Mike Taylor wrote:

> Or not.  Cheap cameras may well produce JPEGs that contain eight 
> million pixels, but that doesn't mean that they are using all or 
> even much of that resolution.

Does anybody have a printed test sheet that we can scan or photo, 
and then compare the resulting digital images?  It should have 
lines at various densities and areas of different colours, just 
like an old TV test image.  Can you buy such calibration sheets?

We could make it a standard routine, to always shoot such a sheet 
at the beginning of any captured book, to give the reader an idea 
of the digitization quality of the used equipment.

They are called "technical target" in figure 14, page 149, of
Lisa L. Fox (ed.), "Preservation Microfilming", 2nd ed. (1996), 
ISBN 0-8389-0653-2.  The example there is manufactured by A&P 
International, http://www.a-p-international.com/

However, their price list is $100-400 per package of 50 sheets.
I wouldn't pay more for the calibration targets than for the
camera, if I could avoid it.


-- 
  Lars Aronsson ([log in to unmask])
  Aronsson Datateknik - http://aronsson.se

  Project Runeberg - free Nordic literature - http://runeberg.org/