[HUG ] Re: IMG: Triptych

Hi,
I think the point he is trying to make is that when you scan or capture if you save it in Raw you get what the sensor saw at the time and if you save it to a tiff, dng or some other format you discard some of the data. tiff is a lossless format when opened but some of the data (not needed by the tiff file format)is stipped off the file before it is saved so the tiff file does not contain all the data the sensor saw but a raw file does contain all the data the sensor saw and nothing else, not even a color space profile. 

Franc
----- Original Message ----- From: "Austin Franklin" <austin.franklin@xxxxxxxxxxx> 
To: <hasselblad@xxxxxxxxxxxxx>
Sent: Tuesday, March 17, 2009 4:05 PM
Subject: [HUG ] Re: IMG: Triptych




Hi Mark,


A raw file is s digital negative
A tiff or Photoshop psd file is a contact print made from that negative.
    its darned good; but its not all there.
For a TIFF, I can't speak for a PSD file, there can be absolutely no loss at all. It can be absolutely %100 equal to "raw". It depends on what is done 
to the TIFF file.  If setpoints and tonal curves (or Bayer pattern
reconciliation) are done, then what you say is true.  But, there is no
requirement for a TIFF file to have that set. The Leafscan scans it's "raw" 
scans (no setpoints and no tonal curves) to TIFF files.

Also, all raw files are not the same.  The raw file typically does have
*some* level of processing done, at the very least the PRNU, and even more
so, the white balance (setpoints) and possibly some other processing.  So,
"raw" may not be as raw as you would like.  But, having the camera do some
level of processing isn't a bad thing, necessarily. Each sensor system can 
be characterized, and that characterization applied to the data to
calibrate/normalize it.  It's like having a "profile", like an ICC profile
for printing, or calibrating your capture/development/printing for film.
Everything is relative, and needs to have some level of calibration to be
effective.


Don't listen to me...


Sometimes I do, sometimes I don't ;-)


google it yourself


I don't need to "Google" it.  I know how image capture is done, since I've
designed quite a few digital cameras and scanners.  And you know that.

Regards,

Austin


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