Thread-topic: [filmscanners] RE: color bit depth and digital cameras
I also always shoot raw plus SHQ jpeg. The E-1 raw is 14-bit. Very good
insurance, and I always process the raw file for anything I'm going to
print.
Berry
On 7/14/07 9:14 AM, "Bob Geoghegan" <bobgeo@dgiinc.com> wrote:
> I wonder if the confusion comes from the option for compressed NEF as the
> raw format. The D200 default is uncompressed & lossless but it's easy to
> change to the just barely lossy compressed option. Compressed in-camera
> squeezes the 12 bit, 4096 native analog RAW value scale into 683 values,
> ~9.4 bits but differently allocated. Nearly all the compression loss is in
> more highly gradated high values. In uncompressed RAW, the top 4 stops use
> 3840 (2048+1024+512+256) values of the 4096. The remaining 256 values cover
> the rest of the 8 bits. Compressed NEF's allocate 251 values to the lower
> 256 (8 stops) and the remaining 432 to the top 4 stops (3860 raw values).
> The result is just a little less recoverable highlight data -- on average
> more values per f-stop than the lower range. The loss seems to empirically
> provable but hardly ever meaningful in the image. I still shoot
> uncompressed NEFs just in case. The D80, D70, D50 & D40 bodies only have
> compressed NEF.
>
>
> .html
>
> Bob G
> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of Berry Ives
> Sent: Saturday, July 14, 2007 8:05 AM
> To: bobgeo@dgiinc.com
> Subject: [filmscanners] Re: color bit depth and digital cameras
>
> Dpreview.com's review indicates that it is a 12-bit raw format.
> ~Berry
>
>
> On 7/13/07 11:27 PM, "David J. Littleboy" <davidjl@gol.com> wrote:
>
>>
>> From: <ppatton@bgnet.bgsu.edu>
>>>>>>>>>>>>
>>
>> I was just playing with my new Nikon D200 and discovered
>> something that surprised me. Unless there is some quality
>> adjustment setting I missed, it's color bit depth apparently is
>> only 8 bits in NEF Raw. By comparison, my Polaroid SprintScan
>> 4000 scanner has a color bit depth of 12 bits, and other scanners
>> have much higher color bit depths than this. While color bit
>> depth is a commonly cited specification for scanners, I've seldom
>> seen it cited for digital cameras. Does the lower bit depth for
>> the D200 imply lower quality color rendition than my 12 bit scanner?
>> <<<<<<<<<<<<<<<<<<<<<<<<<<
>>
>> I suspect you've done something wrong. This reference
>>
>>
>
> de
>> x.html
>>
>> Shows the D200 doing very well indeed at ISO 100. I'm quite sure it uses a
>> 12-bit A/D converter.
>>
>> Note that just because a camera or scanner has X bits in its A/D converter
>> doesn't mean you have X bits of valid data in the output files.
>>
>> David J. Littleboy
>> davidjl@gol.com
>> Tokyo, Japan
>>
>>
>>
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