Tom,
I am aware of a ~6million pixel CCD area imager
soon to be marketed (donno when). This CCD, as I
understand, has the area of ~2.7um2 per pixel.
Today's 2.5~3million CCDs employ ~3.4um2 pixel.
I think with this high density CCDs I feel there
should be no impact to the image degradation for
still image capture operations. As you might know,
the high-end/professional digicamcoder have
three CCD units with independent RGB filters.
Of course there will be some image degradations
whenever you start adding any elements in front
of the sensors. But with improved wafer processing
at the fab and with digital signal processing(DSP)
applications, I think the image degradation due
to what kind of optics used are no longer issue.
I think the real issue is mass storage scheme and
storage capacity of the captured data.
In case of film, the captured data is 'implanted' on
film. However, in case of digital images, the data
must be transfered out of CCD via shift registers
and stored on ather storage media such as flash
memory devices on the camera. Somewhere along the
the data transfers, the image data gets compressed
maybe such as .jpg or .gif format and gets decompressed
thus causing image degradations right there.
The flash memories, which are usually used for the
digicams, have their storage capacity limitations.
I believe today's commercially available flash memory
capacity is 4meg bit (may be I'm wrong). But the
point is the larger the data, the less number of
reproducible frames becoms - much less than 24
exposures of frames equivalent to the film.
With today's silicon wafer processing technology,
I do not see the drastic improvement of the rapid
access time of the data with the mass storage flash
devices (rapid access of the memory more implies with
video signal processing - not still image) unless by
employing the storage device like static random memories
(SRAM), which has its own characteristics - non-volatile.
Just my thoughts.
Jim Terazawa
> Hi Jim
>
> I believe they're in microns. To see the grain, the CCD elements
> would have be 1/2 the size. If the CCD pixel is about the same size,
> there'd be a bunch of intereference scanning film. I haven't come
> across any book that treats both optical & digital considerations.
>
> Tom
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