Editing OpenType (section)

==History==

OpenType's origins date to Microsoft's attempt to license [[Apple Computer|Apple]]'s advanced typography technology [[Apple Advanced Typography|GX Typography]] in the early 1990s. Those negotiations failed, motivating Microsoft to forge ahead with its own technology, dubbed "TrueType Open" in 1994.<ref>{{cite web |url=http://www.suitcasetype.com/images/font/dederon%20Serif%20Std%20OT/01_Dederon_Serif_Std_OT.pdf |title=Suitcase Type Foundry Information Guide] |archive-url=https://web.archive.org/web/20061118080709/http://www.suitcasetype.com/images/font/dederon%20Serif%20Std%20OT/01_Dederon_Serif_Std_OT.pdf |archive-date=November 18, 2006 }}</ref> Adobe joined Microsoft in those efforts in 1996, adding support for the [[glyph]] outline technology used in its Type 1 fonts.

The joint effort intended to supersede both Apple's TrueType and Adobe's [[Type 1 font|PostScript Type 1 font format]], and  to create a more expressive system that handles fine typography and the complex behavior of many of the world's writing systems. The two companies combined the underlying technologies of both formats and added new extensions intended to address their limitations. The name OpenType was chosen for the joint technology, which they announced later that year.

===Open Font Format===
Adobe and Microsoft continued to develop and refine OpenType over the next decade. Then, in late 2005, OpenType began migrating to an open standard under the [[International Organization for Standardization]] (ISO) within the [[MPEG]] group, which had previously (in 2003) adopted OpenType 1.4 by reference for [[MPEG-4]].<ref name="OFF-chiariglione">{{cite web |url=http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-off/index.htm |title=ISO/IEC 14496-22 "Open Font Format" |author=ISO/IEC JTC 1/SC 29/WG 11 |publisher=chiariglione.org |archive-url=https://web.archive.org/web/20100430175925/http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-off/index.htm |date=July 2008 |archive-date=2010-04-30 |access-date=2020-02-21}}</ref><ref>{{cite web|url=https://www.adobe.com/aboutadobe/pressroom/pressreleases/200508/081505OpenTypeISO.html |title=ISO To Adopt OpenType File Format as Font Standard For MPEG-4 |publisher=Adobe Systems Incorporated |date=2005-08-15 |access-date=2010-01-28 |url-status=dead |archive-url=https://web.archive.org/web/20110605091909/http://www.adobe.com/aboutadobe/pressroom/pressreleases/200508/081505OpenTypeISO.html |archive-date=2011-06-05 }}</ref><ref>{{cite web|url=http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n55201.doc |title=Referencing Explanatory Report to accompany FPDAM/FDAM Submission of ISO/IEC 14496–11/Amd.2, Referenced Specification: The OpenType font format specification, version 1.4. |date=July 2003 |format=DOC |access-date=2010-01-28  |url-status=dead |archive-url=https://web.archive.org/web/20140512223957/http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n55201.doc |archive-date=2014-05-12 }}</ref><ref>{{cite web|url=http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n6929t.doc |title=Combined CD Registration and CD Consideration Ballot on ISO/IEC CD 14496-22: Information technology – Coding of audio-visual objects – Part 22: Open Font Format – SC 29/WG 11 N 7485 |date=2005-09-01 |format=DOC |access-date=2010-01-28  |url-status=dead |archive-url=https://web.archive.org/web/20140512223958/http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n6929t.doc |archive-date=2014-05-12 }}</ref> Adoption of the new standard reached formal approval in March 2007 as ISO Standard [[ISO/IEC]] 14496-22 (MPEG-4 Part 22) called '''Open Font Format''' (OFF, not to be confused with [[Web Open Font Format]]),<ref>{{cite web|url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=43466 |title=ISO/IEC 14496-22:2007 – Information technology – Coding of audio-visual objects – Part 22: Open Font Format |publisher=ISO |date=2009-07-31 |access-date=2009-11-11}}</ref> sometimes referred to as "Open Font Format Specification" (OFFS).<ref name="OFF-chiariglione" /> The initial standard was technically equivalent to OpenType 1.4 specification, with appropriate language changes for ISO.<ref>{{cite web |url=http://standards.iso.org/ittf/PubliclyAvailableStandards/c043466_ISO_IEC_14496-22_2007(E).zip |title=ISO/IEC 14496-22, First edition 2007-03-15, Information technology — Coding of audio-visual objects — Part 22: Open Font Format |format=ZIP |date=2007-03-15 |author=ISO |access-date=2010-01-28}}</ref> The second edition of the OFF was published in 2009 (ISO/IEC 14496-22:2009) and was declared "technically equivalent" to the "OpenType font format specification".<ref name="ISO-2nd-edition">{{cite web |url=http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136 |title=ISO/IEC 14496-22:2009 – Information technology – Coding of audio-visual objects – Part 22: Open Font Format |publisher=ISO |date=2009-07-31 |access-date=2010-01-28}}</ref><ref>{{cite web |url=http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip |title=ISO/IEC 14496-22, Second edition 2009-08-15, Information technology — Coding of audio-visual objects — Part 22: Open Font Format |format=ZIP |date=2009-08-15 |author=ISO |access-date=2010-01-28}}</ref> Since then, OFF and OpenType specifications have been maintained in sync. OFF is a free, publicly available standard.<ref>{{cite web|url=http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html |title=Publicly Available Standards |publisher=Standards.iso.org |access-date=2009-11-11}}</ref>

By 2001 hundreds of OpenType fonts were on the market. Adobe finished converting their entire font library to OpenType toward the end of 2002. {{As of|2005|alt=As of early 2005}}, around 10,000 OpenType fonts had become available, with the Adobe library comprising about a third of the total. By 2006, every major [[Type foundry|font foundry]] and many minor ones were developing fonts in OpenType format.{{Citation needed|date=July 2011|reason=uncited statistics}}

===Unicode Variation Sequences===
Unicode version 3.2 (published in 2002) introduced [[Variant form (Unicode)|variation selectors]] as an encoding mechanism to represent particular glyph forms for characters.<ref>{{cite web |url=https://www.unicode.org/reports/tr28/tr28-3.html |title=Unicode Standard Annex #28, Unicode 3.2 |website=www.unicode.org |date=2002-03-27 |access-date=2017-04-22}}</ref> Unicode did not, however, specify how text renderers should support these sequences. In late 2007, variation sequences for the Adobe-Japan1 collection were registered in the Unicode Ideographic Database,<ref>{{cite web |url=https://www.unicode.org/ivd/ |title=Ideographic Variation Database |website=www.unicode.org |access-date=2017-04-22}}</ref> leading to a real need for an OpenType solution. This resulted in development of the <code>cmap</code> subtable Format 14, which was introduced in OpenType version 1.5.<ref name=ots-changes>{{cite web |url=https://learn.microsoft.com/en-us/typography/opentype/spec/changes |title=OpenType Specification Change Log |department=Microsoft Typography |website=[[Microsoft Learn]] |access-date=2024-04-13}}</ref>

===Color fonts===
{{redirect-distinguish|Color font|Text color}}

Unicode version 6.0 introduced [[emoji]] encoded as characters into Unicode in October 2010.<ref>{{cite web |url=https://www.unicode.org/versions/Unicode6.0.0/ |title=Unicode 6.0.0 |website=www.unicode.org |date=2010-10-11 |access-date=April 22, 2017}}</ref> Several companies quickly acted to add support for Unicode emoji in their products. Since Unicode emoji are handled as text, and since color is an essential aspect of the emoji experience, this led to a need to create mechanisms for displaying multicolor glyphs.

Apple, Google and Microsoft independently developed different color-font solutions for use in [[OS X]], [[iOS]], [[Android (operating system)|Android]] and [[Windows]]. 

* OpenType and OFF already had support for monochrome bitmap glyph, so Google proposed that OFF be extended to allow for color bitmaps. Apple adopted this approach but declined to participate in extending the ISO standard. As a result, Apple added the <code>sbix</code> table to their TrueType format in OS X 10.7,<ref>{{cite web |url=https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6sbix.html |title=The 'sbix' table |website=developer.apple.com |access-date=April 22, 2017}}</ref> while Google proposed addition of the <code>CBDT</code> and <code>CBLC</code> tables to OFF.
* Microsoft adopted a different approach than color bitmaps. Noting existing practice on the Web of layering glyphs of different color on top of one another to create multi-colored elements such as icons, Microsoft proposed a new <code>COLR</code> table to map a glyph into a set of glyphs that are layered, and a <code>CPAL</code> table to define the colors.
* Adobe and Mozilla proposed adding a new <code>SVG</code> table that can represent multi-color glyphs using [[SVG|Scalable Vector Graphics]].

These proposals were all incorporated into the third edition of OFF (ISO/IEC 14496-22:2015).<ref>{{cite web |url=https://www.iso.org/standard/66391.html |title=ISO/IEC 14496-22:2015 Information technology -- Coding of audio-visual objects -- Part 22: Open Font Format |date=October 2015 |access-date=2017-04-22}}</ref> Microsoft added <code>CBDT</code>, <code>CBLC</code>, <code>COLR</code>, <code>CPAL</code>, and <code>SVG</code> tables to OpenType version 1.7,<ref name=ots-changes /> and the <code>sbix</code> table in OpenType version 1.8.<ref name=ots-changes /> Microsoft implemented support for all of the different color formats in [[Windows 10 version 1607]] ("Anniversary Update").<ref>{{cite web |url=https://learn.microsoft.com/en-us/windows/win32/directwrite/what-s-new-in-directwrite-for-windows-8-consumer-preview#windows-10-anniversary-update |title=What's new in DirectWrite § Windows 10 Anniversary Update |department=[[DirectWrite]] |website=[[Microsoft Learn]] |date=4 October 2021 |access-date=2024-04-13}}</ref> 

OpenType 1.9 introduced a second version of the <code>COLR</code> table that adds additional graphics capabilities.<ref name=ots-changes /> Google originally proposed the enhanced version and jointly developed it with Microsoft. The enhanced graphic capabilities include support for three types of gradients, [[Affine transformation | affine transformations]], [[Alpha compositing | compositing]] and [[Blend modes | blending modes]], and custom re-usable components.<ref name=ots-colr>{{cite web |url=https://learn.microsoft.com/en-us/typography/opentype/spec/colr |title=COLR — Color Table |department=Microsoft Typography |website=[[Microsoft Learn]] |access-date=2024-04-13}}</ref> These enhancements give the <code>COLR</code> table all of the graphic capabilities of the <code>SVG</code> table except stroking. They also add compositing and blending modes, support for which is considered optional for the <code>SVG</code> table (as these are implemented in SVG as filter effects).<ref name=ots-svg>{{cite web |url=https://learn.microsoft.com/en-us/typography/opentype/spec/svg |title=SVG — The SVG (Scalable Vector Graphics) Table |department=Microsoft Typography |website=[[Microsoft Learn]] |access-date=2024-04-13}}</ref> In addition, the enhancements to the <code>COLR</code> table are integrated with OpenType Font Variations, which is not possible with the <code>SVG</code> table. The enhanced <code>COLR</code> table is supported in the [[Chromium (web browser) |Chromium browser engine]] as of version 98.<ref>{{cite web |url=https://chromestatus.com/feature/5638148514119680 |title=Feature: COLRv1 Color Gradient Vector Fonts |access-date=2021-12-10}}</ref>

===Collections===

Since at least version 1.4, the OpenType specification had supported "TrueType Collections", a feature of the format that allows multiple fonts to be stored in a single file. Such a format is useful for distributing an entire [[typeface]] (font family) in just one file.

By combining related fonts into a single file, font tables that are identical can be shared, thereby allowing for more efficient storage. Also, individual fonts have a glyph-count limit of 65,535 glyphs, and a Collection file provides a "gap mode" mechanism for overcoming this limit in a single font file. (Each font within the collection still has the 65,535 limit, however.) A TrueType Collection file would typically have a file extension of ".ttc".

However, the specification only described collection files being used in conjunction with glyphs that are represented as TrueType outlines or as bitmaps. The potential existed to provide the same storage and glyph-count benefits to fonts that use CFF-format glyphs (.otf extension). But the specification did not explicitly allow for that.

In 2014, Adobe announced the creation of OpenType Collections (OTCs), a Collection font file that combines fonts that use CFF-format glyphs.<ref>{{cite web|url=https://blogs.adobe.com/CCJKType/2014/01/otc.html |title=Introducing & Building OpenType Collections (OTCs) |website=Blogs.adobe.com |date=2014-01-27 |access-date=2017-01-19}}</ref> This provided significant storage benefits for [[CJK characters|CJK]] fonts that Adobe and Google were jointly developing. For example, the [[Noto fonts]] CJK OTC is ~10 MB smaller than the sum of the four separate OTFs of which it is composed.<ref>{{cite web|url=https://www.google.com/get/noto/help/cjk/ |title=Noto Sans CJK – Google Noto Fonts |website=Google.com |access-date=2017-01-19}}</ref> The use of a Collection also allowed for combining a very large number of glyphs into a single file, as would be needed for a pan-CJK font.<ref>{{cite web|url=https://lwn.net/Articles/613284/ |title=Google and Adobe's pan-CJK open font |website=Lwn.net |access-date=2017-01-19}}</ref>

Explicit support for Collections with CFF-format glyphs was incorporated into the OpenType specification in version 1.8.<ref name=ots-changes /> To reflect this more-inclusive applicability, the term "OpenType Collection" was adopted, superseding "TrueType Collection".

=== Font Variations ===
{{See also|Variable fonts}}
On September 14, 2016, Microsoft announced the release of OpenType version 1.8. This announcement was made together with Adobe, Apple, and Google at the [[ATypI]] conference in Warsaw.<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/M-vdFRtcZU0 Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20170811192129/https://www.youtube.com/watch?v=M-vdFRtcZU0&feature=youtu.be Wayback Machine]{{cbignore}}: {{cite web |url=https://www.youtube.com/watch?v=M-vdFRtcZU0 |title=Special OpenType Session |website=[[YouTube]] |date=2016-09-14 |access-date=2017-04-22}}{{cbignore}}</ref> OpenType version 1.8 introduced "OpenType Font Variations", which adds mechanisms that allow a single font to support many design variations.<ref>{{cite web |url=https://medium.com/@tiro/https-medium-com-tiro-introducing-opentype-variable-fonts-12ba6cd2369 |title=Introducing OpenType Variable Fonts |author=John Hudson |access-date=2017-04-22}}</ref> Fonts that use these mechanisms are commonly referred to as "[[OpenType variable fonts|Variable fonts]]".

OpenType Font Variations re-introduces techniques that were previously developed by Apple in [[Apple Advanced Typography|TrueType GX]], and by Adobe in [[Multiple master fonts|Multiple Master fonts]]. The common idea of these formats is that a single font includes data to describe multiple variations of a glyph outline (sometimes referred to as "masters"), and that at text-display time, the font rasterizer is able to interpolate or "blend" these variations to derive a continuous range of additional outline variations.<ref name=ots-var>{{cite web |url=https://learn.microsoft.com/en-us/typography/opentype/spec/otvaroverview |title=OpenType Font Variations Overview |department=Microsoft Typography |website=[[Microsoft Learn]] |access-date=2024-04-13}}</ref>

The concept of fully parametric fonts had been explored in a more general way by [[Donald Knuth|Donald E. Knuth]] in the [[Metafont|METAFONT]] system, introduced in 1978.<ref>Knuth, Donald E. Mathematical typography. Bull. Amer. Math. Soc. (N.S.) 1 (1979), no. 2, 337--372.https://projecteuclid.org/euclid.bams/1183544082</ref> That system and its successors were never widely adopted by professional type designers or commercial software systems.<ref>CSTUG, Charles University, Prague, March 1996, Questions and Answers with Prof. Donald E. Knuth, reproduced in TUGboat '''17 (4)''' (1996), 355–67. Citation is from page 361. Available online at http://www.tug.org/TUGboat/Articles/tb17-4/tb53knuc.pdf</ref> TrueType GX and Multiple Master formats, OpenType Font Variations' direct predecessors, were introduced in the 1990s, but were not widely adopted, either. Adobe later abandoned support for the Multiple Master format.<ref>{{Cite web |url=https://blog.typekit.com/2014/07/30/the-adobe-originals-silver-anniversary-story-how-the-originals-endured-in-an-ever-changing-industry/ |title=The Adobe Originals Silver Anniversary Story: How the Originals endured in an ever-changing industry |author=Tamye Riggs |date=2014-07-30 |access-date=2017-04-22}}</ref> This has led to questions as to whether a re-introduction of similar technology could succeed. By 2016, however, the industry landscape had changed in several respects. In particular, emergence of Web fonts and of mobile devices had created interest in [[Responsive web design|responsive design]] and in seeking ways to deliver more type variants in a size-efficient format. Also, whereas the 1990s was an era of aggressive competition in font technology, often referred to as "the font wars",<ref>{{Cite web |last=Shimada |first=James |date=2006-12-06 |url=https://courses.cs.washington.edu/courses/csep590/06au/projects/font-wars.pdf |title=The Font Wars |access-date=2021-12-14}}</ref><ref>{{Cite web |url=https://www.britannica.com/topic/Adobe-Systems-Incorporated#ref663628 |title=Adobe Inc. |website=[[Encyclopædia_Britannica|Britannica]] |at=Font Wars |access-date=2022-04-10}}</ref><ref>{{Cite book |last=Cringely |first=Robert X. |author-link=Robert X. Cringely |date=1996 |title=[[Accidental Empires]] |edition=Revised and updated |publisher=[[Penguin Books]] |chapter=Font Wars |chapter-url=https://www.cringely.com/2013/03/14/accidental-empires-chapter-11-font-wars/ |pages=209–229 |isbn=0-14-025826-4}}</ref> OpenType Font Variations was developed in a collaborative manner involving several major vendors.<ref>{{Cite web |url=https://www.pastemagazine.com/articles/2017/01/the-font-wars.html |title=The Font Wars |author=David Lemon |date=2017-01-27 |access-date=2017-04-22}}</ref>

Font Variations is integrated into OpenType 1.8 in a comprehensive manner, allowing most previously-existing capabilities to be used in combination with variations. In particular, variations are supported for both TrueType or CFF glyph outlines, for TrueType hinting, and also for the OpenType Layout mechanisms. The only parts of OpenType for which variations are not supported but might potentially be useful are the 'SVG ' table for color glyphs, and the MATH table for layout of mathematical formulas. The 'SVG ' table uses embedded XML documents, and no enhancement for variation of graphic elements within the SVG documents has been proposed. However, enhancement to the COLR table in OpenType 1.9 has provided a vector format for color glyphs with support for variations.<ref name=ots-colr-vars>{{Cite web |url=https://learn.microsoft.com/en-us/typography/opentype/spec/colr#colr-table-and-opentype-font-variations |title=COLR — Color Table § COLR table and OpenType Font Variations |department=Microsoft Typography |website=[[Microsoft Learn]] |access-date=2024-04-13}}</ref>

OpenType 1.8 made use of tables originally defined by Apple for TrueType GX (the avar, cvar, fvar and gvar tables). It also introduced several new tables, including a new table for version 2 of the CFF format (CFF2), and other new tables or additions to existing tables to integrate variations into other parts of the font format (the HVAR, MVAR, STAT and VVAR tables; additions to the BASE, GDEF and name tables).<ref name=ots-changes />