YJK

{{Short description|Color space implemented by the Yamaha V9958 graphic chip}}

File:Rgb vs YJK.png

YJK{{Cite web |last=MSX Licensing Corporation |date=2022 |title=The YJK screen modes |url=http://map.grauw.nl/articles/yjk/ |website=MSX Assembly Page}}{{Cite book |last=Niemietz |first=Ricardo Cancho |url=http://rs.gr8bit.ru/Documentation/Issues-on-YJK-colour-model-implemented-in-Yamaha-V9958-VDP-chip.pdf |title=Issues on YJK colour model implemented in Yamaha V9958 VDP chip |year=2014}}{{Cite web |title=VCFe Vortrag vom 2016.04.30 - Homecomputer und Spielkonsolen - Videoarchitekturen als visuelles Medium |url=http://neil.franklin.ch/Articles/20160430_VCFe_Video_als_Medium.html |access-date=2022-11-13 |website=neil.franklin.ch}} is a proprietary color space implemented by the Yamaha V9958{{Cite book |url=https://books.google.com/books?id=8RwSAQAAMAAJ&dq=%22Yamaha+V9958%22+-wikipedia&pg=PA3984 |title=IC Master |date=2001 |publisher=United Technical Publications |language=en}}{{Cite thesis |title=Arqueología informática: los ordenadores MSX en los inicios de la microinformática doméstica |url=https://riunet.upv.es/handle/10251/70909 |publisher=Universitat Politècnica de València |date=2016-10-03 |degree=Proyecto/Trabajo fin de carrera/grado |first=Sergio |last=Martín Sesma|hdl=10251/70909 |hdl-access=free }}{{Cite web |last=Redazione |date=2008-10-20 |title=MSX - Vari Costruttori- 1983 |url=https://www.cyberludus.com/2008/10/msx-vari-costruttori-1983/ |access-date=2022-11-13 |website=CyberLudus.com |language=it-IT}} graphic chip on MSX2+ computers.{{Cite web |date=1988 |title=V9958 MSX-VIDEO TECHNICAL DATA BOOK |url=http://map.grauw.nl/resources/video/yamaha_v9958_ocr.pdf}}{{Cite journal |last=Alex |first=Wulms |date=1995 |title=Schermen op MSX - De 2+ schermen |url=http://www.msxarchive.nl/pub/msx/mirrors/hanso/hwdoityourself/msxplus.pdf |journal=MSX Computer & Club Magazine |issue=72}} It has the advantage of encoding images by implementing less resolution for color information than for brightness, taking advantage of the human visual systems' lower acuity for color differences.{{cite book |author=S. Winkler, C. J. van den Branden Lambrecht, and M. Kunt |title=Vision models and applications to image and video processing |publisher=Springer |year=2001 |isbn=978-0-7923-7422-0 |editor=Christian J. van den Branden Lambrecht |page=209 |chapter=Vision and Video: Models and Applications |chapter-url=https://books.google.com/books?id=_s2BlAeR66YC&pg=PA209}} This saves memory, transmission and computing power.File:YJK example image.pngYJK is composed of three components: $Y$, $J$ and $K$. $Y$ is similar to luminance (but computed differently), $J$ and $K$ are the chrominance components (representing the red and green color differences). The $Y$ component is a 5-bit value (0 to 31), specified for each individual pixel. File:Rgb.pngThe $J$ and $K$ components are stored together in 6 bits (-32 to 31) and shared between 4 nearby pixels (4:2:0 chroma sub-sampling).{{Cite web|url=http://map.grauw.nl/articles/yjk/|title=The YJK screen modes|website=map.grauw.nl}}{{Cite book |last=Silveira |first=Marcelo |url=http://marmsx.msxall.com/artigos/sc12en.pdf |title=MSX 2+ Colors |year=2017}}{{Cite web |last=Nunes |first=Giovanni |title=Edição de imagens num MSX2+/MSX turbo R |url=https://retropolis.com.br/2015/06/08/edicao-de-imagens-num-msx2msx-turbo-r/ |website=retropolis.com.br|date=8 June 2015 }}

This arrangement allows for the encoding of 19,268 different colors.

While conceptually similar to YUV, chroma sampling, numerical relationship between the components, and transformation to and from RGB are different in YJK.