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Tagged Image File Format

Tagged Image File Format

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Encyclopedia
TIFF is a file format for storing images
Raster graphics
In computer graphics, a raster graphics image, or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium...

, popular among graphic artists, the publishing industry, and both amateur and professional photographers in general. As of 2009, it is under the control of Adobe Systems
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...

. Originally created by the company Aldus
Aldus
Aldus Corporation, named after the 15th-century Venetian printer Aldus Manutius, was the inventor of the groundbreaking PageMaker software, a program that is generally credited with creating the desktop publishing field. The company was founded by Jeremy Jaech, Mark Sundstrom, Mike Templeman,...

 for use with what was then called "desktop publishing
Desktop publishing
Desktop publishing is the creation of documents using page layout software on a personal computer.The term has been used for publishing at all levels, from small-circulation documents such as local newsletters to books, magazines and newspapers...

", the TIFF format is widely supported by image-manipulation applications, by publishing and page layout applications, by scanning
Image scanner
In computing, an image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass...

, faxing
Fax
Fax , sometimes called telecopying, is the telephonic transmission of scanned printed material , normally to a telephone number connected to a printer or other output device...

, word processing
Word processor
A word processor is a computer application used for the production of any sort of printable material....

, optical character recognition
Optical character recognition
Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping...

 and other applications. Adobe Systems, which acquired Aldus, now holds the copyright to the TIFF specification. TIFF has not had a major update since 1992, though several Aldus/Adobe technical notes have been published with minor extensions to the format, and several specifications, including TIFF/EP
Tag Image File Format / Electronic Photography
"Tag Image File Format / Electronic Photography" is a digital image file format standard – ISO 12234-2, titled "Electronic still-picture imaging – Removable memory – Part 2: TIFF/EP image data format"...

 (ISO 12234-2), TIFF/IT (ISO 12639), TIFF-F (RFC 2306) and TIFF-FX (RFC 3949) have been based on the TIFF 6.0 specification.

History


The phrases "Tagged Image File Format" and "Tag Image File Format" were used as the subtitle to some early versions of the TIFF specification; the 1992 specification, TIFF 6.0, does not use either subtitle phrase, but is simply "TIFF".

TIFF was originally created as an attempt to get desktop scanner
Image scanner
In computing, an image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass...

 vendors of the mid-1980s to agree on a common scanned image file format, rather than have each company promote its own proprietary format. In the beginning, TIFF was only a binary image
Binary image
A binary image is a digital image that has only two possible values for each pixel. Typically the two colors used for a binary image are black and white though any two colors can be used. The color used for the object in the image is the foreground color while the rest of the image is the...

 format (only two possible values for each pixel), because that was all that desktop scanners could handle. As scanners became more powerful, and as desktop computer disk space became more plentiful, TIFF grew to accommodate grayscale
Grayscale
In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information...

 images, then color images. Today, TIFF is a popular format for high color-depth
Color depth
In computer graphics, color depth or bit depth is the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. This concept is also known as bits per pixel , particularly when specified along with the number of bits used...

 images, along with JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....

 and PNG.

The first version of the TIFF specification was published by Aldus Corporation in the autumn of 1986 after two major earlier draft releases. It can be labeled as Revision 3.0. It was published after a series of meetings with various scanner manufacturers and software developers. In April 1987 Revision 4.0 was released and it contained mostly minor enhancements. In October 1988 Revision 5.0 was released and it added support for palette color images and LZW compression.

Flexible options


TIFF is a flexible, adaptable file format for handling images and data within a single file, by including the header tags (size, definition, image-data arrangement, applied image compression
Image compression
The objective of image compression is to reduce irrelevance and redundancy of the image data in order to be able to store or transmit data in an efficient form.- Lossy and lossless compression :...

) defining the image's geometry. For example, a TIFF file can be a container holding compressed (lossy) JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....

 and (lossless) PackBits
PackBits
PackBits is a fast, simple lossless compression scheme for run-length encoding of data.Apple introduced the PackBits format with the release of MacPaint on the Macintosh computer. This compression scheme is one of the types of compression that can be used in TIFF-files...

 compressed images. A TIFF file also can include a vector-based clipping path
Clipping path
A clipping path is a closed vector path, or shape, used to cut out a 2D image in image editing software. Anything inside the path will be included after the clipping path is applied; anything outside the path will be omitted from the output...

 (outlines, croppings, image frames). The ability to store image data in a lossless
Lossless data compression
Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. The term lossless is in contrast to lossy data compression, which only allows an approximation of the original data to be reconstructed, in exchange...

 format makes a TIFF file a useful image archive, because, unlike standard JPEG files, a TIFF file using lossless compression (or none) may be edited and re-saved without losing image quality. This is not the case when using the TIFF as a container holding compressed JPEG. Other TIFF options are layers
Layers (digital image editing)
Layers are used in digital image editing to separate different elements of an image. A layer can be compared to a transparency on which imaging effects or images are applied and placed over or under an image...

 and pages.

TIFF offers the option of using LZW compression, a lossless data-compression technique for reducing a file's size. Until 2004, use of this option was limited because the LZW technique was under several patents. However, these patents have expired.

The TIFF 6.0 specification consists of the following parts:
  • Introduction (contains information about TIFF Administration, usage of Private fields and values, etc.)
  • Part 1: Baseline TIFF
  • Part 2: TIFF Extensions
  • Part 3: Appendices

Part 1: Baseline TIFF


When TIFF was introduced, its extensibility provoked compatibility problems. The flexibility in encoding gave rise to the joke that TIFF stands for Thousands of Incompatible File Formats. To avoid these problems, every TIFF reader was required to read Baseline TIFF. The Baseline TIFF does not include layers, or compression with JPEG or LZW.

The Baseline TIFF is formally known as TIFF 6.0, Part 1: Baseline TIFF. The following is an incomplete list of required Baseline TIFF features:

Multiple subfiles


TIFF readers must be prepared for multiple/multi-page images (subfiles) per TIFF file, although they are not required to do anything with images after the first one.

There may be more than one Image File Directory (IFD) in a TIFF file. Each IFD defines a subfile. One potential use of subfiles is to describe related images, such as the pages of a facsimile document. A Baseline TIFF reader is not required to read any IFD beyond the first one.

Compression


Baseline TIFF readers must handle the following three compression schemes:
  • No compression
  • CCITT
    ITU-T
    The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....

     Group 3 1-Dimensional Modified Huffman
    Huffman coding
    In computer science and information theory, Huffman coding is an entropy encoding algorithm used for lossless data compression. The term refers to the use of a variable-length code table for encoding a source symbol where the variable-length code table has been derived in a particular way based on...

     RLE
  • PackBits compression - a form of run-length encoding
    Run-length encoding
    Run-length encoding is a very simple form of data compression in which runs of data are stored as a single data value and count, rather than as the original run...


Image types


Baseline TIFF image types are: bilevel, grayscale, palette-color, and RGB full-color images.

Byte order


Every TIFF begins with a 2-byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...

 indicator of byte order: "II" for little-endian and "MM" for big-endian byte ordering. The next 2 bytes represent the number 42
42 (number)
42 is the natural number immediately following 41 and directly preceding 43. The number has received considerable attention in popular culture as a result of its central appearance in The Hitchhiker's Guide to the Galaxy as the "Answer to the Ultimate Question of Life, the Universe, and...

, selected because this is the binary pattern 101010 and "for its deep philosophical significance".
The 42-reading depends upon the byte order indicated by the 2-byte indicator. All words, double words, etc., in the TIFF file are assumed to be in the indicated byte order. The TIFF 6.0 specification says that compliant TIFF readers must support both byte orders (II and MM); writers may use either.

Other TIFF fields


TIFF readers must be prepared to encounter and ignore private fields not described in the TIFF specification. TIFF readers must not refuse to read a TIFF file if some optional fields do not exist.

Part 2: TIFF Extensions


Many TIFF readers support tags additional to those in Baseline TIFF, but not every reader supports every extension. As a consequence, Baseline TIFF features became the lowest common denominator
Lowest common denominator
In mathematics, the lowest common denominator or least common denominator is the least common multiple of the denominators of a set of vulgar fractions...

 for TIFF format. Baseline TIFF features are extended in TIFF Extensions (defined in the TIFF 6.0 Part 2 specification) but extensions can also be defined in private tags.

The TIFF Extensions are formally known as TIFF 6.0, Part 2: TIFF Extensions. Here are some examples of TIFF extensions defined in TIFF 6.0 specification:
  • CCITT T.4 bi-level encoding
  • CCITT T.6 bi-level encoding
  • LZW Compression scheme
  • JPEG Compression scheme
  • CMYK Images
  • YCbCr Images
  • HalftoneHints
  • Tiled Images
  • CIE L*a*b* Images


Many used TIFF images contain only uncompressed 32-bit CMYK
CMYK color model
The CMYK color model is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key...

 or 24-bit RGB
RGB color model
The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors...

 images.

According to TIFF 6.0 specification (Introduction), all TIFF files using proposed TIFF extensions that are not approved by Adobe as part of Baseline TIFF (typically for specialized uses of TIFF that do not fall within the domain of publishing or general graphics or picture interchange) should be either not called TIFF files or should be marked some way so that they will not be confused with mainstream TIFF files.

Private tags


Developers can apply for a block of "private tags" to enable them to include their own proprietary information inside a TIFF file without causing problems for file interchange. TIFF readers are required to ignore tags that they do not recognize, and a registered developer's private tags are guaranteed not to clash with anyone else's tags or with the standard set of tags defined in the specification.

TIFF Tags numbered 32768 or higher, sometimes called private tags, are reserved for information meaningful only for some organization or for experiments with a new compression scheme within TIFF. Upon request, the TIFF administrator (Adobe) will allocate and register one or more private tags for an organization, to avoid possible conflicts with other organizations. Organizations and developers are discouraged from choosing their own tag numbers, because doing so could cause serious compatibility problems. However, if there is little or no chance that TIFF files will escape a private environment, organizations and developers are encouraged to consider using TIFF tags in the "reusable" 65000-65535 range. There is no need to contact Adobe when using numbers in this range.

Internet Media Type


The image/tiff MIME type (defined in RFC 3302) without an application parameter is used for Baseline TIFF 6.0 files or to indicate that it is not necessary to identify a specific subset of TIFF or TIFF extensions. The optional "application" parameter (Example: Content-type: image/tiff; application=foo) is defined for image/tiff to identify a particular subset of TIFF and TIFF extensions for the encoded image data, if it is known. According to RFC 3302, specific TIFF subsets or TIFF extensions used in the application parameter must be published as an RFC.

TIFF Compression Tag


The TIFF Tag 259 (hex 0x0103) stores the information about the Compression method. The default value is 1 = no compression.

Most of TIFF writers and TIFF readers support only some of existing TIFF compression schemes. Here are some examples of used TIFF compression schemes:
TIFF Compression Tag
Tag value Compression scheme Lossy/lossless Specification Description Type of images Usage and support
1 Uncompressed Lossless TIFF 6.0 Baseline TIFF all
2 CCITT Group 3 1-Dimensional Modified Huffman run length encoding (a.k.a. MH or CCITT 1D) Lossless TIFF 6.0 Baseline TIFF; compression based on ITU-T T.4 black and white
32773 PackBits compression, a.k.a. Macintosh RLE Lossless TIFF 6.0 Baseline TIFF all
3 CCITT T.4 bi-level encoding as specified in section 4, Coding, of ITU-T Recommendation T.4 (a.k.a. CCITT Group 3 fax encoding or CCITT Group 3 2D) Lossless TIFF 6.0 TIFF 6.0 Extensions; compression based on ITU-T T.4 black and white
4 CCITT T.6 bi-level encoding as specified in section 2 of ITU-T Recommendation T.6 (a.k.a. CCITT Group 4 fax encoding) Lossless TIFF 6.0 TIFF 6.0 extensions; compression based on ITU-T T.6 black and white
5 LZW (Lempel-Ziv & Welch algorithm) Lossless TIFF 6.0 TIFF 6.0 Extensions; first defined in TIFF 5 (1988); a patented compression algorithm, but the patents expired in 2003 and 2004 all
6 JPEG ('old-style' JPEG, later overridden in Technote2) Lossy TIFF 6.0 TIFF 6.0 Extensions; first defined in TIFF 6 (1992) continuous-tone
7 JPEG ('new-style' JPEG) Lossy TIFF 6 Technote2 (1995) Technote2 overrides old-style JPEG compression; it is a TIFF 6.0 extension continuous-tone
32946 Deflate (PKZIP-style Deflate encoding) (experimental) Lossless proprietary According to TIFF Specification Supplement 2 it should be considered obsolete but reading is recommended all
8 Deflate ('Adobe-style') Lossless TIFF Specification Supplement 2 (2002) Adobe Photoshop TIFF Technical Notes; it is a TIFF 6.0 extension all
9 JBIG, per ITU-T T.85 Lossless TIFF-FX RFC 2301 (1998), RFC 3949 (2005) black and white
10 JBIG, per ITU-T T.43 Lossless TIFF-FX RFC 2301 (1998), RFC 3949 (2005) black and white
32766 NeXT RLE 2-bit grey scale encoding proprietary
32809 ThunderScan RLE 4-bit encoding proprietary black and white
32895 RasterPadding in CT or MP (Continuous Tone or Monochrome Picture) Lossless TIFF/IT (1998, 2004) ISO 12639
32896 RLE for LW (Line Work) Lossless TIFF/IT (1998, 2004) ISO 12639
32897 RLE for HC (High-resolution Continuous-tone) Lossless TIFF/IT (1998, 2004) ISO 12639
32898 RLE for BL (Binary Line work) Lossless TIFF/IT (1998, 2004) ISO 12639
32947 Kodak DCS proprietary
34661 JBIG LibTiff black and white
34712 JPEG2000 proprietary Intoduced by Leadtools
34713 Nikon NEF Compressed proprietary

BigTIFF


The TIFF file formats use 32-bit offsets, which limits file size to 4 GiB
Gibibyte
The gibibyte is a standards-based binary multiple of the byte, a unit of digital information storage. The gibibyte unit symbol is GiB....

 (4,294,967,296 bytes). BigTIFF is a TIFF variant file format which uses 64-bit offsets and supports much larger files. The BigTIFF file format specification was implemented in 2007 in development releases of LibTIFF
Libtiff
Libtiff is a library for reading and writing Tagged Image File Format files. The set also contains command line tools for processing TIFFs. It is distributed in source code and can be found as binary builds for all kinds of platforms...

 version 4.0, which is still in beta development. Support for BigTIFF file formats by applications is limited.

In document imaging



Adobe holds the copyright on the TIFF specification (aka TIFF 6.0) along with the two supplements that have been published. All of these documents can be found on the Adobe TIFF Resources page. TIFF specification has not been standardized by either ISO or ANSI, but other standards based on TIFF specification were standardized. Various TIFF variations have been used by organizations for numerous years.

TIFF files that strictly use the basic "tag sets" as defined in TIFF 6.0 along with restricting the compression technology to the methods identified in TIFF 6.0 and are adequately tested and verified by multiple sources for all documents being created can be used for storing documents. Commonly seen issues encountered in the content and document management industry associated with the use of TIFF files arise when the structures contain proprietary headers, are not properly documented, and/or contain "wrappers" or other containers around the TIFF datasets, and/or include improper compression technologies, or those compression technologies are not properly implemented.

Variants of the TIFF format can be used within document imaging
Document imaging
Document imaging is an information technology category for systems capable of replicating documents commonly used in business. Document imaging systems can take many forms including microfilm, on demand printers, facsimile machines, copiers, multifunction printers, document scanners, computer...

 and content/document management systems using CCITT
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....

 Group IV 2D compression
Group 4 compression
Group 4 compression, usually abbreviated as G4, is a method of image compression used in Group 4 fax machines, defined in the ITU-T T.6 fax standard. It is only used for monochrome images. G4 compression is also available in the TIFF image file format, as well as in the PDF document format....

 which supports black-and-white
Black-and-white
Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...

 (bitonal, monochrome
Monochrome
Monochrome describes paintings, drawings, design, or photographs in one color or shades of one color. A monochromatic object or image has colors in shades of limited colors or hues. Images using only shades of grey are called grayscale or black-and-white...

) images, among other compression technologies that support color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

. When storage capacity and network bandwidth was a greater issue that commonly seen in today's server environments, high-volume storage scanning, documents were scanned in black and white (not in color or in grayscale) to conserve storage capacity. An average A4
ISO 216
ISO 216 specifies international standard paper sizes used in most countries in the world today. It defines the "A" and "B" series of paper sizes, including A4, the most commonly available size...

 scanning produces 30 kB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

 of data at 200 PPI
Pixels per inch
Pixels per inch or pixel density is a measurement of the resolution of devices in various contexts; typically computer displays, image scanners, and digital camera image sensors....

 (pixels per inch of resolution) and 50 kB of data at 300 PPI; 300 PPI is more common than 200 PPI.

The TIFF format can save multi-page documents to a single TIFF file rather than a series of files for each scanned page. Multi-page support and 2D compression of bitonal images led to TIFF's becoming the widely accepted format for facsimiles, especially on Fax Servers
Fax server
A fax server is a system installed in a local area network server that allows computer users whose computers are attached to the LAN to send and receive fax messages...

.

In scientific imaging


The inclusion of the SampleFormat tag in TIFF 6.0 allows TIFF files to handle advanced pixel data types, including integer images with more than 8 bits per channel and floating point images. This tag made TIFF 6.0 a viable format for scientific image processing where extended precision is required. An example would be the use of TIFF to store images acquired using scientific CCD cameras that provide up to 16 bits per photosite of intensity resolution. Storing a sequence of images in a single TIFF file is also possible, and is allowed under TIFF 6.0, provided the rules for multi-page images are followed.

In many cases TIFF has been superseded by FITS
FITS
Flexible Image Transport System is a digital file format used to store, transmit, and manipulate scientific and other images. FITS is the most commonly used digital file format in astronomy...

 files for scientific applications (for example astronomical data).

TIFF/IT


TIFF/IT is a file format structured to digitally send data for print ready pages that have been created on high-end prepress systems. The TIFF/IT specification (ISO 12639) describes a multiple-file format which can describe a single page per file set. TIFF/IT files are different from common TIFF files and they are not interchangeable.

The goals in developing TIFF/IT were to carry forward the original IT8
IT8
IT8 is a set of American National Standards Institute standards for color communications and control specifications. Formerly governed by the IT8 Committee, IT8 activities were merged with those of the Committee for Graphics Arts Technologies Standards in 1994.-Standards List:The following is a...

 magnetic tape formats into a media independent version. TIFF/IT is based on Adobe TIFF 6.0 specification and both extends TIFF 6 by adding additional tags and restricts it by limiting some tags and the values within tags. Not all valid TIFF/IT images are valid TIFF 6.0 images.

TIFF/IT defines image file formats for encoding colour continuous tone picture images, colour line art images, high resolution continuous tone images, monochrome continuous tone images, binary picture images, binary line art images, screened data, and images of composite final pages.

TIFF/IT files


TIFF/IT consists of a number of different files and it cannot be created or opened by common desktop applications. TIFF/IT-P1 file sets usually consist of the following files:
  • Final Page (FP)
  • Continuous Tone image (CT)
  • Line Work image (LW)
  • High resolution Continuous-tone files (HC - optional)

TIFF/IT also defines the following files:
  • Monochrome continuous-tone Picture images (MP)
  • Binary Picture images (BP)
  • Binary Line-art images (BL)
  • Screened Data (SD)


Some of these data types are partly compatible with the corresponding definitions in the TIFF 6.0 specification. The Final Page (FP) allows the various files needed to define a complete page to be grouped together - it provides a mechanism for creating a package that includes separate image layers (of types CT, LW, etc.) to be combined to create the final printed image. Its use is recommended but not required. There must be at least one subfile in an FP file, but no more than one of each type. It typically contains a CT subfile and an LW subfile.

The primary color space for this standard is CMYK, but also other color spaces and the use of ICC Profiles are supported.

Compression


TIFF/IT makes no provision for compression within the file structure itself, but there are no restrictions. (For example, it is allowed to compress the whole file structure in a ZIP archive.)
LW files use a specific compression scheme known as Run-length encoding for LW (Compression tag value is 32896). HC files also use a specific Run-length encoding for HC (Compression tag value is 32897). The TIFF/IT P1 specs do not allow use of compression within the CT file.

The following is a list of defined TIFF/IT compression schemes:
TIFF/IT compression schemes
File type TIFF/IT conformance TIFF/IT-P1 conformance TIFF/IT-P2 conformance Description
Final Page (FP) 0th IFD field Uncompressed (1), Deflate (8) or PackBits (32773) Uncompressed (1), Deflate (8) or PackBits (32773) Uncompressed (1), Deflate (8) or PackBits (32773)
Continuous Tone (CT) Uncompressed (1), JPEG (7), Deflate (8) or RasterPadding in CT or MP (32895) Uncompressed (1) Uncompressed (1), JPEG (7), Deflate (8)
Line Work (LW) RLE for LW (32896) RLE for LW (32896) RLE for LW (32896)
High resolution Continuous tone (HC) RLE for HC (32897) RLE for HC (32897) RLE for HC (32897)
Monochrome continuous-tone Picture (MP) Uncompressed (1), JPEG (7), Deflate (8) or RasterPadding in CT or MP (32895) Uncompressed (1) Uncompressed (1), JPEG (7), Deflate (8)
Binary Picture images (BP) Uncompressed (1), CCITT T.6 bi-level encoding (4), Deflate (8) Uncompressed (1) Uncompressed (1), CCITT T.6 bi-level encoding (4), Deflate (8)
Binary Line art (BL) RLE for BL (32898) RLE for BL (32898)
Screened Data (SD) Uncompressed (1), CCITT T.6 bi-level encoding (4), Deflate (8) Uncompressed (1), CCITT T.6 bi-level encoding (4), Deflate (8)

Internet Media Type


There is no MIME type defined for TIFF/IT. The image/tiff MIME type should not be used for TIFF/IT files, because TIFF/IT does not conform to Baseline TIFF 6.0 and the widely-deployed TIFF 6.0 readers are not able to read TIFF/IT. The image/tiff MIME type (defined in RFC 3302) without an application parameter is used for Baseline TIFF 6.0 files or to indicate that it is not necessary to identify a specific subset of TIFF or TIFF extensions. The application parameter should be used with the image/tiff to distinguish TIFF extensions or TIFF subsets. According to RFC 3302, specific TIFF subsets or TIFF extensions must be published as an RFC. There is no such an RFC for TIFF/IT. There is also no plan by the ISO committee that oversees TIFF/IT standard to register TIFF/IT with either a parameter to image/tiff or as new separate MIME type.

TIFF/IT P1


The ISO 12639:1998 introduced TIFF/IT-P1 (Profile 1) - a direct subset of the full TIFF/IT standard (previously defined in ANSI IT8.8–1993). This subset was developed on the ground of the mutual realization by both the standards and the software development communities that an implementation of the full TIFF/IT standard by any one vendor was both unlikely (because of its complexity), and unnecessary (because Profile 1 would cover most applications for digital ad delivery). Almost all TIFF/IT files in digital advertising were distributed as TIFF/IT-P1 file sets in 2001. When people talk about TIFF/IT, they usually mean the P1 standard.

Here are some of the restrictions on TIFF/IT-P1 (compared to TIFF/IT):
  • Uses CMYK only (when appropriate)
  • It is pixel interleaved (when appropriate)
  • Has a single choice of image orientation
  • Has a single choice of dot range
  • Restricted compression methods


TIFF/IT-P1 is a simplified conformance level of TIFF/IT and it maximizes the compatibility between Color Electronic Prepress Systems (CEPS) and Desk Top Publishing (DTP) worlds. It provides a clean interface for the proprietary CEPS formats such as the Scitex CT
Scitex CT
Scitex Continuous Tone or Scitex CT is an image file format. It is designed specifically for use on Scitex graphics processing equipment. Its use is supported by numerous graphics suites and desktop publishing packages, such as Adobe Photoshop, Adobe InDesign, and QuarkXPress....

/LW format.

TIFF/IT P2


Because TIFF/IT P1 had a number of limitations, an extended format was developed. The ISO 12639:2004 introduced a new extended conformance level - TIFF/IT-P2 (Profile 2). TIFF/IT-P2 added a number of functions to TIFF/IT-P1 like:
  • CMYK spot colours only (when appropriate)
  • Support for the compression of CT and BP data (JPEG and Deflate)
  • Support for multiple LW and CT files in a single file
  • Support for copydot files through a new file type called SD (Screened Data)
  • There was some effort to create a possibility to concatenate FP, LW, and CT files into a single file called the GF (Group Final) file, but this was not defined in a draft version of ISO 12639:2004.


This format was not widely used.

Private tags


The TIFF/IT specification preserved the TIFF possibility for developers to utilize private tags. The TIFF/IT specification is very precise regarding how these private tags should be treated - they should be parsed, but ignored.

Private tags in the TIFF/IT-P1 specification were originally intended to provide developers with ways to add specific functionality for specific applications. Private tags can be used by developers (e.g. Scitex) to preserve specific printing values or other functionality. Private tags are typically labelled with tag numbers greater than or equal to 32768.

All private tags must be requested from Adobe (the TIFF administrator) and registered.

History


In 1992 the DDAP (Digital Distribution of Advertising for Publication, later Digital Directions in Applications for Production) developed their requirement statement for digital ad delivery. This was presented to ANSI-accredited CGATS (Committee for Graphic Arts Technology Standards) for development of an accredited file format standard for the delivery of digital ads. CGATS reviewed their alternatives for this purpose and TIFF format seemed like the ideal candidate, except for the fact that it could not handle certain required functionalities. CGATS asked Aldus (the TIFF administrator) for a block of their own TIFF private tags in order to implement what eventually became TIFF/IT. For example, the ability to identify the sequence of the colors is handled by tag 34017 - the Color Sequence Tag.

TIFF/IT was created to satisfy the need for a transport-independent method of encoding raster data in the IT8.1,
IT8.2 and IT8.5 standards.

Standards


TIFF/IT was defined in ANSI IT8.8–1993 standard in 1993 and later revised in the International Standard ISO 12639:1998 - Prepress digital data exchange – Tag image file format for image technology (TIFF/IT). The ISO standard replaces ANSI IT8.8–1993. It specifies a media-independent means for prepress electronic data exchange.

The ISO 12639:2004 (Second edition) standard for TIFF/IT superseded the ISO 12639:1998. It was also later extended in ISO 12639:2004 / Amd. 1:2007 - Use of JBIG2-Amd2 compression in TIFF/IT.

See also

  • Comparison of graphics file formats
    Comparison of graphics file formats
    -General:Ownership of the format and related information.-Technical details:...

  • DNG
    Digital Negative (file format)
    Digital Negative is an open raw image format owned by Adobe used for digital photography. It was launched on September 27, 2004. The launch was accompanied by the first version of the DNG specification, plus various products including a free of charge DNG Converter utility...

  • GeoTIFF
    GeoTIFF
    GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for...

  • Image file formats
    Image file formats
    Image file formats are standardized means of organizing and storing digital images. Image files are composed of either pixels, vector data, or a combination of the two. Whatever the format, the files are rasterized to pixels when displayed on most graphic displays...

  • STDU Viewer
    STDU Viewer
    STDU Viewer is a compact viewer for PDF, WWF, DjVu, Comic Book Archive , FB2, XPS, TCR, multi-page TIFF, TXT, PalmDoc , EMF, WMF, BMP, GIF, JPG, JPEG, PNG, PSD, PCX, DCX files...

  • Windows Picture and Fax Viewer
    Windows Picture and Fax Viewer
    Windows Photo Viewer is an image viewer developed by Microsoft that is included with Windows 7. It was also included with Windows XP and Windows Server 2003 under the name of Windows Picture and Fax Viewer. It was temporarily replaced with Windows Photo Gallery in Windows Vista, but has been...

  • T.37 (ITU-T recommendation)

External links

  • Adobe TIFF Resources page: Adobe links to the specification and main TIFF resources
  • LibTIFF Home Page: Widely used library used for reading and writing TIFF files as well as TIFF file processing command line tools
  • TIFF File Format FAQ and TIFF Tag Reference: Everything you always wanted to know about the TIFF File Format but were afraid to ask
  • TIFF description at Digital Preservation (The Library of Congress)
  • TIFF Revision 4.0: Specification for revision 4.0, in HTML (warning: for historical purposes only, the TIFF 6.0 spec contains the full 4.0 revision)
  • TIFF Revision 5.0: Specification for revision 5.0, in HTML (warning: for historical purposes only, the TIFF 6.0 spec contains the full 5.0 revision)
  • TIFF Revision 6.0: Specification for revision 6.0, in PDF (warning: there is an outdated and flawed section (jpeg compression), corrected in supplements, and there are additions to this PDF too – for the full specification, see the Adobe TIFF Resources page)
  • RFC 3302 - image/tiff, RFC 3949 and RFC 3950 - image/tiff-fx, RFC 2306 - Tag Image File Format (TIFF) - F Profile for Facsimile, RFC 1314 - legacy exchange of images in the Internet
  • AlternaTIFF - Free in-browser TIFF viewer