Tagged Image File Format (abbreviated TIFF) is a rasterfile format for digital images, created by Aldus for use with PostScript printing and now controlled by Adobe. TIFF has become the de facto standard graphics format for high color depth (32-bit) graphics, is widely used in image manipulation applications such as Photoshop, DTP, and scanning, and can be directly manipulated by PostScript.
TIFF includes a number of options that can be used to include all sorts of image formats in the file; this is the purpose of the "tags" that are included in the header. Many of these tags indicate the simple geometry of the image, like its size, but others define how the data is arranged and various compression options. For instance, TIFF can be used as a container for JPEG or RLE (run-length encoding) compressed images, and in this respect is completely universal.
However, when TIFF was first introduced, programmers were unwilling to invest the time to support all of the options. As a result the lowest common denominator soon became "the" TIFF, and even today the vast majority of TIFF files, and the code that reads them, are based on a simple 32-bit uncompressed image.
Every TIFF file begins with a 2-byte indicator of byte order: "II" for little endian and "MM" for big endian byte ordering. The following 2 bytes represent the number 42. The reading of 42 is dependent on the byte order indicated in the first 2 bytes. The entire file is read based on the indicated byte order.
External links
Adobe TIFF Resources page (http://partners.adobe.com/public/developer/tiff/index.html): Adobe linking to the specification and main TIFF resources
LibTIFF Home Page (http://www.remotesensing.org/libtiff/): the most widely used library used for reading and writing TIFF files
TIFF File Format FAQ and Tag Reference (http://www.awaresystems.be/imaging/tiff.html): everything you always wanted to know about the TIFF File Format but were afraid to ask
As a result the lowest common denominator soon became "the" TIFF, and even today the vast majority of TIFF files, and the code that reads them, are based on a simple 32-bit uncompressed image.
TIFF has an option to use LZW compression, a loss-free technique of reducing file size, however this technique is covered under several patents in different jurisdictions.
TIFF uses 4-byte integer file offsets to store image data, with the consequence that a TIFF file cannot have more than 4 Gigabytes of raster data (and some files have begun to approach this boundary).
TIFF was developed by Aldus and Microsoft Corp, and the specification was owned by Aldus, which in turn merged with Adobe Systems, Incorporated.
TIFF is a very extensible format, and there are a number of efforts to extend TIFF for specific applications by registering new tags with Adobe.
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