Digital BW, The Print

The color interpolation I mentioned applies to digital array sensors like
those found in most digicams and DSLRs, not film.
Excepting the Foveon sensor, digital photographic sensors have a patterned
filter over the imaging chip, allowing the creation of a color image from an
otherwise “colorblind” sensor.  A search for Bayer filter will provide more
details.
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.

John

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
lulalake_1999
Sent: Wednesday, June 01, 2005 7:48 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] digital IR conversion

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody"
<moodymz3@y...> wrote:
> Full conversion includes removal of the Bayer color filter array; not
at all
> easy.  A filter to block the visible light as well.
> Then, you need to process the raw files without colour interpolation,
for a
> true monochrome image.
>
> John

Having shot thousands of IR pics, film and digital I'm interested to
hear what you mean about "color interpolation". Could you expand on
those thoughts a bit and describe what a true monochrome image is?

Thanks

Jules





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