TIFF Image Tag Problems

The TIFF specification began as a way to accommodate scanner manufacturers.

The Tagged Image File Format originated with Aldus Corporation in 1986 to acquire, manipulate and store data from scanners used to digitize printed material and display it on a computer. TIFF files use logical structures called fields to characterize the individual components and attributes of image data. Each field consists of a pair of numbers: a tag and its value. To display TIFF files properly, these tags must be recorded correctly by the software that creates them and read correctly by the application that opens them.

TIFF Versions

Aldus Corporation, and later Adobe Systems, issued revisions to the TIFF specification to enable it to support new image features. For example, the earliest version of the TIFF format incorporated no support for color images. The format also gained support for internal image-data compression, enabling it to produce smaller files without data loss. Despite the developers' best efforts, however, some applications experience compatibility problems when they try to display older-version TIFFs, just as some older applications struggle to read newer-version files.

File Errors

If a TIFF file stores one of its tags or tag values incorrectly, the resulting file may be difficult, or even impossible, to read. Poorly written or damaged software can write badly formed files. Even well-written software can create bad output if its attempts to save a file are interrupted by power fluctuations or equipment malfunctions. Well-formed data stored on a damaged hard drive or removable disc can be unreadable because of data corruption. These errors can cause tag-related problems when an application tries to read a damaged file.

Private Tags

The TIFF specification allows individual organizations and companies to create private fields to store information significant to their workflow but irrelevant outside of it. The file format includes a range of tag numbers designed for private use in files that don't reach the general public. Creating a tag for general use requires requesting a tag number explicitly for use with that specific data structure. Poorly designed or improperly numbered tags can cause file-reading errors.

Considerations

TIFF files appear in broad usage within various fields, including the graphic arts, medical imagery and archival applications. In some cases, file structures that incorporate specialized functions start out as TIFF documents, and gain new file extensions to reflect their inclusion of large amounts of privately formatted information. These branches of the TIFF specification exist to support specialized needs without creating files that are incompatible with mainstream image-editing software. Attempting to read these documents by changing their file extensions to TIFF may succeed, if the file structures remain compatible with mass-market software, or may fail because the software cannot read their special tags.

References

• Adobe Systems: TIFF Revision 6.0
• Molecular Dynamics: GEL Image File Format
• Helios Technical Documentation: ICC Profile Tagging Specifications
• IBM: Problem With Reverse Video TIFF Images From IWPM for Windows NT
• ESRI Knowledge Base: Problem: TIFF Image May Display Slowly If Planarconfiguration Tag Is 2
• AWARE Systems: Intergraph's Private TIFF Tags

Resources

• FileFormat.Info: TIFF File Format Summary