digital cameras

From: Dwight Elvey <elvey_at_hal.com>
Date: Wed Jul 14 15:38:00 1999

Scott Ware <ware_at_xtal.pharm.nwu.edu> wrote:
> On Tue, 13 Jul 1999, Lawrence LeMay wrote:
>
> Consumer digital cameras generally use a single CCD as the imaging device.
> Since CCDs are monochrome, "color" CCDs are produced by applying a dye
> filter to alternating pixels in the CCD array to change the hue that
> different pixels are sensitive to, in a pattern such as
>
> RGRGRG
> GBGBGB
> RGRGRG
> GBGBGB

Hi
 As far as I know, most only use two color filters.
They infer the other color by having an unfiltered
pixel and subtract the signal from the others. The colors
of the actual filters depends on the manufacture. Some
times it is a magenta/red, a red/green or some other
combination with a clear filtered pixel. Blue is
rarely filtered because of two reasons. One is
that because of the fact that they make dielectric
filters and the layers for blue are harder to do.
Also, the sensitivity of the CCD drops off in the blue
so filtering of blue decreases signal/noise ratio.
The effect we see does look like RGB, inside, but
really isn't.
 Also, the pixel size isn't the same for all of them.
They are usually layed out in a 4 by 4 array with on
input coming from a two pixel width.
Dwight
Received on Wed Jul 14 1999 - 15:38:00 BST