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Digital Preservation

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TIFF tags. Content Categories >> Still Image | Sound | Textual | Moving Image | Web Archive | Datasets | Geospatial | Generic Introduction The flexible and extensible TIFF format has provided long service for digital imaging.

TIFF tags

TIFF files declare and describe their content by means of tags in the header and in Image File Directories (IFDs) within the file. Tags can indicate the basic geometry of the image, define how the image data is arranged, and indicate such facts as whether one or another image compression option has been used. TIFF tags defined by the 1992 TIFF 6.0 specification fall in the first two source categories listed below: baseline and extended. The specification also established procedures for further extension, and this has led to the establishment of tags in the two additional categories: private and private IFD.

The TIFF specification requires that tags be encoded in numerical order and that is the sequence used in the table below. Sources for tag specifications • TIFF Baseline.

Digitization

Digital Photographs. Quality and Functionality Factors for Still Images. Content Categories >> Still Image | Sound | Textual | Moving Image | Web Archive | Datasets | Geospatial | Generic Scope The factors discussed here apply to still images that convey their meaning in visual terms, e.g. pictorial images, photographs, posters, graphs, diagrams, documentary architectural drawings. Formats for such images may be bitmapped (sometimes called raster), vector, or some combination of the two. A bitmapped image is an array of dots (usually called pixels, from picture elements, when referring to screen display), the type of image produced by a digital camera or a scanner. Vector images are made up of scalable objects—lines, curves, and shapes—defined in mathematical terms, often with typographic insertions.

Graphic design software may be primarily of the paint variety and intended to produce bitmapped images or primarily of the draw variety and intended to produce vector images. For specialized professional applications, clarity is often of great importance. Additional Reading. E-Journals and Blogs Covering Digital PreservationD-Lib Magazine First Monday RLG DigiNews - Archived articles available DPC/PADI What's New in Digital Preservation The Ten Thousand Year Blog Digitization 101 The Signal International Journal of Digital Curation Additional ResourcesArts and Humanities Data Service.

Additional Reading

Bailey, Charles W. British Library Digital Preservation Strategy, 2013 - 2016. Resources - Federal Agencies Digitization Guidelines Initiative. January 28, 2010 The successful creation and maintenance of digital images depends on a complex network of formal standards and consensus-based best-practice guidelines.

This resource list focuses on technical standards. The term “standards” is often used rather loosely, but in this guideline, it refers to voluntary standards developed by industry, such as Adobe; by standards bodies, such as the Association for Information and Image Management (AIIM); or by Standards Developing Organizations, such as the International Organization for Standardization (ISO). The ISO/IEC Information Center is one source of information about the standards process; another excellent reference on how standards are defined and categorized can be found on Wikipedia.

University Library - Digital Imaging Guidelines. Digital Imaging Guidelines Scanning and Saving Master Images Here are some basic guidelines for converting original documents, images, manuscripts, etc. into digital master images, from which derivative images can be made for various presentations. Black and White Images (text, line drawings) For images and illustrations with no tonality (only blacks and whites) 600 dpi, 1-bit or bitonal TIFF images 600 dpi will achieve an archival replication of the original.

Sized and saved at 1:1 scale to the dimensions of the original page saved uncompressed or with lossless compression (LZW for TIFF images, or JPEG 2000) IrfanView - Official Homepage - one of the most popular viewers worldwide. DPC Technology Watch Reports: ISSN 2048-7916. The DPC Technology Watch Report series is intended as an advanced introduction to specific issues for those charged with establishing or running services for long term access. They identify and track developments in IT, standards and tools which are critical to digital preservation activities.

They are commissioned by experts on these developments and are thoroughly scrutinised by peers before being released. Authors are asked to provide reports that are informed, current, concise and balanced; lower the barriers to participation in digital preservation; derive from the needs of the Coalitions members; and are of utility to members and non-members alike. There are currently 15 reports published in the series: File Format Migration. Formats are for saving When an image file is saved, all the bits in the file need to be stacked up in some way so they can be decoded. A file format is a formula for stacking up those bits so various programs can understand them. There quite a few different images formats in use, and many of the variations are slight, such as the differences between CR2 files produced by different Canon cameras.

Some of the differences are large and significant, such as that between a TIFF file and a JPEG file. If an image can be opened, it can be saved to a new format. Know what you've got Unfortunately, there's no one who can monitor what file types you have in your collection except you. We strongly suggest that you keep a primary copy of your archive on available storage of some sort, rather than in a drawer that is out of sight. Avoiding obsolescence The most critical reason to do a format migration is because the current format is in danger of becoming unreadable.