Visual effects

Visual effects — often abbreviated as VFX — are those elements of a shot which cannot be achieved exclusively by practical means during principal photography. They can be accomplished with the varying techniques of CGI, model work and other techniques. Even practical effects can be used as an element in a "visual effects shot", such as when specially filmed flame or lava effects are later composited into a scene.

For the most part, the starting "canvass" for a VFX is a blue or green screen placed behind actors during principal photography. This solid patch of color an then be removed and replaced with another image. During much of the original series, this was achieved through a process known as color separation overlay, whereby a blue screen would be fed images during the live recording of the shot. Since the TV movie, most of the VFX seen on Doctor Who have been achieved through the use of CGI, a more nuanced approach which allows elements rendered on a computer to be composited into a shot captured during principal photography. As contrasted with CSO work, CGI work is completed exclusively in post-production. For this reason, many no longer consider CSO to be a true visual effect, but rather a "special effect".

The term describes both the title the work and the work itself. Thus The Mill provide VFX and are given the title of "Visual Effects" in the credits of the 2005 series of Doctor Who.

Historical usage
Of the two terms, "visual effects" and "special effects", "visual effects" has been around for much longer in the history of Doctor Who.

Season 4

 * The Evil of the Daleks - Peter Day and Michealjohn Harris

Season 5

 * The Tomb of the Cybermen - Peter Day and Michealjohn Harris
 * The Abominable Snowmen - Ulrich Grosser and Ron Oates
 * The Ice Warriors - Ron Oates and Bernard Wilkie
 * The Web of Fear - Ron Oates
 * Fury from the Deep - Peter Day and Len Hutton
 * The Wheel in Space - Bill King

Season 6

 * The Dominators - Ron Oates
 * The Mind Robber - Jack Kine and Bernard Wilkie
 * The Invasion - Bill King (Trading Post)
 * The Krotons - Bill King (Trading Post)
 * The Seeds of Death - Bill King (Trading Post)
 * The Space Pirates - John Wood
 * The War Games - Michealjohn Harris

Season 7

 * Spearhead from Space - John Horton
 * Doctor Who and the Silurians - Jim Ward
 * The Ambassadors of Death - Peter Day and Ian Scoones
 * Inferno - Len Hutton

Season 8

 * Terror of the Autons - Michealjohn Harris
 * The Mind of Evil - Jim Ward
 * The Claws of Axos - John Horton
 * Colony in Space - Bernard Wilkie
 * The Dæmons - Peter Day

Season 9

 * Day of the Daleks - Jim Ward
 * The Curse of Peladon - Ian Scoones and Bernard Wilkie
 * The Sea Devils - Peter Day
 * The Mutants - John Horton
 * The Time Monster - Michealjohn Harris and Peter Pegrum

Season 10

 * The Three Doctors - Michealjohn Harris and Len Hutton
 * Carnival of Monsters - John Horton
 * Frontier in Space - Rhys Jones and Bernard Wilkie
 * Planet of the Daleks - Clifford Culley
 * The Green Death - Richard Conway, Colin Mapson and Ron Oates

Season 11

 * The Time Warrior - Peter Pegrum and Jim Ward
 * Invasion of the Dinosaurs - Clifford Culley
 * Death to the Daleks - Jim Ward
 * The Monster of Peladon - Peter Day
 * Planet of the Spiders - Bernard Wilkie

Season 12

 * Robot - Clifford Culley
 * The Ark in Space - John Friedlander and Tony Oxley
 * The Sontaran Experiment - John Friedlander and Tony Oxley
 * Genesis of the Daleks - Peter Day
 * Revenge of the Cybermen - Jim Ward

Season 13

 * Terror of the Zygons - John Friedlander and John Horton
 * Planet of Evil - Dave Havard
 * Pyramids of Mars - Ian Scoones
 * The Android Invasion - Len Hutton
 * The Brain of Morbius - John Horton
 * The Seeds of Doom - Richard Conway

Season 14

 * The Masque of Mandragora - Ian Scoones
 * The Hand of Fear - Colin Mapson
 * The Deadly Assassin - Peter Day and Len Hutton
 * The Face of Evil - Mat Irvine
 * The Robots of Death - Richard Conway
 * The Talons of Weng-Chiang - Michealjohn Harris

Season 15

 * Horror of Fang Rock - Peter Pegrum
 * The Invisible Enemy - Tony Harding and Ian Scoones
 * Image of the Fendahl - Colin Mapson
 * The Sun Makers - Peter Day and Peter Logan
 * Underworld - Richard Conway
 * The Invasion of Time - Richard Conway and Colin Mapson

Season 16

 * The Ribos Operation - Dave Havard
 * The Pirate Planet - Colin Mapson
 * The Stones of Blood - Mat Irvine
 * The Androids of Tara - Len Hutton
 * The Power of Kroll - Tony Harding
 * The Armageddon Factor - John Horton

Season 17

 * Destiny of the Daleks - Peter Logan
 * City of Death - Ian Scoones
 * The Creature from the Pit - Mat Irvine
 * Nightmare of Eden - Colin Mapson
 * The Horns of Nimon - Peter Pegrum

Season 18

 * The Leisure Hive - Andrew Lazell
 * Meglos - Steven Drewett
 * Full Circle - John Brace
 * State of Decay - Tony Harding
 * Warriors' Gate - Mat Irvine
 * The Keeper of Traken - Peter Logan
 * Logopolis - John Horton

Season 19

 * Castrovalva - Simon McDonald
 * Four to Doomsday - Mickey Edwards
 * Kinda - Peter Logan
 * The Visitation - Peter Wragg
 * Black Orchid - Eric Alba
 * Earthshock - Steve Bowman
 * Time-Flight - Peter Logan

Season 20

 * Arc of Infinity - Chris Lawson
 * Snakedance - Andrew Lazell
 * Mawdryn Undead - Stuart Brisdon
 * Terminus - Peter Pegrum
 * Enlightenment - Mike Kelt
 * The King's Demons - Tony Harding
 * The Five Doctors - John Brace

Season 21

 * Warriors of the Deep - Mat Irvine
 * The Awakening - Tony Harding
 * Frontios - Dave Havard
 * Resurrection of the Daleks - Peter Wragg
 * Planet of Fire - Chris Lawson
 * The Caves of Androzani - Stuart Brisdon and Jim Francis
 * The Twin Dilemma - Stuart Brisdon

Season 22

 * Attack of the Cybermen - Chris Lawson
 * Vengeance on Varos - Charles Jeanes
 * The Mark of the Rani - David Barton
 * The Two Doctors - Steven Drewett
 * Timelash - Kevin Molloy
 * Revelation of the Daleks - John Brace

Season 23

 * The Trial of a Time Lord
 * The Mysterious Planet - Mike Kelt
 * Mindwarp - Peter Wragg
 * Terror of the Vervoids - Kevin Molloy
 * The Ultimate Foe - Kevin Molloy

Season 24

 * Time and the Rani - Colin Mapson
 * Paradise Towers - Simon Taylor
 * Delta and the Bannermen - Andy McVean
 * Dragonfire - Andy McVean

Season 25

 * Remembrance of the Daleks - Stuart Brisdon
 * The Happiness Patrol - Perry Brahan
 * Silver Nemesis - Perry Brahan
 * The Greatest Show in the Galaxy - Steve Bowman

Season 26

 * Battlefield - Dave Bezkorowajny
 * Ghost Light - Malcolm James
 * The Curse of Fenric - Graham Brown
 * Survival - Malcolm James

Television Movie

 * Doctor Who - Tony Dow and Eric Alba