Digital BW, The Print

> From: John Moody
>
> 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.

The Bayer filter is built onto the chip as part of the semiconductor fab
process, so it can't just be lifted off. Although people are experimenting
with chemical means of dissolving it, I'm not aware of anyone who's
succeeded. But if someone does, the more obvious application would be for
B&W photography, not just IR.

However, even for IR there is some benefit to the Bayer pattern, because the
three colors not only have different visible light responses, they also have
different IR responses. It's simply not the case than an IR converted
digicam will show everything in the red channel--the other two channels also
carry different images, providing an opportunity for bringing out different
features of a scene.

For instance, my Minolta DiMage 7, which has no IR block filter, generally
produces garbage in the blue channel when I put on my R72 filter, but two
good but different images in the red and green channels. Not surprisingly,
the red channel has the really dark skies, while the green channel has the
white leaves. Choosing the proportion of these gives me some artistic
control over the image that I wouldn't have if the sensor was monochrome.

On the other hand, a monochrome sensor would be much sharper.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...