LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
June 1999
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
1999.06.08 22:52 "Re: Large File Support", by Peter Smith
Thanks for this overview of another tiff application, Ed. We are using tiff files to store bitmap images that are downloaded to our "platesetters" - image recorders that directly expose aluminum printing plates. I thought we had large files, typically 1GB to 5GB uncompressed. Fortunately, there is usually a lot of whitespace, line art and text in these files so they compress well with G4 (up to 100 times). We aren't in any real danger of coming up against the big file problem, but I'm interested in following this discussion. Peter At 04:58 PM 6/8/99 -0500, Grissom, Ed wrote: > >Peter - > >Although your question was not addressed to me, I'll give you my input >anyway.... > >For uncompressed files, the limit has already been passed. Our >photogrammetric scanner is capable of scanning a 10"x10" aerial photo >negative at 3500 DPI in 24bit RGB. With a full set of overviews (required >for our workflows), this comes out to nearly 5GB uncompressed. Any >enhancements we might do to this product ( increase DPI, increase bit depth, >etc.) will only make the problem more pronounced. > >Unfortunately, compression is often not an option. PackBits does a pretty >lousy job on scanned photos, and is essentially unusable for >8bit data. >LZW is patented and both LZW and Deflate will typically only reduce these >types of images to ~75% of the original size. > >JPEG has been our savior so far, but some folks (especially in Remote >Sensing) are very particular about original pixel values and do not want to >use JPEG compression which modifies the data - however slight the >modification is. > >I have here on my desk two CD's, each containing a Wavelet compressed file >(LizardTech) that would be over 15GB uncompressed. These were created as a >mosaic of over a hundred TIFF files. Although the wavelet compression gets >them down to less than 650MB, there is nothing comparable in TIFF that would >allow me to convert these files (in their entirety) to TIFF. > >Recently a customer claimed to have a 40GB (uncompressed) file that he >wanted to convert to TIFF. If I remember correctly, it was 6GB compressed. I >am not sure what file format was used, perhaps NITF (NITF handles up to 17GB >compressed). > >If you ask me, Frank was understating the problem. :) > >-- >ed grissom >egrissom@ziimaging.com > >> -----Original Message----- >> From: Peter Smith [SMTP:psmith@creo.com] >> Sent: Tuesday, June 08, 1999 4:15 PM >> To: TIFF Mailing List; warmerda@home.com >> Subject: Re: Large File Support >> >> Frank >> >> When you say: >> >> "Within the remote sensing, and photogrammetry community the 4GB limit is >> becoming significant already" >> >> are you referring to files that are 4GB compressed or uncompressed? >> ----------------------------------------------------------------- >> Peter Smith >> mailto:plsmith@island.net >> mailto:psmith@creo.com (forwarded directly to the above address) >> Phone: 250-285-2294 > > ----------------------------------------------------------------- Peter Smith mailto:plsmith@island.net mailto:psmith@creo.com (forwarded directly to the above address) Phone: 250-285-2294