Editing S3 Texture Compression (section)

{{Short description|Texture compression algorithm}}
{{Infobox software
| name                   = S3 Texture Compression (S3TC)
| logo                   = 
| logo_size              = 
| developer              = [[S3 Graphics]]
| released               = {{Start date and age|1998|}}
| latest_release_version = 
| latest_release_date    = 
| operating system       = [[Microsoft Windows]]
| genre                  = [[texture compression]]
}}
'''S3 Texture Compression''' ('''S3TC''') (sometimes also called '''DXTn''', '''DXTC''', or '''BCn''') is a group of related [[lossy compression|lossy]] [[texture compression]] [[algorithm]]s originally developed by Iourcha et al. of [[S3 Graphics|S3 Graphics, Ltd.]]<ref>{{patent|US|5956431|"Fixed-rate block-based image compression with inferred pixel values"}}</ref><ref>{{cite patent|title=System and method for fixed-rate block-based image compression with inferred pixel values|pubdate=Sep 21, 1999|inventor-last=Iourcha|inventor2-last=Nayak|inventor3-last=Hong|inventor-first=Konstantine I.|inventor2-first=Krishna S.|inventor3-first=Zhou|country=US|number=5956431}}</ref> for use in their [[Savage 3D]] [[computer graphics accelerator]]. The method of compression is strikingly similar to the previously published [[Color Cell Compression]],<ref>{{cite journal|title=1990 IEEE Color Cell Compression Paper|last=|first=|date=|publisher=[[IEEE]]|doi=10.1109/TENCON.1990.152671|s2cid=62015990}}</ref> which is in turn an adaptation of [[Block Truncation Coding]] published in the late 1970s. Unlike some image compression algorithms (e.g. [[JPEG]]), S3TC's fixed-rate data compression coupled with the single memory access (cf. Color Cell Compression and some [[Vector quantization|VQ]]-based schemes) made it well-suited for use in compressing [[texture mapping|textures]] in hardware-accelerated [[3D computer graphics]]. Its subsequent inclusion in [[Microsoft]]'s [[DirectX]] 6.0 and [[OpenGL]] 1.3 (via the GL_EXT_texture_compression_s3tc [[OpenGL#Development|extension]]) led to widespread adoption of the technology among hardware and software makers. While S3 Graphics is no longer a competitor in the graphics accelerator market, license fees have been levied and collected for the use of S3TC technology until October 2017, for example in [[game console]]s and graphics cards. The wide use of S3TC has led to a [[de facto]] requirement for OpenGL drivers to support it, but the patent-encumbered status of S3TC presented a major obstacle to [[Open-source software|open source]] implementations,<ref>{{cite web |url=http://dri.freedesktop.org/wiki/S3TC |title=S3TC situation on official DRI information page |publisher=Dri.freedesktop.org |date= |access-date=2012-01-25 |archive-date=2012-01-19 |archive-url=https://web.archive.org/web/20120119112130/http://dri.freedesktop.org/wiki/S3TC |url-status=live }}</ref> while implementation approaches which tried to avoid the patented parts existed.<ref>[https://www.phoronix.com/scan.php?page=article&item=s2tc_s3tc_fix S2TC: A Possible Workaround For The S3TC Patent Situation] {{Webarchive|url=https://web.archive.org/web/20160513050935/http://www.phoronix.com/scan.php?page=article&item=s2tc_s3tc_fix |date=2016-05-13 }} on [[phoronix]]</ref>