Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Scalable Vector Graphics (SVG) 1.1 |
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| Description | SVG is a language for describing two-dimensional graphics in XML (version 1.0). SVG allows for three types of graphic objects: vector graphic shapes (e.g., paths consisting of straight lines and curves), raster graphics (raster images), and text. Graphical objects can be grouped, styled, transformed and composited into previously rendered objects. The feature set includes nested transformations, clipping paths, alpha masks, filter effects and template objects. SVG may also be used for animations; see Notes below. |
| Production phase | Generally a final-state (end-user delivery) format. |
| Relationship to other formats | |
| Subtype of | XML, |
| Has earlier version | Scalable Vector Graphics (SVG), Version 1.0 (2001), not described at this Web site. |
| Has later version | Scalable Vector Graphics (SVG), Versions 1.2 and 2.0. As of February 2012, these are both described as being in draft; some commentators foresee that only version 2.0 will be fully realized, with publication anticipated in 2013. Not described at this Web site at this time. |
| Has subtype | Two simplified profiles of SVG 1.1 for mobile devices: SVG Basic and SVG Tiny (current version 1.2), not described at this Web site at this time. |
| Used by | EPUB_2, EPUB, Electronic Publication, Version 2. EPUB_2 readers are required to recognize and display embedded SVG images. |
| Used by | EPUB_3, Electronic Publication, Version 3. EPUB_3 uses a restricted subset of SVG 1.1 to represent inline vector graphics in documents based on XHTML and in standalone SVG-based EPUBs. |
| LC experience or existing holdings | None |
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| LC preference | None |
| Disclosure | Open standard from W3C |
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| Documentation | Scalable Vector Graphics (SVG) 1.1 (Second Edition). SVG_1_1 was originally published in 2003. The Second Edition includes all the errata and clarifications but no new features, released on August 16, 2011. |
| Adoption |
Many enthusiatic users and groups; see Useful references below. Browser support has varied with many complaints about lack of support by Internet Explorer; this has been remedied in IE 9 (2011). SVG is supported in Adobe tools, Visio (Microsoft), Corel Draw 11, and as an export format by ESRI ArcGIS. There are several open source applications and software libraries that can read and write SVG images. SVG is a preferred format for the FCLA Digital Archive. The October 2011 EPUB_3 specification for Electronic Publications uses a restricted subset of SVG_1_1 as a content document format for graphics, including use as a top-level format for comics and graphic novels. Not supported in EPUB_3 are animations and embedding of "foreign objects" in forms other than XHTML. |
| Licensing and patents | No special issues. As of January 2004, the SVG Working Group was not aware of any royalty-bearing patents they believe to be essential to SVG. |
| Transparency | Based on XML, hence inherently transparent. |
| Self-documentation | Includes <metadata> element designed to hold elements from other XML namespaces. Hence an SVG file can contain rich descriptive or administrative metadata using any other DTD. SVG 1.1 uses a DTD, not an XML Schema. |
| External dependencies | None |
| Technical protection considerations | None |
| Still Image | |
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| Normal rendering | Good support. |
| Clarity (high image resolution) | Scalable. Optional settings for rendering hints: crispEdges and geometricPrecision. |
| Color maintenance | SVG colors are specified in the sRGB color space. SVG content can specify an alternate color specification using an ICC profile (see the ICC Profile Format Specification). If ICC-based colors are provided and the SVG user agent supports ICC color, then the ICC-based color takes precedence over the sRGB color specification. |
| Support for vector graphics, including graphic effects and typography | Rich support. |
| Support for multispectral bands | Not applicable. |
| Functionality beyond normal rendering | Support for animations. Text in alternate languages for labels, etc. |
| Tag | Value | Note |
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| Filename extension | svg |
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| Internet Media Type | image/svg+xml |
Proposed in standards documentation. |
| Internet Media Type | image/svg-xml |
Found in practice. |
| General |
SVG files can be used for animations but there appears to be little or no practice of doing this. Most web sites present simple animations as GIF_89a files and more complex animations and interactives as Flash SWF_7 or SWF_8 files (or later versions). Commentators with an interest in animation, including advocates for SVG as a publicly disclosed format, have compared SVG and SWF but they note that the powerful authoring software available for Flash gives SWF the edge. |
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| History |
Version 2 of SVG has been under development for several years. As of March 2012, the intent is to be ready to publish a new recommendation in 2013. See SVG2 Planning Page at W3C. The new version will be built in modular fashion, with several modules designed for incorporation into either SVG_1_1 or SVG2. |
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