10 Jun
2006
10 Jun
'06
9:25 a.m.
Chris M wrote:
now an even better idea then a scanner is a digital
camera. 2 - 3 megapixels (even 1.2!) is sufficient for
archiving text and graphics. It MUST have the ability
where you can vary the focal length (able to move a
fixed focus lense in and out in relation to the image
sensor. And you thought I wasnt going to say that all
wrong?). I would also deem ancillary storage (i.e
cflash etc) a necessity. Cheaper to ship then a
scanner. Flat bed scanners are unwieldy, especially
when it comes to archiving bound stuph.
What you propose is something to do if you are desperate, but not
something you'd want to do routinely.
Taking a picture of an 8.5" x 11" sheet of paper with a 1.2 mpix camera
would get you 113 DPI.
In reality, it is worse than that. 99% of all digital cameras lie about
their DPI -- a 1.2 mpix camera doesn't have 1.2 mpix red, 1.2m green,
1.2m blue sensors. Different sensors have different patterns, but
essentially they count each r, g, or b subsample as a pixel and
interpolate. a common pattern is a tiling like this
R G B G
G B G R
Heavy duty image processing does its darnedest to hide this fact, but it
is obvious in certain circumstances. Take a picture of a B&W newspaper
from some distance where you will get some aliasing and
then look at the
picture -- you'll get lots of color fringing. The only camera
sensor
that doesn't do this is the one from foveon:
http://www.foveon.com/
This is a nice tie in to classiccmp -- the CEO of Foveon is Federico
Faggin, co designer of the 8080 and co-founder of Zilog.
Finally, the linearity of cameras is horrible for work like this, so the
effective DPI will drop even lower.