Content deleted Content added
fixed misclick |
Why someone deleted the paragraph "HEIC: HEVC in HEIF"? See Special:PermanentLink/1258896680 |
||
Line 91:
{{anchor|HEIC}}{{anchor|HEVC}}
=== HEIC: HEVC in HEIF ===
[[High Efficiency Video Coding]] (HEVC, ITU-T H.265)<ref>{{cite web|url=https://tidbits.com/2020/06/26/what-the-heic-apples-highly-compressed-image-format-still-confuses/|title=What the HEIC? Apple's Highly Compressed Image Format Still Confuses|publisher=TidBITS|first=Glenn|last=Fleishman|date=26 June 2020|access-date=28 June 2020|archive-date=28 June 2020|archive-url=https://web.archive.org/web/20200628103743/https://tidbits.com/2020/06/26/what-the-heic-apples-highly-compressed-image-format-still-confuses/|url-status=live}}</ref> is an encoding format for graphic data, first standardized in 2013.
It is the primarily used and implied default codec for HEIF as specified in the normative Annex B to ISO/IEC 23008-12 ''HEVC Image File Format''.
While not introduced formally in the standard, the acronym <dfn><abbr title="High-Efficiency Image Codec">HEIC</abbr></dfn> (High-Efficiency Image Codec) is used as a ''brand'' and in the MIME subtypes <code>image/heic</code> and <code>image/heic-sequence</code>. If the content conforms to certain [[HEVC#Profiles|HEVC profiles]], more specific brands can be used: <dfn>HEIX</dfn> for Main 10 of HEVC, <dfn>HEIM</dfn> for (Multiview) Main profile, and <dfn>HEIS</dfn> for (Scalable) Main (10) profile of L-HEVC.
A HEIC photo takes up about half the space of an equivalent quality JPEG file.<ref name=HEVCApril2012I0461>{{cite news |title=On HEVC still picture coding performance |first1=Jani |last1=Lainema |first2=Kemal |last2=Ugur |publisher=JCT-VC |url=http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=5721 |date=2012-04-20 |access-date=2013-01-22}}</ref> The initial HEIF specification already defined the means of storing HEVC-encoded [[Video compression picture types|intra images]] (''i-frames'') and HEVC-encoded image sequences in which [[inter frame|inter prediction]] is applied in a constrained manner.
HEVC<!-- or HEIF? --> image players are required to support rectangular cropping and rotation by one, two, and three quarter-turns. The primary use case for the mandatory support for rotation by 90 degrees is for images where the camera orientation is incorrectly detected or inferred. The rotation requirement makes it possible to manually adjust the orientation of a still image or an image sequence without needing to re-encode it. Cropping enables the image to be re-framed without re-encoding. The HEVC file format also includes the option to store pre-derived images.<ref name="Nokia">{{cite web |url=https://nokiatech.github.io/heif/technical.html |title=HEIF Technical Information |subject=High Efficiency Image File Format |publisher=Nokia |website=nokiatech.github.io |at=Images in HEIF Files |access-date=2018-02-01 |archive-date=2018-02-01 |archive-url=https://web.archive.org/web/20180201152802/http://nokiatech.github.io/heif/technical.html |url-status=live }}</ref>
Samples in image sequence tracks must be either intra-coded images or inter-picture predicted images with reference to only intra-coded images. These constraints of inter-picture prediction reduce the decoding latency for accessing any particular image within a HEVC image sequence track.
The ''.heic'' and ''.heics'' file name extensions are conventionally used for HEVC-coded HEIF files.<ref name="WWDC2017 511">{{cite web |url=https://developer.apple.com/videos/play/wwdc2017/511 |title=Working with HEIF and HEVC - WWDC 2017 - Videos |website=Apple Developer |access-date=2019-01-19 |archive-date=2019-01-20 |archive-url=https://web.archive.org/web/20190120194504/https://developer.apple.com/videos/play/wwdc2017/511 |url-status=live }}</ref> Apple products, for instance,<ref name="WWDC2017 513">{{cite web |url=https://developer.apple.com/videos/play/wwdc2017/513 |title=High Efficiency Image File Format |time=0:09:26 |publisher=[[Apple Inc.|Apple]] |date=June 2017 |access-date=2017-11-22 |archive-date=2017-12-01 |archive-url=https://web.archive.org/web/20171201032622/https://developer.apple.com/videos/play/wwdc2017/513 |url-status=live }}</ref> will only produce files with these extensions, which indicate clearly that the data went through HEVC encoding.<ref name="CNET">{{cite web |url=https://www.cnet.com/news/apple-ios-boosts-heif-photos-over-jpeg-wwdc |title=How Apple is squeezing more photos into your iPhone – FAQ: Apple's newest iPhone software attempts to move the world out of the JPEG era. |publisher=[[CNET]] |first=Stephen |last=Shankland |date=June 16, 2017 |access-date=2017-11-21 |archive-date=2017-11-16 |archive-url=https://web.archive.org/web/20171116181530/https://www.cnet.com/news/apple-ios-boosts-heif-photos-over-jpeg-wwdc/ |url-status=live }}</ref>
{{anchor|AVCI}}{{anchor|AVC}}
| |||