Sustainability of Digital Formats: Planning for Library of Congress Collections
Sustainability of Digital Formats: Planning for Library of Congress Collections |
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | ISO 12369. Graphic Technology -- Prepress digital data exchange -- Tag image file format for image technology (TIFF/IT) (formal name); TIFF/IT (common name) |
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| Description | ISO 12639:2004 specifies a media-independent means for prepress electronic data exchange using a tag image file format (TIFF). It defines image file formats for encoding color continuous-tone picture images (CT), color line-art images (LW), high-resolution continuous-tone images (HC), monochrome continuous-tone picture images (MP), binary picture images (BP), binary line-art images (BL), screened data (SD), and images of composite final pages (FP). The FP subtype 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. |
| Production phase | Intended as a middle-state format, for transmission of prepared images (such as advertisements) for integration into print publications (such as magazines). |
| Relationship to other formats | |
| Subtype of | TIFF_6, TIFF, Revision 6.0 and earlier. See notes below. |
| Has subtype | Profiles P1 and P2, not documented separately. |
| Has subtype | CT (continuous tone picture data), LW (color line art data), HC (high-resolution continuous tone image data), MP (monochrome picture image data), BP (binary picture image data), BL (binary line art image data), and SD (screened data). Not documented separately. |
| Has subtype | FP (final page data). Not documented separately. |
| LC experience or existing holdings | None. |
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| LC preference | TBD |
| Disclosure | Open standard. Initially documented in ANSI standard IT8.8. As ISO 12369 (based on IT8.8:1993), it has been maintained and extended by ISO/TC130. |
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| Documentation | ISO 12369:2004. Graphic Technology -- Prepress digital data exchange -- Tag image file format for image technology (TIFF/IT). Supersedes ISO 12369:1998. |
| Adoption |
Many magazines and journals require that all advertising materials be submitted as TIFF/IT (usually constrained to the P1 profile) or PDF/X files. As of Summer 2005, it appeared that PDF/X was typically preferred over TIFF/IT and the predominance of PDF/X has continued. PDF/X has an important advantage over TIFF/IT in that TIFF/IT is completely raster based (so TIFF/IT files tend to be quite large) whereas PDF/X files can be both vector based and raster based. Hence PDF/X files are often smaller than TIFF/IT files. Also, see notes below. |
| Licensing and patents | None. |
| Transparency | TBD |
| Self-documentation | See TIFF_6 and Tags for TIFF and Related Specifications. |
| External dependencies | None |
| Technical protection considerations | None |
| Still Image | |
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| Normal rendering | Excellent in professional tools. TIFF viewers intended for end users may not be able to open the images or take advantage of color management and other features intended to ensure high-quality print output. |
| Clarity (high image resolution) | Excellent. Intended to support high-quality printing. See TIFF_6. |
| Color maintenance | The primary color space for this standard is CMYK since the intended output is via ink on paper. The 2004 edition of the standard added support for an expanded LW palette (up to 65,535 colors) and support for up to 32 separations. Other color spaces and the use of ICC Profiles are supported, but the P1 profile is limited to CMYK. |
| Support for vector graphics, including graphic effects and typography | See TIFF_6 |
| Functionality beyond normal rendering | Intended only for rendering to print. |
| Tag | Value | Note |
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| Filename extension | See related format. |
See TIFF_6 |
| Internet Media Type | See related format. |
See TIFF_6 |
| Magic numbers | See related format. |
See TIFF_6 |
| General |
The ISO 12639:2004 (Second edition) standard for TIFF/IT specifies three levels of conformance: TIFF/IT (also referred to as full TIFF/IT), TIFF/IT-P1 and TIFF/IT-P2. TIFF/IT-P1 conformance provides a minimized set of options to permit simpler implementation and compatibility, where possible (for CT, BP, and MP files), with commonly available TIFF 6.0 readers and writers. TIFF/IT-P2 incorporates all of the options defined for TIFF/IT-P1 and, in addition, provides support for spot colors, a larger LW color palette, the SD file format for screened data, and additional compression methods. The P2 profile was new in the second edition of the standard. Formally, not all valid TIFF/IT images are valid TIFF 6.0 images. This is because requirements for tag fields and values go beyond those explicitly part of TIFF 6.0. Hence, in a formal sense, TIFF/IT is not a true subtype of TIFF 6.0. However for most purposes, particularly relating to documentation, it is less confusing to consider TIFF/IT a subtype of TIFF 6.0 subject to exceptions. Tools such as JHOVE, for validating and characterizing TIFF images, will probably treat all TIFF variants as subtypes of a generalized TIFF data structure. In practice, not all TIFF readers intended for end users can handle all valid TIFF 6.0 files; when considering tools to use for rendering TIFFs, it will be necessary to understand the particular limitations of each piece of software. |
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| History |
The initial version of TIFF/IT as a prepress industry standard was documented in an ANSI standard known as IT8.8 (which had the same title as the later ISO standard). A key player in the development at this stage was DDAP (then the Digital Distribution of Advertising for Publication, now Digital Directions in Applications for Production). IT8.8 was used as input to the work in ISO/TC130 which resulted in ISO 12639. The ISO standard was developed and is maintained by ISO/TC 130/WG2/TF1 (TIFF/IT). NPES, The Association for Suppliers of Printing, Publishing and Converting Technologies serves as the Secretariat for the US Technical Advisory Group to ISO TC 130. From 1992 - 2005, DDAP (Digital Distribution of Advertising for Publications) Association was a leading graphic arts industry group charged with promoting "Universal Exchange of Advertising through Open Process Integration and Accredited Standards". DDAP joined IDEAlliance as a Network Group and updated its acronym to "Digital Directions in Applications for Production" in order to reflect its new mission. In early 2004, DDAP had on its web site a recommendation of ISO 12639:1998 TIFF/IT-P1 for the delivery of digital advertising material. As of July 2005, the DDAP web site has no mention of TIFF/IT, but does promote the use of PDF/X. |
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