Earlier this month, the JPEG 2000 Implementation Working Group, the Wellcome Trust Library, and the U.K. Digital Preservation Coalition hosted a free one-day seminar called JPEG2000 for the Practitioner. The presentation slides are now linked to the seminar program and is a short report of the event by Christy Henshaw of Wellcome Library. The presentation slides by themselves carry a great deal of depth even without a recording of the audio. In particular I can recommend “What did JPEG 2000 ever do for us?” by Simon Tanner and “JPEG 2000 standardization – a pragmatic viewpoint” by Richard Clark. As brief introductions to where we’ve been with JPEG 2000 and where we could go.

Hat tip to Ron Murray for pointing this out to me.

The lead article in the September/October issue of D-Lib Magazine release yesterday is on djatoka, the open source JPEG2000 Image Server from Los Alamos National Laboratory. The authors, Ryan Chute and Herbert Van de Sompel describe their effort in the article abstract:

The ISO-standardized JPEG 2000 image format has started to attract significant attention. Support for the format is emerging in major consumer applications, and the cultural heritage community seriously considers it a viable format for digital preservation. So far, only commercial image servers with JPEG 2000 support have been available. They come with significant license fees and typically provide the customers with limited extensibility capabilities. Here, we introduce djatoka, an open source JPEG 2000 image server with an attractive basic feature set, and extensibility under control of the community of implementers. We describe djatoka, and point at demonstrations that feature digitized images of marvelous historical manuscripts from the collections of the British Library and the University of Ghent. We also call upon the community to engage in further development of djatoka.

The article is very easy to read and is a great overview of how they built the djatoka image server. LANL has a demonstration site with images of the Magna Carta from the British Library. The University of Ghent has also deployed a djatoka installation with some digitized pages of a Gregorian choir book. (The text of the site is in Dutch, I think, but you can click on the square boxes to the right of “Fol.” to bring up the images.) LANL has also put together a screencast demonstration of djatoka, included below.

djatoka is available under the GNU Lesser General Public License. The software has a site on SourceForge with forums for discussion. It runs as a Java servlet, so it is pretty much cross-platform. In the image server is the Kakadu JPEG2000 toolkit and the IIPImage JavaScript Viewer toolkit. One other key piece is a fascinating use of an OpenURL ContextObject to carry the service request information from the browser through the image server to the caching and rendering pieces.

Congratulations and kudos to Ryan, Herbert, and the team at LANL for putting together this great piece of software and releasing it as open source.Ryan Chute, Herbert Van de Sompel (2008). Introducing djatoka: A Reuse Friendly, Open Source JPEG 2000 Image Server D-Lib Magazine, 14 (9/10) DOI: 10.1045/september2008-chute

In reading a background paper for the American Social History Online portal, I was reacquainted with a paper by Muriel Foulonneau, Thomas Habing and Tim Cole from UIUC called “Automated Capture of Thumbnails and Thumbshots for Use by Metadata Aggregation Services.”¹ This is the abstract:

The practice of including thumbnails in short record displays, increasingly common in local implementations, is being adopted by metadata aggregation service providers as well. In addition, thumbnails and Web thumbshots have begun appearing as part of Web search results. This article reports on a project at the University of Illinois at Urbana-Champaign (UIUC) to make more comprehensible heterogeneous resources available on the UIUC CIC metadata portal by incorporating thumbnails and thumbshots of image and Webpage resources in the context of the OAI Protocol for Metadata Harvesting. In addition to thumbnails provided by partner data providers, UIUC has developed an automated process to generate thumbnails and thumbshots from the Webpages resources pointed to by the metadata records.

The paper cites dissatisfaction with results from metadata portals that consist exclusively of textual descriptions of the objects. It also cites studies that show the addition of thumbnail images to the results display improves user satisfaction. With that in mind, UIUC wrote Thumbgrabber — a Windows application written in Visual Basic that uses Internet Explorer to find images in websites and/or take image snapshots of web pages as they have been rendered. In the UIUC context, the application is fed URLs from records harvested via OAI-PMH, although it would seem like it would be able to process any arbitrary list of URLs.

This is a useful tool to keep in mind as we think more about aggregating the metadata records into vertical (subject-specific) portals and repurpose metadata records in other ways.

The text was modified to remove a link to http://cicharvest.grainger.uiuc.edu/thumb.asp on January 28th, 2011.

Footnotes

1. Foulonneau, M., Habing, T.G., Cole, T.W. (2006). Automated Capture of Thumbnails and Thumbshots for Use by Metadata Aggregation Services. D-Lib Magazine, 12(1) DOI: 10.1045/january2006-foulonneau

On the ImageLib mailing list, Rob Lancefield (Manager of Museum Information Services for Wesleyan University) posted a link to the Universal Photographic Digital Imaging Guidelines (UPDIG) for image creators. The introduction says: “These 12 guidelines — provided as a Quick Guide plus an in-depth Complete Guide — aim to clarify the issues affecting accurate reproduction and management of digital image files. Although they largely reflect a photographer’s perspective, anyone working with digital images should find them useful…. This document, prepared by the UPDIG working group, represents the industry consensus as of September 2007.” The listed members of UPDIG leads one to believe that this is a professional photography group. One thing in the introduction to the guidelines caught my eye, though:

The chapter on archiving now has a discussion of JPEG as an archival format.

Note that the authors do indeed mean JPEG (circa 1994), not JPEG2000. The chapter on archiving lists the pros and cons of a number of formats, to include JPEG. The following bullet points are excerpted from the text.

• Conversion to TIFF files: By converting images to TIFF format [from camera RAW], the photographer is storing the images in the most accessible file format… There is a downside, however. TIFF files are much larger than RAW files… Another downside to conversion to TIFF is that it precludes the use of better RAW converters that are surely coming in the future.
• Archiving JPEG files: Conventional wisdom holds that the TIFF format holds a quality advantage over the JPEG format. This holds true only if the JPEG file is saved at less than 10 quality using the Photoshop standard. When using JPEG quality 10 or 12, the artifacts are either non-existent or insignificant. Higher bit-depth is really the only advantage of using TIFF over JPEG 10 or 12 (in terms of image quality)… Update 2008-02-11: Please see below.
• Archiving RAW files: If a photographer chooses to archive the RAW file, then he will be preserving the largest number of options for future conversion of the files… This, too, has its downside. RAW files will likely have to be converted to a more universal file format at some time in the future.
• Archiving DNG files: RAW files can be converted to DNG, a documented TIFF-based format created by Adobe that can store the RAW image data, metadata, and a color-corrected JPEG preview of the image. The DNG file format provides a common platform for information about the file and adjustments to the image… DNG is likely to be readable long after the original RAW format becomes obsolete, simply because there will be so many more of them than any particular RAW file format… There’s a downside to DNG, of course. Conversion to DNG requires an extra step at the time of RAW file processing; it does not take terribly long, but it is an extra process.

Update 2008-02-11: Ken Fleisher noted in the comments that the excerpt above was truncated before his reasoning was described. In the interest of clarity, the full text of this bullet point on the UPDIG site is:

Archiving JPEG files: Conventional wisdom holds that the TIFF format holds a quality advantage over the JPEG format. This holds true only if the JPEG file is saved at less than 10 quality using the Photoshop standard. When using JPEG quality 10 or 12, the artifacts are either non-existent or insignificant. Higher bit-depth is really the only advantage of using TIFF over JPEG 10 or 12 (in terms of image quality). Some have argued that that JPEG, because of the way it encodes data, compromises color. This is a misconception. When using the highest quality settings, there is no loss of color fidelity. Therefore, if JPEG files are saved at 10-12 quality, and if they do not require much pixel editing before use, archiving JPEG files is not a bad concept, and it can save a lot of space. For many picture archives, the economics of storing large numbers of files dominates all other considerations, and JPEG offers a feasible solution to the problem.

The notes at the end of the chapter say: “The archiving JPEG section is based on research and analysis by Ken Fleisher.”

So I wonder what is going on here. Does the cultural heritage community have a different definition of the word archive from the professional photography community? Are there sufficient differences in our goals that warrant the differences in practices?

This topic is of interest because the program of the JPEG2000 in Archives and Libraries Interest Group of the Library and Information Technology Association (LITA) will be holding a panel at the ALA Annual Conference in Anaheim this summer on using the JPEG2000 file format for archival purposes. Part of the discussion will center around the notion of visually lossless versus data lossless compression. This mention of lossy-yet-high-quality JPEG compression seems to fit into the same topic.

The text was modified to remove a link to http://www.ala.org/ala/lita/litamembership/litaigs/jpeg2000/jk2kig.cfm on June 9th, 2011.

Xerox and the Library of Congress announced a joint effort last week to study the use of JPEG 2000. This is welcome news! The project is “designed to help develop guidelines and best practices for digital content,” a result that will be most welcome for those of us that want to do the right thing but lack the time and/or technical expertise to pin down exactly what the right thing is. I think it is safe to say that inertia has taken us this far with our collective TIFF-based practice, and even the most conservative preservationist would probably acknowledge that the state of the art has moved in the past quarter century to a point where there might be a better way.

I’m familiar with Rob Buckley’s work at Xerox, and that he is overseeing Xerox’s efforts in this collaboration means we can anticipate a great outcome. As others have noted, the time is ripe for work in this area.

On Tuesday, the Joint Photographic Expert’s Group (a.k.a. “JPEG”) announced a new work item for the standardization of Microsoft’s HD Photo as JPEG XR (XR is short for “extended range” — a reference to its improvement over the original JPEG standard). You can read the publicity details in the Microsoft press release and the JPEG press release, but beyond the public relations pieces I wonder if you are thinking about HD-Photo/JPEG-XR for digital archiving. And if you’re thinking that I’ll bet your wondering about how HD Photo compares with JPEG 2000. As with many things, the devil is in the details, so here is a first, gut-reaction pass at the details.

Standards Free of Intellectual Property Concerns

HD Photo’s Technical Advantage?

This seems to be the only claim of superiority to the JPEG2000 standard. Perhaps it is telling that HD Photo lives in the Windows Hardware Developers Central area of the Microsoft website — it is a standard intended for embedded devices (cameras, etc.). Even if it were true that JPEG2000 is more computationally intensive for compression and decompression, at the rate of general processor speed improvements is this enough to justify a new standard? Perhaps it makes sense for today’s marketplace of digital cameras; I don’t think this justification holds much weight in our community.

But What About the Metadata?

And Other JPEG2000 Advantages?

As the saying goes, “Never Put All of Your Eggs in One Basket.” Digital archival formats is one exception to that rule: simplicity — fewer baskets — is important. Fewer baskets — fewer file formats — means less to keep track of over time. Part 3 of JPEG2000 family of standards is called “Motion JPEG2000,” and as the JPEG committee press release describes, the “JPEG 2000 [Part 3] based DCI specification 1.1 [will be used] for distribution of digital movies to theatres/cinemas worldwide.” A file format used by the motion picture industry, with its deep pockets, for the production and distribution of movies is a standard that has a greater chance of standing the test of time. So a JPEG2000 practice — our one “basket” — can preserve both our still images and our moving images file formats. HD Photo does not have a corresponding moving image format.

What is HD Photo’s Compelling Advantage?

Truth be told, this analysis of HD Photo versus JPEG2000 isn’t based on any empirical evidence — it is just what my gut is telling me based what I’ve read so far. What we do for the long term preservation of cultural heritage materials shouldn’t be based on anecdotal analysis, though. Gut reactions and/or evidence from others are welcome.

Footnotes

1. HD Photo Specification Download. Version 1.0 dated November 16, 2006. Date Visited: Fri Aug 03 2007 16:45:27 GMT-0400 (EDT)

As a part of work for an OhioLINK strategic task force, I have been exploring the creation and operation of regional/collaborative/shared digitization centers. This is a report of findings to date after an open call for information. The report is structured with questions to be explored when considering a regional digitization center followed by narratives from conversations with the Collaborative Digitization Program (formerly the Colorado Digitization Program), the Mountain West Digital Library, and the Ohio Historical Society. My thanks go out to Leigh Grinstead, Liz Bishoff, Karen Estlund, Angela O’Neal, and Phil Sager for their assistance.

I am still interested in talking with collaboratives about similar programs, both “on the record” and in private conversations. Please get in touch with me if you would like to chat.

Questions for Exploration

1. Who does the digital conversion? Is it staff at the hosting institution (where the equipment is located), or does the institution contributing the materials perform the scanning operation at the host institution?
2. Where and when is the description done? Description of the digitized item was universally done by the contributing institution, but the location (at the scanning center or at the contributing institution) and timing (before conversion, during conversion, or after conversion) vary. Answers to the first question — whether contributing staff members are performing the conversion — affect this question.
3. Is contribution of materials to the Ohio Digital Resource Commons required? If the regional scanning center is used to digitize materials (or in the case where the consortium is subsidizing a scanning service to perform the digital conversion), what conditions are put in place for contributing those materials to the central repository.
4. What is the cost structure for use of the regional scanning center? Options range from complete subsidy by consortium (most notably when the CDP funded the equipment at their regional scanning centers) to contributing institutions being charged at cost recovery rates by hosting institutions. There can be various cost structures applied, such as a consortial subsidy for equipment and training with labor supplied by contributing institution or contracted from hosting institution.
5. What training is offered? Topics for training range from optimal use of digitization equipment to digitization project planning to metadata creation standards. The training can be based on group instruction, one-on-one consultation with contributing institutions, or a combination of both.
6. Who will fill the role of “metadata editor”? The need for a collective expert in metadata creation was found in many of the projects. This person is typically charged with training contributing staff on the appropriate use of local metadata conventions, coaching individual staff on particular projects, and reviewing records that will become part of a consortial database.

Report from the CDP

The original climate that generated the interest in scanners was one where institutions did not want to outsource digitization because they didn’t want the materials leaving their direct control. The CDP, on the other hand, did not want institutions to buy cheap scanners that would result in lower-quality scans. The CDP purchased the scanners ($2,500 each, in 1999 dollars) plus desktop workstations and created a training program for the use of the equipment. The center provided the location for the equipment and hands-on assistance with using the equipment; it was incumbent on the staff at the institution with materials to be digitized to perform the scanning themselves. Before using the equipment, those performing the scanning had to attend a CDP “Introduction to Digital Imaging” training session on the proper use and techniques for obtaining high-quality images. Scanning projects that received CDP funding had priority over other users of the equipment, but there was little contention for the equipment at the centers. Descriptive metadata could be keyed at the time of the scan; CDP provided a web-based template (called “DC builder”) or staff could use their own system (an ILS, ContentDM, etc.). Contribution of the associated metadata to the CDP union catalog of metadata — Heritage West — was required for CDP-funded grant projects. Images were locally hosted.

In 2003, the CDP conducted an evaluation of the scan centers in the form of focus groups. They found two different responses. First, institutions on the western slopes of Colorado made much heavier use of their scan centers. These institutions tended to be smaller and/or economically disadvantaged, and the availability of the hardware and software to conduct the scanning operations was more critical. In front range libraries, where institutions tend to be better-funded, the centers were not as heavily used for projects and tended to be used for training and demonstration sites; these participants felt that the greatest value in the CDP came from the professional networking and training opportunities the locations, the grants that the CDP provided and the creation of the best practices and website that brought all this together.

The regional scan centers are not used today. The primary reason is the diffusion of experience within the community that was spurred by the early success of the centers. As funding cycles continued, institutions purchased their own equipment (generally replicating the equipment at the centers) so as avoid the need to transport materials and staff to a regional center for larger projects. The focus of grant funding within CDP also shifted from image-based collections to EAD and sound collections. There is still an “Introduction to Digital Imaging” workshop, but the focus is now on requirements for in-house equipment and/or what to seek from a vendor in an RFP. The imaging workshop is typically taught as part of a three-day workshop series with an “Introduction to Digital Project Management” (storage, preservation, handling socially sensitive materials, how to display them) before and “Introduction to Metadata” (focused on Dublin Core) after. The biggest issue facing the consortium now is oversized scanning; only the very largest university library would have this kind of equipment.

The Colorado model of teaching staff at the institution on the use of the equipment along with the creation of regional scan centers was picked up by several states: North Carolina; Alabama; Kansas; Missouri; and Wyoming (except that regional centers were not practical due to the wide population dispersion). Tennessee is working under a current IMLS grant to build three regional center plus a suite of mobile equipment.

Liz suggests that we should look for ways to support collaborative efforts within the institution with museum and archives on the campus. The Florida Center for Library Automation (FCLA) has a program in place where the local university library is the contact in partnerships with public libraries and local museums.

Leigh noted that in recent years, CDP projects include a “metadata editor” that is hired to look at record quality and work with individual institutions to improve records. Having a metadata editor, someone familiar with the CDP guidelines and the field in general, look at four or five records at the very early stage of a project is critical to the success of the quality of the rest of the project. In a recent project, nearly half of the partners were going to export records out of a local collection management system. It was discovered that the records were not consistent; local implementation/practice of cataloging standards has a higher overall impact than community best practice. Having a local cataloger participate on the team migrating the records from a local system to a central system is key to success.

Mountain West Digital Library

Content is ingested into the MWDL either through digital conversion centers at the regional institutions or through the efforts of the contributing institution. The regional institutions perform digital conversion for contributing institutions at cost-recovery rates. These regional centers use the equipment and staff at the hosting institution, and are very busy at times resulting in difficult choices to balance needs of the host institution with that of requests from other institutions.

The regional centers also conduct on-site training and technical education at contributing institutions about best practice for digital conversion. The on-site program includes a technical evaluation of the equipment to be used to ensure that it can produce conversions that meet the minimum requirements for the MWDL. In the course of this evaluation, staff at contributing institutions are taught some technical aspects of scanning such as the actual DPI scanning capabilities of the hardware versus interpolated resolutions (and why this is important). Staff also receive an introduction to Photoshop for de-skewing and other standard practices. They also are instructed in the Western Standard Metadata Best Practices. This hands-on approach — with the contributing institution’s people, equipment and materials — enables strong connections between the contributing institution and the hosting institution. It makes the contributing institution feel like a part of the larger program. Most contributing institutions with local digital conversion operations will FTP files to the ContentDM server at the regional institution; some institutions contribute materials through the transportation of a portable hard drive.

Each regional hosting center is responsible for the digital preservation of the material on their server. At this point there is no common agreement across the MWDL for standards on digital preservation; this is an area of work to be addressed in the near future by the cooperative.

The cooperative is starting work in several new areas. First is the digital conversion and posting of oral histories from contributing institutions. While it is anticipated that such resource will be highly valued, quick progress on this project is hampered by the same permission problems that face similar projects with relatively old audio. The cooperative also has a state LSTA grant for a Utah institutional repository with a portal connected to the MWDL. The state archives are also beginning a program to post state government documents, including items related to the Olympic Games held in Utah. The hands-on approach to training staff at contributing institutions is very labor-intensive and uneven across the project participants. MWDL is in the process of hiring a program director, and a component of that job description is to provide this kind of training across the project.

Ohio Memory Project (Ohio Historical Society)

OHS staff will work with contributing institutions on a one-on-one basis as well as conduct workshops on introduction to scanning. Many of the participants are from contributing institutions that have had staff changes and the new staff want to know how to use the equipment purchased during the grant-funded phase of the project. There is also a desire for more advanced training, such as Photoshop basics.

OHS staff recognize that a compromise is needed between institutional capabilities for scanning and the very best practices in the field. They have found it hard to establish and mandate an absolute standard for the parameters and quality of digital scans. Institutions that scan their own materials are responsible for their own storage and preservation.

At the meeting we will be sharing observations and experiences with JPEG 2000 for access and preservation of still and moving pictures as well as discussing ideas for advocacy and spreading information. Membership in LITA is not required to attend the meeting. Get this meeting as an iCal file suitable for importing into most calendar programs.

38.9077° by -77.0353°

The text was modified to remove a link to http://j2karclib.info/j2kig on January 19th, 2011.

I’m looking for information about the formation and management of regional digitization centers for one of the OhioLINK strategic task forces. For our purposes, a “regional digitization center” is a place that has the hardware, software, and human expertise to convert a variety of media to digital form. (We’re primarily looking at small format imaging, but could also include broadside imaging, audio capture, and video transformation.) There is plenty of information to be found about the services that centers provide and even more evidence of regional groups wanting to create these centers, but precious little about the operation of the centers themselves. (As in zilch in professional literature searches, and only a few hits via general web searching.) The kinds of things I’m looking for are:

• Operational structures, ranging from staff at the center that do the actual digitization to centers that just provide equipment and the organization wanting the digitized materials providing the staffing.
• Cost structures for initial center development and ongoing support.
• Project plans for building and promoting regional digitization centers.

Here’s what I’ve found so far. There is a really good message from Liz Bishoff from the time she was the Executive Director of the Colorado Digitization Program. There is also this bit from an article Liz Bishoff wrote for First Monday:

To assure that the institutions had access to equipment that supported these standards, the CDP established five regional scan centers. These centers provide the Colorado institutions with relatively easy access to scanning equipment, assistance by trained staff in scanning, and access to the union catalog and local databases via the Web. Each institution has to do their own scanning. Training sessions on scanning and metadata are being conducted throughout the spring and summer, 2000 at these regional scan centers. It is hoped that the combination of consulting on scanning, training, and quality equipment will result in a consistent quality image, as well as developing expertise at the local institution level.¹

The same themes are repeated in an interview from the NINCH Guide to Good Practice. Beyond the CDP project, though, the findable information drops off quickly. I’ve found that the Making of Modern Michigan project has spawned quite a number of regional centers, as have other efforts. I’m going to get in touch with folks in Colorado and Michigan, but in the meantime if you know of something I’ve missed (or you run one of these kinds of centers yourself) please let me know.

The text was modified to remove a link to http://lists.mdch.org/public/digistates/2003-September/000020.html on January 20th, 2011.

Footnotes

1. Bishoff, L. (2000). Interoperability and standards in a museum/library collaborative. First Monday, 5(6). Retrieved May 18, 2007, from http://www.firstmonday.org/issues/issue5_6/bishoff/.

This posting used to have the tag “– Except for Grayscale?” appended to the end of the title. That is no longer needed; see the bottom of the post for an explanation. We have been implementing University of Michigan’s DLXS software, and DLXS uses JPEG2000 for its image masters. We have been investigating reports of perceived changes in images in the conversion from our old media server to DLXS, and along the way I discovered an important fact: the default parameters for two popular JPEG2000 codecs results in an irreversible transformation. Here is how to address that.

Testing For Equivalence

• On a pixel-by-pixel basis, at high magnification, we looked for differences in the RGB and CMYK values between the source TIFF and the converted JPEG2000 image.
• Comparison by copying and pasting the JP2 on top of the TIF image and selecting “Difference” blending mode between the layers. We then look at the histogram of the resulting image. It should be all black, which shows as a black bar on the far left of the histogram view with the mean, median and standard deviation values all exactly 0.
• Using “Images > Calculations…” with 100% opacity difference blending between source images (the TIFF and the JP2) with the results put into a new document shows in a completely black image. (This is likely equivalent to the test above, but we do it just to be sure).

Another test uses geoimgcmp, which is part of GeoJasPer version 1.3.2. This command should return “0″:

geoimgcmp -f source.tif -F destination.jp2 -m rmse

Jasper via ImageMagick

convert source.tif -o destination.jp2

I ran though the tests, though, and it would appear Jasper/ImageMagick is not using the reversible (integer) wavelet transform.

Kakadu

kdu_compress -i source.tif -o destination.jp2

A colleague did offer some help in the form of parameters that he uses to achieve truly lossless compression:

kdu_compress -i source.tif -o destination.jp2 \
       Creversible=yes -rate -,1,0.5,0.25 Clevels=5

The parameters mean this (from the Kakadu usage documentation):

Creversible=yes

Reversible compression?

-rate -,1,0.5,0.25

One or more bit-rates, expressed in terms of the ratio between the total number of compressed bits (including headers) and the product of the largest horizontal and vertical image component dimensions. A dash, “-”, may be used in place of the first bit-rate in the list to indicate that the final quality layer should include all compressed bits. Specifying a very large rate target is fundamentally different to using the dash, “-”, because the former approach may cause the incremental rate allocator to discard terminal coding passes which do not lie on the rate-distortion convex hull. This means that reversible compression might not yield a truly lossless representation if you specify `-rate’ without a dash for the first rate target, no matter how large the largest rate target is.

Clevels=5

Number of wavelet decomposition levels, or stages.

Note that this implies this important default as well.

Corder=LRCP

Default progression order. The four character identifiers have the following interpretation: L=layer; R=resolution; C=component; P=position. The first character in the identifier refers to the index which progresses most slowly, while the last refers to the index which progresses most quickly.

Conclusions

1. Although one might expect the default options for image conversion programs to be lossless, ImageMagick’s ‘convert’ and Kakadu’s ‘kdu_compress’ commands do result in lossy transformations.
2. For our sample images, using the Kakadu command line options “Creversible=yes -rate -,1,0.5,0.25 Clevels=5” do appear to result in lossless transformations for source TIFF images.

Thanks go out to Rob Buckley, Ron Murray, Kevin DeVorsey, Greg Coats, and David Taubman for their help in figuring this out.

4-May-2007 Update

In response to the question of the lossy settings as a default, Dr. Taubman also notes “that quality is somewhat better (particularly at reduced resolutions) when viewing lossy compressed images using the irreversible options rather than the reversible.” There are reasons for this, primarily due with what I understand as the elimination of image signal noise through through the act of lossly compression, but they are too complicated to address in this already-too-large correction text.

The text was modified to update a link from http://wordnet.princeton.edu/perl/webwn?s=red+herring to http://wordnetweb.princeton.edu/perl/webwn?o2=&o0=1&o7=&o5=&o1=1&o6=&o4=&o3=&s=red+herring&i=1&h=1000#c on January 20th, 2011.