Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody"
<moodymz3@y...> wrote:
> What I meant by a true monochrome image is one where the intensity
reading
> of each element in the digital sensor independently maps to the
final image.
> With processing of sensor data with a Bayer interpolation routine, each
> pixel is a combination of its own intensity and some portion of
surrounding
> pixels.  In-camera jpegs and raw files converted with the standard
software
> will do this.
> 
> See David Burren's page, http://burren.cx/photo/e950ir.html for an
example
> of the difference in processing.  The fourth image down can be
moused over
> for comparison.  Note that this image was taken with a sensor
containing a
> bayer filter, so it would not meet what I referred to as a "true
monochrome
> image".  The filters on that particular camera are rather transparent to
> near-IR so it's darn close.

It's more than just "darn close". I use the same trick on my Nikon
D100, shoot through a Wratten 87, convert with Dave Coffin's DCRAW in
"document mode", then equalize the levels, and deviation is less than
1%, comparable to an actual monochrome sensor.

The filters on all cameras that I've ever worked with are pretty much
transparent to IR about 750nm.