[Tig] jpg vs tiff, (OT), Glenn Chan

Rob Lingelbach rob at colorist.org
Wed Mar 12 13:15:16 GMT 2008


So I've been comparing The Gimp's 8-bit capability with that of  
Cinepaint's 16+ bit.   (Photoshop also has 16 bit capability but I  
leave it out for now as I'm not working with it.)

A NEF (Nikon RAW) image opened in The Gimp shows a certain amount of  
fine detail.  The same image opened in Cinepaint shows a lot more  
detail, in that a textured suitcase on the other side of the room in  
the shot has all of its texture visible in Cinepaint and none in The  
Gimp.   So I would guess, that bit depth in RGB (and I think the NEF  
file is 12 bits) contributes significantly to luminance detail.   
Forgive what might be a basic question, but I've not gotten into color  
bit-depth as applies to Mac/PC paint programs before.

Reading an article at http://photo.net/learn/raw/ , there is  
substantial reference given that for print work, 8 bits are enough.    
I have read elsewhere this is not true, rather that 8 bits are fine  
for Web, but 16 bit TIFFs are de rigeur for printing.    And to think  
of the math: 12 bit TIFF = 4096 intensity levels for each pixel.  8- 
bit (such as JPEG) = 256 intensity levels for each pixel.  And here is  
the quote from the the URL above that I'm curious about:

"Actually 256 levels is enough, and all printing is done at the 8 bit  
level, so you might ask what the point is of having 12 bit data."

(article goes on with a good explanation of why 'upsampling' is almost  
always a good idea.)

Now I'd like to ask Glenn Chan, who has been working on plug-ins for  
Photoshop, if he would be interested in doing some open source work on  
plugins for Cinepaint, which is missing several that The Gimp  
offers.   The rewards will be numerous but not financial necessarily :~]
--
Rob Lingelbach
rob at colorist.org  http://www.colorist.org/robhome.html






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