Re: Olympus to implement in-camera automatic HDR imaging?
- From: Wolfgang Weisselberg <ozcvgtt02@xxxxxxxxxxxxxx>
- Date: Sat, 30 Jun 2007 20:37:54 +0200
gowanoh <fac_187@xxxxxxxxxxx> wrote:
If I understand this it is really a way to try to read data twice off one
sensor at least twice during what will constitute a single exposure (short
and long) so that gain can be adjusted for dark/light and merge the two.
This would not require merging two complete images, although it might, but
only parts of the image that are out of exposure range to try to increase
the apparent latitude. The description mentions that if movement is
detected, meaning a change in image data from the short to the long
exposure, the long exposure is discarded.
I have wondered since the beginning of digital time why such a system could
not be implemented.
For the same reason we prefer single-exposure cameras to
scanning backends or "one chip, 3 filters in succession"
methods, even though they can deliver superior results:
Subject movement.
Otherwise I would have an even better solution: a short(ish)
exposure or two to find out the relative light levels, then
extrapolate that so that the sensor well is nearly, but never
completely, full. Make a long(er) exposure, which is
interrupted pixel-by-pixel as they reach their calculated
"full" exposure. The exposure time for the single pixel and
their (now exactly) measured fillgrade gives you the exact
strength of light with practically zero noise in the dark,
at the cost of a much longer exposure.
Olympus is positioned to do this with its "live view" dual sensor dSLRs: why
can't imaging data be incorporated from both sensors?
Because they are not aligned 100% and they do not cover the
same field of view.
You may also try and read up on 3-chip cameras. This technique
is used in (more expensive) video cameras and has long been used
in professional equipment, but not in still cameras. Guess there
must be a reason, since the pay-off (much better colour resolution,
better luminance resolution) would be good to have. IIRC they
have been experimenting with these things ...
Based on my limited technical expertise this could be a more complex but
technically better solution than the Kodak change to the Beyer filter which
would seem to have to lead to less imaging data coming off the sensor.
Kodak is simply reducing the colour resolution for a higher
luminance resolution and luminance suscepibility. I would have
preferred a dedicated b/w camera (with full luminance resolution,
and at least the same sensitivity), but ... who wants b/w these
days?
-Wolfgang
.
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