TIFF (Tagged Image
File Format)
Introduction
TIFF (Tagged Image File Format) is one of the most popular and flexible of the current public domain raster file formats.
TIFF was developed by Aldus and Microsoft Corporation. The specification was owned by Aldus, which in turn merged with Adobe Systems. Consequently, Adobe Systems now holds the Copyright for the TIFF specification.
Strengths
TIFF is primarily designed for raster data interchange. TIFF's main strengths are a highly flexible and platform-independent format that is supported by numerous image-processing applications. Since developers of printers, scanners and monitors designed it, it has a very rich space of information elements for colorimetry calibration, gamut tables, etc. Such information is also very useful for remote sensing and multi-spectral applications.
Another feature of TIFF that is also useful is the ability to decompose an image by tile rather than scan lines. This permits much more efficient access to very large imagery which has been compressed (since one does not have to decompress an entire
scan line).
Theoretically, TIFF can support imagery with multiple bands (up to 64K bands), arbitrary number of bits per pixel, data cubes, and multiple images per file, including thumbnail sub-sampled images.
Color spaces supported include
1. Grayscale
2. Pseudo-color (any size)
3. RGB
4. YCbCr
5. CMYK
6. CIELab
Compression types include
1. Raw uncompressed,
2. PackBits
3. Lempel-Ziv-Welch (LZW)
4. CCITT Fax 3 & 4
5. JPEG (see below)
Pixel formats supported include:
1. 1-64 bit integer, signed or unsigned
2. 32 or 64 bit IEEE floating point
Limitations
There are no provisions in TIFF for storing vector graphics, text annotation, etc (although such items could be easily constructed using TIFF extensions). As such, if this is a requirement you would be better off with a format with broader scope, such as PostScript,
CGM, or PICT. TIFF is based on file-offsets, so that it is not easily
"streamable" in the way JPEG JFIF streams are.
A common complaint of TIFF is rooted in its flexibility. For example the TIFF format permits both MSB ("Motorola") and LSB ("Intel") byte order data to be stored, with a header item indicating which order is used. There are old, poorly written TIFF programs on the PC that rebelled against this and assumed that all TIFF files are Intel byte order. It is very easy to write a TIFF-writer, but very difficult to write a fully TIFF compliant reader.
TIFF uses a 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). However, this is 4G of compressed data, and so if the compression ratio is high enough, theoretically a TIFF image could be much larger.
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