Re: [APML]: Scanner Bit Depth

[Chuck Vaughn <aa6g@aa6g.org>]

The Astro-Photography Mailing List
------------------------------------

Philip,

>This is interesting, and it's very noticeable that as soon as I start to 
>mess with the contrast or curves that the noise starts to increase.  But I 
>still don't understand why the scanner has to convert from 12 bits to 8 bits 
>in the first place.

Most of the programs with which these scanners were intended to be used didn't
fully support (or support at all) 16 bit data so they had to convert to 8
bit data. This is beginning to change. I'd like to see Polaroid come out
with a version of software that exports the full bit depth to Photoshop.
I don't think this will fix the noise you are seeing though. The colored noise
is coming the adjacent RGB pixels digitizing to slightly different values
at the lowest levels. This calls into question the usefullness of the LSBs.
If they are just noise then there's not much point in having them.

Chuck  <aa6g@aa6g.org>