LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
February 2004
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2004.02.10 23:37 "Re: displaying 12 bit tiff image", by Frank Warmerdam
Chris Cox wrote: > At 7:32 AM -0600 2/10/04, Liliana RESENDIZ wrote: > > > Hi Bob, > > > > The image comes from a CCD Thomson Camera (TH-8430), and it is saved on a > > 16-bit buffer, so the data range is [0,4095]. Finally i displayed it with > > libtiff libraries, but I think it can improve, i'll take a look to the > > DGM > > 1.1. > > > If it was saved as 16 bit/sample - then the data should have been scaled > to 0..65535. > (although several companies have made the mistake of not scaling -- it > is spelled out pretty clearly in the TIFF spec.) Chris, I would note that remote sensing sensor data is routinely distributed as 16 bits per sample, but with a dynamic range far from the complete 0..65535 range in order to preserve the original sensor results. In cases like this remote sensing applications are expected to scale the data themselves, and there are many approaches to doing that. My point is that while a "simple picture" that is stored as 16bit might need to be pre-scaled in the TIFF file in the range 0-65535, there are respectible reasons to deliver other kinds of "scientfic data" such that this is not done. Some kinds of applications should be prepared for this to happen. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent