a single R, G, or B frame on its own?

I just want to make sure I don't make any stupid assumptions in my Perl
wrapper :-)

Thanks for the help!

--
   Tripp Lilley + Innovative Workflow Engineering, Inc. + (tripp@iweinc.com)
------------------------------------------------------------------------------
  "So perl is like a graceful swan, gliding across a lake. But underneath the
   water, there's these little legs, paddling like buggery."


-- beable van polasm in http://www.dejanews.com/getdoc.xp?AN=440381254







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