Aperio has created their own format called BigTIFF and neatly offering the format into the public domain. To showcase the power of BigTIFF image resolution, Aperio has releaseed the first terapixel image. The image shows 225 pathology slides of breast tissue which can be viewed here.
An overview and other information is available here:
There are more technical details, but at the highest level the BigTIFF changes made to libtiff were quite simple. The TIFF file format internally uses 32-bit byte offsets. The largest offset which can be represented is 232 = 4GB, making that the upper limit of the file size which could be supported by the design. The BigTIFF modifications to libtiff consisted primarily of changing all internal byte offsets to 64-bits. A key goal was to maintain backward compatibility with existing applications and files to the largest extent possible.
BigTIFF files have a ".tif" or ".tiff" file extension just like ordinary TIFF files. A new version in the file header prevents programs which have not linked with the BigTIFF version of libtiff from processing BigTIFF files. The library has been modified so that programs writing TIFF files do not need to know or care when they reach a 4GB data size. The file format will smoothly change from a standard TIFF file (compatible with all existing programs) to a BigTIFF file (compatible with all programs linked with a new version of the libtiff library). Similarly, programs reading TIFF files do not need to know or care whether a file is a standard TIFF file or a BigTIFF file.
The basic BigTIFF design was first proposed in 2004 and refined in this discussion on the Aware Systems mailing list. Contributors to the design discussion included Lynn Quam, Frank Warmerdam, Chris Cox, Rob Tillaart, Dan Smith, Bob Freisenhahn, Andrey Kiselev, Phillip Crews, and Gerben Vos. We thank all those who came before us for creating libtiff and designing the BigTIFF enhancements.
These changes were made by Ole Eichhorn of Aperio Technologies and are donated to the public domain, in gratitude to Sam Leffler, Silicon Graphics, Joris Van Damme, Aware Systems, Frank Warmerdam, Andrey Kisley, Mike Welles, and all who have worked on libtiff over the years to provide such a great tool. These changes are published on an "as is" basis and neither Ole Eichhorn nor Aperio Technologies make any warranty as to their fitness for any intended use.
