1d218770cSJoris Van Damme<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2d218770cSJoris Van Damme<html lang="en"> 3d218770cSJoris Van Damme<head> 4d218770cSJoris Van Damme <title>Proposal to Implement BigTIFF Support in LibTiff</title> 5d218770cSJoris Van Damme</head> 6d218770cSJoris Van Damme<body> 7d218770cSJoris Van Damme <h1>Proposal to Implement BigTIFF Support in LibTiff</h1> 88a5381a0SJoris Van Damme <p><b>NEWS:</b> We have located all four required sponsors. There are no more 9*7a17af90SJoris Van Damme open slots. We will issue appropriate press release shortly.</p> 10d218770cSJoris Van Damme <h2>0. Summary</h2> 11d218770cSJoris Van Damme <p>BigTIFF logically extends the original TIFF file format (referred to as 12d218770cSJoris Van Damme 'ClassicTIFF' from this point on), breaking the 4 gigabyte boundary, in theory 13d218770cSJoris Van Damme allowing files up to 18,000 petabytes in size. The BigTIFF specification is the 14d218770cSJoris Van Damme result of work by a variety of parties on the LibTiff mailing list, including 15d218770cSJoris Van Damme the current LibTiff maintainers, Joris Van Damme and Adobe staff. The BigTIFF 16d218770cSJoris Van Damme specification has not yet been officially approved by the TIFF specification 17d218770cSJoris Van Damme owner (Adobe) but implementation within LibTiff could accelerate that 18d218770cSJoris Van Damme process.</p> 19d218770cSJoris Van Damme <p>For more information on the BigTIFF file format, we recommend 20d218770cSJoris Van Damme <a href="http://www.awaresystems.be/imaging/tiff/bigtiff.html">AWare Systems' 21d218770cSJoris Van Damme BigTIFF page.</a></p> 22d218770cSJoris Van Damme <p>BigTIFF is expected to be especially useful for people and vendors that are 23d218770cSJoris Van Damme confronted with unusually large images, and still seek to use an open, simple, 24d218770cSJoris Van Damme and extendable format. This requirement is frequently seen in the geospatial 25d218770cSJoris Van Damme field, but also affects large format scanners, medical imaging and other 26d218770cSJoris Van Damme fields.</p> 27d218770cSJoris Van Damme <h2>1. Sponsoring</h2> 28d218770cSJoris Van Damme <p>It is planned that LibTiff 4.0, the BigTIFF upgrade to LibTiff, would start 29d218770cSJoris Van Damme March 1, 2007. A preliminary version (LibTiff 4.0alpha1) will be operational by 30d218770cSJoris Van Damme June 15, 2007. Testing and final release improvements for LibTiff 4.0 will be 31d218770cSJoris Van Damme completed by July 30, 2007.</p> 32d218770cSJoris Van Damme <p>The LibTiff BigTIFF upgrade team is seeking USD 24,000 from four sponsors (USD 33d218770cSJoris Van Damme 6,000 each) to fund the project. Sponsorship payment will be invoiced upon 34d218770cSJoris Van Damme delivery of the LibTiff 4.0alpha1 release (on or before June 15) with a 30 day 35d218770cSJoris Van Damme payable, giving time for some technical review.</p> 36d218770cSJoris Van Damme <p>In addition to the benefits of open interchange of BigTIFF data that comes from 37d218770cSJoris Van Damme support in a public and free open source codec, sponsors will be given proper 38d218770cSJoris Van Damme public acknowledgment. During development, they will be mentioned in the 39d218770cSJoris Van Damme appropriate sections of the LibTiff and AWare Systems site.</p> 40d218770cSJoris Van Damme <p>When LibTiff 4.0 with BigTIFF support is released, they will additionally 41d218770cSJoris Van Damme receive public acknowledgment in a formal press release, distributed widely to 42d218770cSJoris Van Damme news venues in the imaging and geospatial industries.</p> 43d218770cSJoris Van Damme <p>A 'migration guide' document or any functional equivalent thereof will be 44d218770cSJoris Van Damme included in the standard free distribution, but sponsors will additionally 45d218770cSJoris Van Damme receive up to 20 hours of consulting and support on any BigTIFF migration issues 46d218770cSJoris Van Damme that they may be facing, and/or any additional related requests they may have.</p> 47d218770cSJoris Van Damme <h2>2. Development and Testing</h2> 48d218770cSJoris Van Damme <p>The work will primarily be done by Joris Van Damme on behalf of his company 49d218770cSJoris Van Damme AWare Systems. Joris was closely involved in the drafting of the BigTIFF file 50d218770cSJoris Van Damme format proposal, and has also developed the proprietary AWare Systems TIFF 51d218770cSJoris Van Damme codec that already supports BigTIFF. Joris Van Damme has a deep understanding 52d218770cSJoris Van Damme of the TIFF format, and has been acting as a LibTiff co-maintainer for over a 53d218770cSJoris Van Damme year, contributing the upgraded OJPEG codec as well as several other 54d218770cSJoris Van Damme improvements.</p> 55d218770cSJoris Van Damme <p>Joris and AWare Systems have agreed to crosstest their proprietary codec and 56d218770cSJoris Van Damme LibTiff's support for BigTIFF extensively. Joris will also extend the test image 57d218770cSJoris Van Damme library included with LibTiff, with a number of varying BigTIFF test files. 58d218770cSJoris Van Damme These files will primarily include test files with issues that relate closely 59d218770cSJoris Van Damme to the BigTIFF file format and the difference with ClassicTIFF. For instance, 60d218770cSJoris Van Damme in BigTIFF the datatypes TIFF_LONG, TIFF_LONG8, TIFF_IFD and TIFF_IFD8 are all 61d218770cSJoris Van Damme valid for tags pointing to additional IFDs, and thus files will be included to 62d218770cSJoris Van Damme illustrate and enable testing all of these. Additionally, Joris will build a 63d218770cSJoris Van Damme tool to enable creating test files that exceed 4 gigabyte, as these can of 64d218770cSJoris Van Damme course not be included in the test suite in a more direct manner, and a tool to 65d218770cSJoris Van Damme convert files from ClassicTIFF to BigTIFF, as well as the other way around for 66d218770cSJoris Van Damme source BigTIFF files that do not exceed 4 gigabyte in size.</p> 67d218770cSJoris Van Damme <p>Frank Warmerdam has also agreed to be involved in a consulting and validation 68d218770cSJoris Van Damme role. Frank has been LibTiff's primary maintainer since approximately the year 69d218770cSJoris Van Damme 2000, develops large-image exploitation software for the geospatial industry 70d218770cSJoris Van Damme (GDAL) and is currently President of the Open Source Geospatial Foundation 71d218770cSJoris Van Damme (OSGeo). Frank will also be ensuring that BigTIFF improvements are made 72d218770cSJoris Van Damme accessible to all users of the GDAL library.</p> 73d218770cSJoris Van Damme <h2>3. Implementation Strategy</h2> 74d218770cSJoris Van Damme <p>Many people who have a need for BigTIFF, use LibTiff already. We thus plan to 75d218770cSJoris Van Damme support BigTIFF in LibTiff, applying a minimum change strategy much like the 76d218770cSJoris Van Damme one that was applied in the creation of the new file format in the first 77d218770cSJoris Van Damme place.</p> 78d218770cSJoris Van Damme <p>To support BigTIFF, we will use a 64bit integer datatype. It is anticipated 79d218770cSJoris Van Damme that some older platforms will not be able to comply with this need, and for 80d218770cSJoris Van Damme that reason we will encapsulate all required changes inside a conditional 81d218770cSJoris Van Damme compilation switch.</p> 82d218770cSJoris Van Damme <p>While it is anticipated that there will be ABI (application binary interface) 83d218770cSJoris Van Damme changes as part of a BigTIFF support upgrade to LibTiff, and possibly some 84d218770cSJoris Van Damme more to support other major upgrades to LibTiff, the plan is such that 85d218770cSJoris Van Damme the source level API will remain compatible for most LibTiff applications. 86d218770cSJoris Van Damme Applications using specialized interfaces may require some minor source code 87d218770cSJoris Van Damme changes, but we will provide backwards compatibility to support the majority 88d218770cSJoris Van Damme of existing application level code.</p> 89d218770cSJoris Van Damme <p>The resulting LibTiff version would transparently support reading traditional 90d218770cSJoris Van Damme 32bit ClassicTIFF files, and 64bit BigTIFF files, as well as writing either 91d218770cSJoris Van Damme ClassicTIFF or BigTIFF files based on a flag in the TIFFOpen/TIFFClientOpen call.</p> 92d218770cSJoris Van Damme <h2>4. Intellectual Property and Licensing</h2> 93d218770cSJoris Van Damme <p>The licensing agreement of LibTiff will remain unchanged.</p> 94d218770cSJoris Van Damme <h2>5. Contact information</h2> 95d218770cSJoris Van Damme <p>Please contact <a href="mailto:[email protected]">Frank Warmerdam</a> and/or 96d218770cSJoris Van Damme <a href="mailto:[email protected]">Joris Van Damme</a> for more information 97d218770cSJoris Van Damme on sponsorship agreements.</p> 98d218770cSJoris Van Damme</body> 99d218770cSJoris Van Damme</html>