Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Imaged Record Format Options File Format Technical Considerations Recommended Use TIFF Seen as the “De facto” standard for image files Widely supported and used Commonly used for desktop publishing and medical imaging applications Supports multi-page images Offers compression options: uncompressed, lossless LZW, and run length compression Supports multiple compression types for 1-bit files JPEG compression not recommended in TIFF file Accommodates internal technical metadata in header/extensible and customizable header tags Supports Adobe’s XMP (Extensible Metadata Platform) Accommodates large number of color spaces and profiles High-bit compatible Can support layers, alpha channels Accommodates large file sizes Preferred raster image format for preservation Long track record – developed in 1986 Not suitable as access file—no native support in current web browsers Preferred format for production master file PNG Lossless compression Portable Well-compressed storage format for images Open-source and patent free Second edition PNG is an ISO standard – ISO/IEC 15948:@003 (E) Not widely adopted by imaging community High-bit compatible Supports alpha channels Native support available in later web browsers as access file Possible format for production master file not currently widely implemented Not yet widely adopted Offers new compression techniques Offers a lossless compression option Supports additional bit depths Supports multiple resolutions Compatible with many viewers and web browsers More complex model for encoding data (content is not saved as raster data) Extended version supports color profiles Extended version supports layers Support for extensive metadata encoded in XML “boxes;” particularly technical, descriptive, and rights metadata Has been published as an ISO standard, ISO/IEC 154441:2000 Possible format for production master file not currently widely implemented JPEG2000 GIF Long track record – developed in 1987 Supported by all web browsers Limited color palette - supports 8-bit color or grayscale, color images are dithered Commonly used for illustrations, black and white images, logos, and line drawings Access derivative file use only -recommend for text records Scanning and Microfilming Strategy File Format Technical Considerations Recommended Use Not suited for photographs Uses lossless LZW compression Short decompression time JFIF/JPEG JFIF format is platform independent Commonly used on the world wide web Best used for complex graphics and photographs JFIF uses the JPEG glossy compression Level of compression is adjustable at time of creation Smaller files Supports a limited number of color spaces: 8-bit gray and 24-bit color but not 1-bit bi-tonal Longer decompression time Supports only a limited set of internal technical metadata Not suitable format for editing image files—saving, processing, and resaving results in degradation of image quality after about three saves Access derivative file use only - not recommended for text or line drawings PDF Access derivative file use only – recommend for records accessed over the internet. Adapted from: Widely used Proprietary file format Released in 1993 Encapsulating format, not raster image format Provides consistency across programs and platforms Cannot be used to capture digitized records directly, a native format must be captured first, such as TIFF Resolution reduction, OCR, and image correction cannot be performed directly on a PDF – these functions must be carried out before encapsulation or the original formats must be retained separately Captures text and images in their original format, preserving fonts, graphics, and layouts Commonly used on the world wide web Adobe Reader is required to view PDFs or a tool that embeds the capability Supports multiple compression schemes Supports a limited number of color spaces – 8-bit palletized, 16-bit grayscale, and 48-bit color More complex format due to embedded/externally linked objects Implements Adobe’s XMP specification for embedding metadata in XML PDF/A has been introduced as a preservation standard for PDF – ISO 19005-1:2005 http://www.archives.gov/research/arc/digitizing-archival-materials.pdf http://www.archives.qld.gov.au/publications/digitisation/digiguideline.pdf 1