> Any comments about using JPEG2000?, this is a lossless file
> format like TIFF, but compressed to create much smaller
> files. I know this is increasingly being used by large
> digital repositories, but does anyone have comments about
> storing digital images using JPEG2000? My application is for
> storage of digital archaeological fieldwork photos.
TIFF is first a foremost a uncompressed file format used to hold
valuable image information. In Photoshop and other imaging packages,
compression can be applied but it is not used that often by
professionals; the three variations offered in Photoshop for TIFF are
lossless, but compressed. I only use them for files made very large
by applying many Photoshop Layers, then, I use ZIP which is lossless.
TIFF is not a lossless file format. Lossless compression protocols
can be applied to the uncompressed image information and stored in the
TIFF file "holder," but it is not a "compression" format.
JPEG2000 is an image compression format. Its output can range from
lossless at 2:1 to 3:1 compression, to heavier compression that will
alter file information (and I don't consider lossless). I would not
hesitate to use J2K it in the "lossless color" (LLC) mode, but would
think hard about using it on highly worked and color accurate image
files. That is, I make facsimiles of art works for institutions,
artists and clients. These files are captured with great effort, then
they are heavily worked to insure color accuracy. I see no reason to
compress these files.
However, if I was creating and saving images from DSLR camera of a
worksite or artifacts, slight alterations during compression, which
will decrease the space needed for many thousand large files might be
OK. The J2K format is always superior to the JPEG format. Remember
that HDDs are very inexpensive. A 1.5 TB Seagate with 32 MB of memory
can be had for $120 ($30 more for an enclosure). You should save a
minimum of 2 copies of each file, three if you can, on separate HDDs.
If you are saving the RAW and one TIFF version (15 MB RAW and 70 MB
for the TIFF = 85 MB total) the HDD will hold about 18000 images.
Your big costs will be in the backups, not the HD space for thousands
of images.
I made a study of the lossless capabilities of JPEG2000 with reference
to several large still image files a few years ago. The "still image"
data was stored in a private part of the
<videopreservation.staford.edu> website; although it had noting to do
with video. Do to a recent change in URL, you can now find it at
<http://206.180.235.132/tjv/index.html>. In addition to evaluating
the lossless capabilities, a comparison was made with the JPEG format
to show the degree of image change made using a well known image
compression format.
The problem with JPEG2000 is implementation. There are just few tools
available, with the best one being a "command line" program: Kakadu
<http://www.kakadusoftware.com/Downloads.html>. There are other
options, but they do not have as much control as the KDU command line
program. I used LEAD J2K Photoshop plug-in
<http://www.leadtools.com/Utilities/PSPlugIn/PhotoShop_plug-in.htm>,
there are others. J2K aficionados see all of them as less than ideal,
but acknowledge LEAD and Photoshop (CS2 1.6) plug-ins as a useful
tools that have GUIs.
Moscow State University has a review of nine J2K programs
http://compression.ru/video/codec_comparison/jpeg2000_codecs_compariso
n_en.html. As an aside, they also offer some great tools for
measuring video compression capabilities.
There is nothing simple about using JPEG2000, but the tool is far
superior to JPEG and can be done using existing Photoshop plug-ins.
Tim Vitale
Paper, Photographs &
Electronic Media Conservator
Film Migration (still) to Digital Format
Digital Imaging & Artwork Facsimiles
Preservation & Imaging Consulting
Preservation Associates
1500 Park Avenue
Suite 132
Emeryville, CA 94608
510-594-8277
510-594-8799 fax
[log in to unmask]
Albumen website (2001) http://albumen.stanford.edu/
VideoPreservation Website (2007) http://videopreservation.stanford.edu
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