RE: pixels, bis

["Paul D. DeRocco" <pderocco@ix.netcom.com>]

> -----Original Message-----
> From: owner-epson-inkjet@leben.com
> [mailto:owner-epson-inkjet@leben.com]On Behalf Of Bruce Fraser
> Sent: Monday, August 20, 2001 9:50 AM
> To: epson-inkjet@leben.com
> Subject: Re: pixels, bis
>
> I'd also have to say that the sources that refer to a capture element
> in a CCD as a pixel are smoking stuff. It's the exception rather than
> the rule for a single capture element to form a single image pixel.
> Most CCD scanners use three capture elements to form an image pixel,
> and drum scanners form image pixels without using an array of capture
> elements. With striped-array cameras, each image pixel is typically
> formed from 4 capture elements. Calling a CCD element a pixel
> strongly invites the conclusion that there's a one-to-one
> relationship between capture elements and image pixels. This ain't a
> hill worth dying on, but to my mind doing so invites confusion.

All this means is that the pixels from the sensor elements, or from the
sample-and-hold on the analog voltage from the phototransistor, are
resampled to produce a different set of pixels. I would still say that the
capture elements produce pixels, just not the ones you eventually see in
your image file.

I think it's most useful to regard pixels as point samples. The fact that a
scanner or camera pixel physically captures light from a nonzero area simply
means that some two-dimensional filtering function has been applied before
point samples were taken. Similarly, the fact that a CRT or LCD pixel
physically generates light over a nonzero area means that some
two-dimensional filtering function is applied to the point samples. The
filtering function in a simple CCD or LCD is probably rectangular, while the
filtering function of a flying spot scanner or CRT is probably more
gaussian, the latter generally producing less aliasing.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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