Question: Which American visual effects supervisor at Industrial Light and Magic is the original creators of Adobe Photoshop?

Context paragraphs:
Christopher Townsend: Christopher Townsend is a visual effects supervisor.  He has worked in the visual effects industry for over 20 years.  For over a decade, he was an artist and supervisor at Industrial Light and Magic, and in 2007 became a freelance visual effects supervisor.  He worked on "Journey to the Center of the Earth", the first ever stereoscopic motion picture shot and released digitally, "Wolverine", "Ninja Assassin", "" and "".  He was nominated for a BAFTA and an Academy Award for Best Visual Effects for his work on "Iron Man 3", oversaw nearly 3000 shots on "" and was the overall supervisor for "Guardians of the Galaxy Vol.  2".  In 2015 he was given an Honorary Doctor of Arts degree by his alma mater, Coventry University.

Richard Bluff: Richard Bluff is an English special effects supervisor.  Known for his works in Disney's visual effects company Industrial Light & Magic (ILM) as a digital matte artist and visual effects supervisor in acclaimed films such as "" (2005), "The Island" (2005), "Transformers" (2007-11), "Indiana Jones and the Kingdom of the Crystal Skull" (2008), "Star Trek" (2009), "Avatar" (2009), "The Avengers" (2012), "Cloud Atlas" (2012) "Pacific Rim" (2013), "The Big Short" (2015) and "Doctor Strange" (2016), for which he received an Academy Award for Best Visual Effects nomination at the 89th Academy Awards.  He previously worked at Blur Studio as digital artist.

John Knoll: John Knoll (born October 6, 1962) is an American visual effects supervisor and chief creative officer (CCO) at Industrial Light & Magic (ILM).  One of the original creators of Adobe Photoshop (along with his brother, Thomas Knoll), he has also worked as visual effects supervisor on the "Star Wars" prequels and the 1997 special editions of the original trilogy.  He also served as ILM's visual effects supervisor for "Star Trek Generations" and "", as well as the "" series.  Along with Hal Hickel, Charles Gibson and Allen Hall, Knoll and the trios work on "" earned them the Academy Award for Best Visual Effects.

Greg Butler (visual effects supervisor): Gregory S. Butler (August 18, 1971, Suffield, Connecticut) is a visual effects supervisor.  He graduated from Suffield High School in 1989 and afterwards entered Hampshire College.  Despite his initial plans to study history, a work-study job with the audiovisual equipment in the library made him interested in film production.  Butler graduated in 1993 with a major in film, television and theater design.  Afterwards he moved to California to work for Industrial Light and Magic for 9 months, where after intern work he managed to become an assistant in the effects department, starting with assistant credits in "The Mask" and "Forrest Gump".  Following a job at Rocket Science Games until the company's bankruptcy in 1996, Butler went to Tippett Studio and did effects work in "Starship Troopers" and "My Favorite Martian", rising up to a technical director job, and Cinesite for "Practical Magic".  While reluctant at the requirement of moving to New Zealand, Butler was convinced by his writer-actor brother Jared to jump at the opportunity of working for Weta Digital in "The Lord of the Rings".  His biggest achievement was working in the creation of Gollum.  Butler also worked as a computer graphics supervisor on "I, Robot" before an invitation to work as an effects supervisor for the Moving Picture Company, in London.  He continues on MPC, but is now on the Vancouver office.  On January 24, 2012, he was nominated for an Academy Award for "".

Ken Ralston: Kenneth "Ken" Ralston (born 1954) is an American visual effects artist, currently the Visual Effect Supervisor and Creative Head at Sony Pictures Imageworks.  Ralston began his career at the seminal commercial animation and visual effects company, Cascade Pictures in Hollywood, where he worked on over 150 advertising campaigns in the early 1970s.  In 1976, he was hired at Industrial Light & Magic by Dennis Muren to help George Lucas create the effects for "Star Wars".  He remained in ILM for 20 years before joining Sony Pictures Imageworks as president.  Ralston is best known for his work in the films of Robert Zemeckis.

Thomas Knoll: Thomas Knoll (born April 14, 1960) is an American software engineer who created Adobe Photoshop.  He initiated the development of image processing routines in 1988.  After Tom created the first core routines, he showed them to his brother, John Knoll, who worked at Industrial Light and Magic.  John liked what he saw, suggested new features, and encouraged Tom to bundle them into a package with a graphical user interface.  In 1989, John successfully sold the program to Adobe Systems which brought it out as Photoshop.

Harrison Ellenshaw: Harrison Ellenshaw (born Peter Ellenshaw, July 20, 1945 in Harrisburg, Pennsylvania) is an American matte painter, following his British-born father Peter Ellenshaw.  He started his career at Walt Disney Studios.  He later joined George Lucas's effects studio Industrial Light and Magic (ILM), where he produced many of the matte visual effects backgrounds for the films "Star Wars" (1977) and "The Empire Strikes Back" (1980).  He then returned to Disney to work on the film "Dick Tracy" (1990), and eventually headed Disney Studio's effects department, Buena Vista Visual Effects (BVVE).  He was also visual effects supervisor for "Tron" (1982), where he had the distinction of being the first person to have that credit in a film.

Specular International: Specular International was a company founded by Dennis Chen and Adam Lavine in 1990.  Specular created and distributed several software products, the most popular of which was Infini-D, an integrated 3D modeling, rendering, and animation software product that specialized in 3D effects such.  Infini-D was part of a larger trend in bringing 3D technologies once only available in powerful workstations to a wider personal computer audience.  Other Specular products included Collage, a high-resolution Adobe Photoshop compositing companion product, and BackBurner, a distributed rendering system that used multiple Apple Macintosh computers on a network or over the internet to render computationally intensive 3D animations.  Many Specular employees joined Adobe Systems, and worked on products including Adobe Photoshop, Adobe After Effects, and Adobe Premiere.  Specular merged with MetaTools in 1997 to form MetaCreations.

Adobe Photoshop Lightroom: Adobe Photoshop Lightroom is a photo processor and image organizer developed by Adobe Systems for Windows and macOS.  It allows viewing, organizing and retouching large numbers of digital images.  Lightroom's edits are non-destructive.  Despite sharing its name with Adobe Photoshop, it cannot perform many Photoshop functions such as doctoring (adding, removing or altering the appearance of individual image items), rendering text or 3D objects on images, or modifying individual video frames.  Lightroom is not a file manager like Adobe Bridge.  It cannot operate on files unless they are imported into its database first, and only in recognized image formats.

Industrial Light &amp; Magic: Industrial Light & Magic (ILM) is an American motion picture visual effects company that was founded in May 1975 by George Lucas.  It is a division of the film production company, Lucasfilm, which Lucas founded, and was created when Lucas began production of the film "Star Wars".  It is also the original founder company of the animation studio Pixar.

Supporting paragraphs: John Knoll Industrial Light &amp; Magic
Answer: John Knoll