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Last modified: June 10, 2002
DIG35: Metadata Standard for Digital Images

[March 28, 2002] Some broken links below are in the process of being repaired. Version 1.1 of the DIG35 Specification. Metadata for Digital Images was published June 18, 2001. Version 1.0 and 1.1 of the specification are available with an XML-based reference implementation. "The focus of the DIG35 Initiative Group is on defining metadata standards. By establishing standards, the Initiative Group seeks to overcome a variety of challenges that have arisen as the sheer volume of digital images being used has increased. Among these are efficiently archiving, indexing, cataloging, reviewing, and retrieving individual images, whenever and wherever ne A key decision made by the DIG35 Initiative Group was the choice of XML (Extensible Markup Language) as the recommended reference implementation structure. XML offers a ready-made environment within which vendors of digital imaging applications and devices can rapidly incorporate the advantages of metadata structures... In keeping with I3A overall role as cross-organizational, industry-wide coordinating organization, the DIG35 Initiative and other DIG Initiatives have also maintained close interaction with related standards-setting bodies. Primarily, these include ISO's JPEG-2000 and MPEG-7 committees. In addition, the group has closely tracked the development of XML, as well as other Internet standards."

[September 02, 2000] The DIG35 Initiative Group, operating within the sphere of the consortial 80-member Digital Imaging Group, focuses upon digital image metadata standards to support efficient archiving, indexing, cataloging, reviewing, and retrieving individual images. Members of the DIG35 Initiative Group have now released the DIG35 Specification: Metadata for Digital Images. Version 1.0. XML is the recommended DIG35 implementation format. "The DIG35 Metadata Specification includes the following: (1) An overview of the specification, useful for anyone interested in understanding metadata and the potential uses as well as the basics of the DIG35 Metadata Specification. This overview comprises Chapters 1 through 5 of this document. (2) A series of technical annexes (Annex A through H) which provides the technical details of the Specification, the XML Reference Implementation, and other information of interest to those who are implementing the DIG35 Metadata Specification in their own work. (3) Several Appendices, which provide additional information, background information on metadata in general or the DIG35 Metadata Specification. These Appendices will be useful primarily to those implementing DIG35 into their own work. (4) A Glossary of terms and their definitions and references."

Examples of XML instance syntax and formal XML declarations for image metadata encoding are provided throughout the DIG25 specification; the declarations are collected in three appendices: ANNEX G: DIG35 XML DOCUMENT DEFINITION; ANNEX H: DIG35 XML SCHEMA COLLECTION (informative); ANNEX I: DIG35 XML DTD. W3C XML Schema (pages 105-124) is offered the principal notation: "The syntax is described using W3C's XML Schema language. The XML Schema language is used as it clearly defines the type of each metadata field, and the relationship between fields. XML is by no means the only encoding method for DIG35 metadata. The types of the fields and the relationship between the fields, described using XML Schema throughout this document, could also be used to describe DIG35 metadata stored, for example, in a relational database or a binary image file. NOTE: W3C's XML Schema is not a W3C Recommendation at the time of the publication of this specification, thus the actual syntax defined here is subject to change. However, the datatypes and relationships between fields that are represented as a schema should be consistent. The introductory document XML Schema Primer provides details on the XML Schema usage used in this specification. DIG35 supports the W3C's XML Schema effort and intends to revise the DIG35 recommended XML encoding method following publication of the XML Schema Recommendation by W3C." The XSD is also made available in a separate file. The XML DTD (pages 125-138) is also made available in a separate file. Namespaces: "Since DIG35 metadata may either incorporate other metadata for extensibility or be used in other applications, it is important to define an XML namespace specifically for DIG35 elements and attributes. Three namespace abbreviations are used throughout this specification. These namespaces are for XML, XML Schema and DIG35 definitions. The XML namespace: xmlns:xml=""; the XML Schema namespace: xmlns:xsd="". To specify the DIG35 XML namespace the following URI is defined; it should be used by experimental implementations: xmlns:dig35="". Caveat: "While DIG35 chose XML as a recommended implementation method especially for image metadata interchange, there are other means to exchange, store or stream image metadata within various systems. Several alternatives include: (1) Tag based binary encoding (e.g., TIFF) (2) Simple KEY-VALUE pair plain text (3) Relational/Object database systems (4) Other proprietary formats."

Rationale for the specification [1.0] is provided in the 'Preface'. This section reads, in part: "From the very beginning of photography (and, before that, in art of all kinds) those who take pictures have tried to capture as much information about the photograph as possible. This information is termed metadata. Every family has shoeboxes filled with photographs, some with a few cryptic notes on the back (which is metadata). Another method of tracking metadata has been in photo albums dedicated to special occasions. In both cases, the information has been limited and often the meaning of the notes is lost over time...Overall, creating metadata for images enhances our business opportunities, amplifies our memories and increases the joy of sharing. As we share images across distance and time, it becomes even more important to remember as much as possible about the image. In fact, in today's digital age, sharing images is easier than ever. The growth in digital technology has created a desire among users to manage and exchange their images in a variety of ways including storage, e-mail exchange, Internet/WWW postings and other displays (such as personal electronic photo albums or frames), and printing to a variety of devices with different resolutions. Indeed, personal processing of images can be organized into four primary areas of use: creation, editing, printing, and sharing. In terms that are more technical, this workflow is termed input, manipulation, output, and communication. The benefits for digital image use increases significantly by having more extensive metadata that is consistently available throughout this workflow. First, with digital metadata, the image becomes important not just for today but also in the future. Knowing exactly who, what, when, where, and how a photograph was taken provides a solid basis for documenting our lives and is an integral part of business. Second, using today's technology, images can be shared far more broadly and in the way most appropriate to each individual and functional requirement. This extensive sharing of images requires more knowledge about the image, especially in a business situation. Finally, knowing as much as possible about the image enhances sharing. We no longer need to rely on memory alone to provide the background for our most precious history or our corporate assets..."

[August 31, 2000] A recent announcement from the Digital Imaging Group describes the completion of the 'DIG35' Digital Imaging Metadata Standard, together with its specified XML encoding. Excerpt: "The Digital Imaging Group (DIG) today released the final DIG35 Metadata Specification providing a cohesive and consistent set of metadata definitions to the imaging industry. DIG35 provides the first persistent way for digital images to become rich, completely self-contained sources of information, regardless of where they travel on the global network. With millions of digital images now produced yearly, this capability is critical for enabling users to effectively organize, find, retrieve and share their images instantly. The specification also includes a reference encoding method using the current industry standard language XML. Using the XML DTD and schema provided, developers can easily implement the DIG35 Metadata Specification in their own imaging applications. Additionally, DIG35 can be used as a single standard interchange format between existing applications that each use different proprietary metadata formats, allowing users to greatly extend and leverage their existing intellectual capital investments. The DIG35 Metadata Specification has been reviewed by the public, by several universities, and by organizations such as the National Information Standards Organization (NISO) and the International Organization for Standardization (ISO) JPEG2000 Working Group. The relevant portions of the specification have been submitted to the JPEG2000 file format subgroup and have been incorporated into the JPEG2000 Part 2 specification committee draft. The DIG35 Metadata Specification, including the XML DTD and schema, is available today for public download on the DIG Web site. . . Businesses, professionals and consumers can all utilize metadata in order to manage images. For example, e-commerce businesses can manage and utilize their assets more effectively and efficiently by simply being able to quickly retrieve the right image for any given purpose. Instead of spending valuable time painstakingly looking at each image file to determine the content, businesses can search by any associated metadata to locate an image and read the descriptive elements. By using XML as the recommended encoding method, DIG35 is Internet ready and easy to implement on e-commerce sites. Professional photographers can associate information about camera settings, copyright information and image manipulation techniques within the image in order to recreate images and recap their work. Additionally, consumers can easily share their captured experiences by using metadata to tell the story or narration behind their images. For example, they can use image-editing software on their PC to add explanatory captions to each photo from their vacation in China, and then upload those photos to a photo sharing Web site. The DIG35 enabled photo Web site would understand and save all the captions, freeing the user from having to input the information a second time. Friends and family around the globe can then not only see the pictures, but also experience the entire story and history behind them in the storyteller's absence." Composed of 'approximately 80 member companies, the DIG is a consortium engaged in the development and introduction of innovative digital imaging standards and technologies.'

DIG35 XML encoding: "This specification recommends using the World Wide Web Consortium (W3C) XML (Extensible Markup Language) as the standard metadata interchange format. While other implementation methods are certainly possible, the primary reasons for choosing XML include: (1) XML is already widely adopted as a cross-platform and Internet-enabled implementation language; (2) Many applications within the imaging workflow can interface to XML structures; (3) XML provides a highly extensible method for creating device-independent, language-independent, and application-independent interchange formats; (4) XML is equally well-suited for handling relational or hierarchical data structures; (5) XML provides a solid foundation for implementing both human- and machine- readable and understandable metadata. Because the industry has already developed a robust set of tools for both writing and reading XML, it offers a ready-made environment which developers of digital imaging applications and devices can rapidly incorporate the advantages of metadata structures. In addition, the widespread usage of XML within the Internet community provides for an inherently smooth meshing of the metadata structures with underlying network transport mechanisms and Web-based communication methods." [from the version 1.0 WD] Note in the version 1.0 WD: "Annex H: DIG35 XML Syntax Definition" (BNF): "This annex specifies the XML encoding for the DIG35 metadata defined in Annex B-F. It defines the mapping between the fields in the definitions and the elements and attributes in XML. A Document Type Definition (DTD) is also specified to define this mapping (See Annex I). The DTD is not complex enough to define all constraints on the XML encoding of the metadata, and thus the DTD along with this document should be used to ensure valid metadata is created. When XML Schema becomes a standard, a XML Schema for metadata will also be defined." [From the WD]


  • DIG35 Initiative Group

  • I3A - the International Imaging Industry Association

  • [March 28, 2002] DIG35 Specification. Metadata for Digital Images. Version 1.1. June 18, 2001. 219 pages. From Digital Imaging Group, Inc. Annex H contains the DIG35 XML Schema; Annex I contains the DIG35 XML DTD. The official published specification for version 1.1 (with XML Schema and DTD) is available from the DIG35 Initiative Group.

  • [April 16, 2001] DIG35 Specification - Metadata for Digital Images. Version 1.1. Working Draft characterized as a "work in progress." April 16, 2001. 210 pages. From Digital Imaging Group, Inc. Prepared by the DIG35 Phase 2 Initiative Group. Note that the official specifications for version 1.1 are available from the DIG35 Initiative Group. Working draft copies (from BioCISE Project TDWG subgroup):

  • [August 30, 2000] DIG35 Specification: Metadata for Digital Images. Version 1.0. 'DIG35 Specification 2000-08-30'. August 30, 2000. Digital Imaging Group, Inc. 176 pages (32 references, glossary, index). Prepared as a recommendation by members of the DIG35 Initiative Group: Adobe Systems Inc., AGFA-GEVAERT N.V., Canon Inc., Eastman Kodak Company, Fuji Photo Film Co., Ltd., Hewlett Packard Company, Microsoft Corporation, NETIMAGE, PhotoChannel Networks Inc., PhotoWorks, Inc., PictureIQ Corporation, Polaroid Corporation, Comments on the recommendation should be sent to "The DIG35 Metadata Specification includes the following: (1) An overview of the specification, useful for anyone interested in understanding metadata and the potential uses as well as the basics of the DIG35 Metadata Specification. This overview comprises Chapters 1 through 5 of this document. (2) A series of technical annexes (Annex A through H) which provides the technical details of the Specification, the XML Reference Implementation, and other information of interest to those who are implementing the DIG35 Metadata Specification in their own work. (3) Several Appendices, which provide additional information, background information on metadata in general or the DIG35 Metadata Specification. These Appendices will be useful primarily to those implementing DIG35 into their own work. (4) A Glossary of terms and their definitions and references." See the separate XSD and DTD. The above URL for the Digital Imaging Group's DIG35 Metadata Specification for Digital Images communicated from DIG 02-Sep-2000. [cache XSD]; [cache DTD] The online copy from the DIG35 website is missing. [cache PDF from FU-Berlin]

  • [August 30, 2000] "Digital Imaging Group (DIG) Announces the Completion of DIG35, the Digital Imaging Metadata Standard. New Specification Available for Public Download on DIG Web Site For Developers of Imaging Products and Services."

  • The DIG35 Metadata XML Document Type Definition - As extracted from the DIG35 Working Draft 1.0, Annex I. March 6, 2000. From Matthew Kendall. [cache]

  • DIG35: Metadata for Digital Images. Working Draft, 1.0. March 6, 2000. Digital Imaging Group. 138 pages. Comments to "Scope: This specification defines a set of public metadata for digital still images, either as a single image or a collection of images, that could be supported and exchanged by current and future devices, software, and services in an open environment. In addition to the metadata definition, a recommendation for implementation is defined to enable exchange of such metadata. This specification does not concern itself with vendor specific/proprietary private metadata or a particular application domain. Private or application domain specific metadata should be defined within their respective organizations and is out of scope of this specification. This specification also does not mandate procedural metadata such as processing parameters that changes the visual appearance after decoding the image data (e.g., cropping, rotating etc.), printing information (e.g., number of copies, output size etc.) and ordering information (e.g., delivery and payment information). There are, however, exceptions at this time. Print Aspect Ratio (PAR) metadata is an example that does not follow this rule. Technical metadata that are well-defined and intended to produce better quality images that benefit the users without additional user effort are considered exceptions." [cache]

  • The Power of Metadata Is Propelling Digital Imaging Beyond the Limitations of Conventional Photography. Combining Optimized Convenience and Flexibility with Expanded Content and Embedded Intelligence. An Overview of the Opportunities for Implementing Metadata Standards." Digital Imaging Group, August 1999. An overview of the DIG35 initiative. "The focus of this paper and of the Digital Imaging Group's DIG35 Initiative Group is on the critical issue of defining metadata standards to optimize the ease-of-use, flexibility and range of application results that can be achieved with metadata-enhanced digital imaging. Ultimately, the vision of the DIG35 Initiative Group is to 'provide a standardized mechanism which allows end-users to see digital image use as being equally as easy, as convenient and as flexible as the traditional photographic methods while enabling additional benefits that are possible only with a digital format.' With this overall vision in mind, the key focus areas of the DIG35 Initiative Group include: (1) Defining a standard set of metadata for digital images that can be widely implemented across multiple image file formats; (2) Providing a uniform underlying construct to support semantic interoperability of metadata between various digital imaging devices; (3) Ensuring that the metadata structure provides both a common inter-application exchange format and a high-degree of extensibility for enhanced use by specific applications; and (4) Educating the industry at large regarding the importance of metadata usage, preservation and exchangeability... A key decision reached quickly by the DIG35 Initiative Group has been the choice of W3C's XML (Extensible Markup Language) as the recommended reference-implementation structure for representing standardized metadata. Because the industry has already developed a robust set of tools for both writing and reading XML, it offers a ready-made environment within which vendors of digital imaging applications and devices can rapidly incorporate the advantages of metadata structures. In addition, the widespread usage of XML within the Internet community provides for an inherently smooth meshing of metadata structures with underlying network transport mechanisms and Web-based communication methods. Overall the use of XML supports the DIG35 commitment that the metadata implementation needs to be extensible and flexible, to be small enough for limited memory requirements and yet, maintain human readability/understandability of the information. For digital imaging product developers, XML provides a highly-adaptable, standardized method for interchanging data between any digital imaging device, application and/or database without having to continually write new device-drivers from scratch as the specific products and applications evolve and change." [cache]

  • XML in JPEG 2000. JPEG 2000 Part I. Final Committee Draft Version 1.0 [ISO/IEC JTC 1/SC 29/WG 1 N1646R, Date: 16 March 2000]. Coding of Still Pictures. In the specification for the JP2 file format: "One important aspect of the JP2 format is the ability to add metadata to a JP2 file. Because all data is encapsulated in boxes, and all boxes have types, the format provides a simple mechanism for a reader to extract relevant information, while ignoring any box that contains information that is not understood by that particular reader... An XML box contains vendor specific data (in XML format) other than that data defined within this Recommendation | International Standard. There may be multiple XML boxes within the file, and those boxes may be found anywhere in the file except before the JP2 signature box. The type of an XML box is 'xml\040' (X'786D6C20'). The XML box provides a tool by which vendors can add XML formatted information to a JP2 file. The existence of any XML boxes is optional for conforming files. Also, any XML box shall not contain any information necessary for decoding the image to the extent that is defined within this part of this Recommendation | International Standard, and the correct interpretation of the data in any XML box shall not change the visual appearance of the image. All readers may ignore any XML box in the file." [cache]

  • DIG2000 file format proposal. ISO/IEC JTC1/SG29/WG1 N1017. October 30, 1998. 113 pages. By the Digital Imaging Group. (J. Scott Houchin, Chair, DIG2000 Working Group 901 Elmgrove Road, Rochester, NY 14653-5555 Tel: +1 716 726 7984; Fax: +1 716 726 7295; E-mail: ['The contents of this document represents a consensus of opinion from the following DIG member companies: Agfa, Canon, Corbis, Eastman Kodak, Fuji, Hewlett-Packard, Intel, Interactive Pictures, Iterated Systems, Konica, Live Picture, and TrueSpectra.'] "In the DIG2000 format, all metadata is stored using XML." Chapter 4.3 provides the XML DTD for the 'Metadata Root structure specification'. Chapter 5 defines "Standard metadata fields": "The standard fields are divided into logical blocks that can each exists on their own in a separate stream, each describing a different aspect of the image. The blocks are: (1) Digital Image Source (Section 5.1) (2) Intellectual Property (Section 5.2) (3) Content Description (Section 5.3) (4) GPS Information (Section 5.4) The information in these blocks provides the framework to document facts about image capture, intellectual property concerns, and descriptive information about the image itself. With some images, users need to know who is in the picture, where and when it was taken, and so on, to understand the significance of the image." See the extracted portion of the specification with the DIG2000 file format DTDs. [cache]

  • [February 2, 2000] "Digital Imaging Group To Release First Public Version of Image Metadata Standard." - "The Digital Imaging Group (DIG) today announced the first public release of its innovative image metadata specification, DIG35. The draft specification will be available for public review and comment on March 1, 2000; it is currently under private review by DIG members. Developed during a 16-month collaboration of the biggest household name companies -- AGFA-GEVAERT N.V., Canon Inc., Eastman Kodak Company, Fuji Photo Film Co., Ltd., Hewlett-Packard Company, Polaroid Corp. and Seattle FilmWorks -- along with hot new start-ups Digital Intelligence, Digitella Technology Inc., NETIMAGE and PhotoChannel Networks Inc., DIG35 will revolutionize the way images are managed across a wide range of consumer, business and professional applications. Other companies endorsing the DIG35 standard include ACD Systems, Alinari, Canto, Digimarc, G&A Imaging, Intel, Iterated Systems, IXLA, LizardTech, MGI Software, OpenGraphics, Pegasus and RCO. While the concept of image metadata is not new, DIG35 breaks many of the barriers within existing approaches. Current image formats such as EXIF (an extension of JPEG used by many digital camera manufacturers) and TIFF already support metadata, but have limitations in the amount and types of data that can be handled. Designed to be file format independent, DIG35 builds on the experience gained with these earlier efforts and adds specific CONTENT information previously lacking. Application developers, already familiar with XML and supporting existing metadata formats will find it easy to move to DIG35. One of the first major implementations of DIG35 is expected to be as an extension to the upcoming JPEG 2000 standard, currently in the final stages of ISO approval. The DIG35 Working Draft will be available for public review and comment from March 1-29, 2000. To be included on the notification list for public comment, send an email to The final specification is planned for release in the third quarter of 2000. Launched in October 1997, the DIG is an open-industry consortium created to expand the use of digital images across consumer, business and professional imaging markets and applications. Membership gives companies the opportunity to help define the evolving technical platforms in digital imaging, and to create solutions built on those foundations."

  • [February 04, 2000] "Digimarc Adopts XML for Digital Watermarking Technology." - "Digimarc Corporation, a leading provider of digital watermarking solutions, today announced that it has adopted Extensible Mark-up Language (XML) for use in the MediaBridge system, the company's breakthrough innovation bridging traditional and online media. The MediaBridge system allows readers to immediately and seamlessly link from interesting content in traditional media publications to relevant Internet destinations merely by showing the page to a Digimarc-enabled PC camera. Digimarc elected to use XML because it provides an independent, open standard supported by major software vendors for the exchange of data from magazine content to Web sites worldwide. The DIG35 Working Draft will be available for public review and comment from March 1-29, 2000. To be included on the notification list for public comment, send an email to The final specification is planned for release in the third quarter of 2000... Digimarc's technology is becoming the global de facto standard for digital watermarking in a variety of media industries. Over the last several years, the company has established a pervasive following in the still image market, supporting copyright protection, digital asset management, digital rights management, and business to business image commerce solutions. Earlier this week, Digimarc endorsed the Digital Imaging Group's (DIG) first public release of the DIG35 image metadata specification, a revolutionary way to manage images across a wide range of consumer, business and professional applications."

  • [August 31, 1999] "Digital Imaging Group to Enable Image Workflows Through Metadata Initiative. DIG35 Initiative Group recommends XML as interchange format. Liaison with MPEG-7 to drive common metadata architecture." - "The Digital Imaging Group (DIG), the digital imaging industry's premier consortium, disclosed its plans to enable a variety of image workflows through its metadata initiative, DIG35. The goal of the Initiative is to simplify the process of collecting and managing information about an image and in the process enable a broad range of applications from image management to digital photo finishing. XML Key to the Power of DIG35: XML, a W3C standard, will be a key technology in the implementation of the standard. XML's powerful data representation capabilities and its wide spread adoption in the Internet will allow virtually limitless flexibility. For example, take the problem of describing the location a picture was taken. Depending on the application domain, location in a consumer photograph could be a place name or a GPS coordinate. For medical images, location would represent a part of the body; for astronomical images, location would carry yet a different meaning. Liaison with MPEG-7: The DIG chose XML not only for its widely adopted use, but also for the opportunity to unify its work with a concurrent effort happening in the ISO MPEG Committee (ISO/IEC JTC 1/SC 29/WG 11), the MPEG-7 Group. The DIG35 Initiative recently formalized an official liaison with the MPEG Committee to collaborate with MPEG-7's effort in the area of still image metadata standardization. Through this partnership, the DIG will help define the metadata for still images within multimedia contents in order to help multimedia producers, owners and users manage their contents."

  • Contact for Digital Imaging Group (DIG): Shannon S. Costello (Membership and Operations Administrator). Phone: +1 (650) 697-8722; Fax: +1 (650) 697-8726.

  • "Image metadata" - Reference list maintained by Matthew Kendall (Vancouver, BC, Canada)

  • [June 10, 2002]   NISO and AIIM International Release Digital Still Images Metadata Standard for Review.    An XML Schema and accompanying Data Dictionary -- Technical Metadata for Digital Still Images has been published by the [US] National Information Standards Organization (NISO) and AIIM International for 18-month review as a Draft Standard for Trial Use. A NISO 'Draft Standard for Trial Use (DSFTU)' is typically released when there is a need for field experience before proceeding with balloting; the extended time period "allows implementers to test the standard; at the end of the trial period the standard may be balloted, revised or withdrawn." The data dictionary "defines a standard set of metadata elements for digital images. Standardizing the information allows users to develop, exchange, and interpret digital image files. The dictionary has been designed to facilitate interoperability between systems, services, and software as well as to support the long-term management of and continuing access to digital image collections." An (informative) Annex A presents the MIX Z39.87 XML schema under the name 'NISO Metadata for Images in XML (NISO MIX).' This XML schema "supplies a set of technical data elements required to manage digital image collections; the schema provides a format for interchange and/or storage of the data specified in the dictionary." [Full context]

  • [November 06, 2000] Data Dictionary -- Technical Metadata for Digital Still Images. Working Draft Standard, 1.0. July 5, 2000. 45 pages. The data types are presented in an XML schema definition (DIG35); Camera Capture Settings are in XML, per schema definition in DIG35 B.3.2.5. Note: "DIG35 provides seamless integration with the Internet by utilizing XML (the recommended implementation method). Since this dictionary makes no recommendation regarding metadata encoding (see Implementation Guidelines below) the decision to accept or reject DIG35's adoption of XML is forwarded to the NISO Standards Committee." Description: "Libraries, academic institutions, archives, museums, historical societies, government agencies, and private companies are engaging in imaging initiatives to create digital collections of their textual, visual, and artifact collections. However, as revealed by the 1999 Image Metadata Workshop, which was sponsored by NISO, Research Libraries Group (RLG), and the Council on Library and Information Resources (CLIR), there is little consistency in the technical metadata accompanying these images. Work to date on image metadata has focused on defining descriptive elements for discovery and identification. Little attention has been paid to defining the types of information that describe the capture process and technical characteristics of the digital images. This standard is much needed in the digital imaging community as technical metadata is perceived as an essential component of any digitization initiative for short-term and long-term management purposes. Technical metadata must be recorded accurately and consistently to ensure that the image files remain useable well into the future. Whether the images are pictorial or textual, the challenge remains the same -- ensuring the longevity of digital image collections. Preferably, part of this challenge can be addressed by building systems to store and process information about these files - the technical metadata. However, metadata must be standardized to allow this kind of a systematic approach in recording and managing technical image information."

  • NISO Comment Draft: NISO Data Dictionary for Technical Metadata for Digital Still Images. Draft Standard Out-for-Comment [February 16, 2001 - April 16, 2001]. Summary: "Technical metadata describing various aspects of image characteristics and the capture process, is an essential component of any digitization initiative. This type of metadata is required to support image quality assessment and image enhancement and processing, and is crucial for long-term collection management to ensure the longevity of digital collections. Up to now, image metadata work within the library and cultural heritage community has focused on defining descriptive elements for discovery and identification. The goal of the NISO Technical Metadata for Digital Still Images Standards initiative is to fill this gap by developing a generalized technical metadata standard applicable to all images no matter how they are created. NISO Standards Committee AU has released the first draft Data Dictionary for Technical Metadata for Digital Still Images. You are invited to review and comment on this draft." Available as, [cache.

  • [March 28, 2001]   TIFF Helper Creates XML-enhanced TIFF Images.    Eric Lease Morgan has created a collection of XML-enhanced TIFF images based on his water collection, 'automagically' creating a set of browsable HTML files allowing you to view the images and their descriptions in your Web browser. He says: "XML data was extracted from the description tags of TIFF files and converted into HTML through XSLT, the TIFF files were converted into thumbnail images, and the whole thing was brought together by creating a simple browsable list. The process begins with TIFF Helper, a rudimentary web-based application allowing people to write XML data to the description tag of TIFF files. The primary goal of TIFF Helper is to provide a means for 'marrying' the description of an image file with the image itself and not having to rely on an second application (say a database) to save and manage this information. Embedding descriptive information about images in the image files themselves provides a means for image archiving and distribution that is standards-based as well as operating system- and application-independent. If TIFF files were enhanced with XML data, then the descriptions of those files could be directly associated with their images. demonstrates one way of extracting that XML data and making sets of TIFF images available on the Web." The production code and XSLT stylesheets are available for download. Emerging graphics standards do use XML in similar ways, of course (e.g., MPEG-7 XML-based Description Definition Language, SVG, DIG35). [Full context]

  • Compare: Describing and retrieving photos using RDF and HTTP. W3C Note, 03 May 2000. "This note describes a project for describing and retrieving (digitized) photos with (RDF) metadata. It describes the RDF schemas, a data-entry program for quickly entering metadata for large numbers of photos, a way to serve the photos and the metadata over HTTP, and some suggestions for search methods to retrieve photos based on their descriptions. The data-entry program has been implemented in Java, a specific Jigsaw frame has been done to retrieve the RDF from the image through HTTP. The RDF schema uses the Dublin Core schema as well as additional schemas for technical data. Also: RDFPic is a tool to embed an RDF description of a picture into the picture itself, per the W3C Note. "Rdfpic is built around the concept of an rdf 'schema'." [cache]

  • Compare: "An Indexing and Querying System for Online Images Based on the PNG Format and Embedded Metadata." By Jane Hunter and Zhimin Zhan (DSTC Pty Ltd, Uni. of Queensland, Qld, 4072, Australia). September, 1999. "In this paper we describe an indexing, querying and browsing system for online images based on the PNG (Portable Network Graphics) image format and its ability to embed structured metadata within the image. First we describe a Java application which enables the computer-assisted generation and editing of Dublin Core-based metadata descriptions for digital images and the annotation of regions within images. This application integrates an image display window with a graphical user interface and metadata input forms generated from a hierarchical Resource Description Framework (RDF) schema. The schema definition is also used to validate the input descriptions and control the format of the output. At "Save" time, the image is converted from GIF or JPEG to PNG format and the validated metadata which has been input is embedded within the image. Secondly we describe an image-capable search engine developed through a simple code extension to DSTC's existing HotMeta web-page search engine. HotMeta crawls across the WWW extracting metatags from web pages and storing them in an indexed repository to enable searching. A simple code extension to HotMeta has enabled image search capabilities. Whenever HotMeta encounters a PNG image, it opens the image, extracts the metadata and saves this in the indexed repository. Finally we describe an improved image browsing method which exploits the metadata embedded in thumbnail PNG images. Clicking on a PNG thumbnail runs a cgi script which opens the thumbnail image, extracts the metadata and displays the full scale JPEG image, with annotated image maps, and other relevant embedded metadata - eliminating the need for backend databases or static web pages. This prototype system has been developed using digital images of historical photographs from the State Library of Queensland's (SLQ) John Oxley library. In particular, we have used historical photographs of Queensland from the William Boag Photographic Collection from the 1870's."

  • See also: "Supporting MetaData in Image Files through GDI+". "Microsoft is encouraging industry groups and vendors who define image file formats to specify and support a baseline set of metadata to help promote widespread use of specific metadata by the industry and consumers. This article discusses how Microsoft is supporting metadata with GDI+ and recommends enhancements for metadata support in the industry. Integration of relevant metadata in images provides an opportunity for participating industries to take imaging to the next level. Image metadata is essentially non-picture information that is bundled with picture information in a file. Metadata can include information such as the date and time the picture was taken, whether a flash was used, which camera model was used, and even audio annotations. Metadata is a key supporting technology for content management... Microsoft is supporting metadata in image files through GDI+, the next-generation graphics engine for 2D vector graphics, imaging, and typography for Windows-based and Web-based applications. GDI+ supports a number of native still image file formats, including BMP, JPEG, TIFF, PNG, GIF, WMF, and EMF. In turn, GDI+ provides core services for managing files in these formats to Microsoft Windows platforms. Vendors can use GDI+ to read and modify metadata in image files. Vendors can also use GDI+ to implement image codecs for proprietary file formats that would enable any GDI+ application to seamlessly open files in those formats. ..." [cache overview, .DOC article]

  • The IPTC published a list of keywords for describing photo-journalistic images ('IPTC field codes')

  • [April 23, 2001] Related: "AIIM International Announces XML Standards Initiative for the Exchange of Document Images and Related Metadata. New Standard will Enable XML Users to Leverage Existing Software Systems and Expertise to Exchange Images of Documents, Related Indices, and Metadata." - "AIIM International, the Enterprise Content Management (ECM) industry association, today [2001-04-20] announced the development of a new project investigating the methods of using Extended Markup Language (XML) tags to facilitate the exchange of information managed by document management technologies, including the associated metadata defining and/or describing the information to be shared..."

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