RE: [APML] Dynamic Range of CCD

[Jerry Lodriguss <jml@astropix.com>]

At 04:08 PM 4/5/2002 -0700, you wrote:
>Jerry, one could argue that 16 bit cameras are 16 stops I think.


Hi Chris,

I don't understand.  I just don't know that much about CCD cameras.  When 
they say a scanner is 16 bits, they are talking about how many steps of 
tone there are between the black and the white.

The A/D convertor takes whatever analog voltage signal there is between the 
minimum usable signal and the maximum usable signal, and divides it up into 
steps. The number of discrete steps is the bit depth.

In my understanding of the definitions, the dynamic range is defined as the 
amount of difference between the maximum and minimum amount of light that 
the device can accurately record with detail.

Just as color negative film can record a greater brightness range than 
color slide film, it seems that the same must be true for CCD cameras.

We can divide this range up into how ever many steps we would like, and 
this is what I define as the tonal resolution and it is specified in bit depth.

So, you could conceivably have a very large bit depth but still have a 
small dynamic range.

Is this all wrong for CCDs?


Jerry

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