Re: [APML] Dynamic Range of CCD

[Jerry Lodriguss <jml@astropix.com>]

>The ST10s have a 16bit A/D.


I thought the A/D only determined the bit depth OF the dynamic range.  I 
thought bit depth is NOT dynamic range.



>The dynamic range is less than this, about
>12 - 13 bits approximately depending on each individual detector due to
>lot variations. I believe this amount of dynamic range is more than the
>eye can discern especially if each RGB has so many bits.


  The eye has a tremendous brightness range that it can accommodate. 
Approximately from log -6 to +7 in luminance (log cd/m squared). Granted 
the eye doesn't accomodate this entire range at one time, but it can do 6 
long units just for photopic vision alone (see Hood and Finkelstein 1986).







>Hence it is
>common for CCDs to capture this amount of imformation but not be able to
>display it visually without some type of dynamic range compression such
>as DDP. How does this relate to f-stops besides the fact that both can
>be represented logarithmically?


This is a common problem for film too. Most films have a larger dynamic 
range than the paper it can be printed on, and you have to do some kind of 
compression, or cut off something at the ends.

If a CCD can take a picture, I don't see why the information can't be 
related in terms of f/stops.


JErry








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