I believe they use a green screen. They film the background first then with a green screen they tape the players on brooms. then they merge the background with the players. They also have complicated stunts and the actors do sit on broomsticks which is very painful.
Special Effects in movies are either made by the computer or by combining videos.
Combining Videos
Usually if you are combining videos you take a video...i gtg...nvm
Some of the special effects in the Harry Potter and the Philosopher's Stone movie were the Troll and the Centaurs. Most of the creatures are animated and so are some of the magical aspects.
This article by the CG Society gives some answers:
http://features.cgsociety.org/story_custom.php?story_id=4225
With a computer, and very good skills.
I assume you mean in the films. In which case, they use special effects to create the thestrals.
Special effects... Or magic. They're probably going to need to get harry potter in to sort that part out though.
Death, Removal of Soul, Memory Loss
As the title suggests, Harry Potter.
The fourth Harry Potter is Harry Potter and the Goblet of Fire.
They use special effects to create the awesome spells on Harry Potter.
Harry Potter and the Philosopher's Stone.
a movie like Harry Potter is Percy Jackson, because it has a lot of fantasy in it and special effects
Through animation and special effects.
Richard Harris was in two harry potter movies. Harry Potter and the philosophers stone and Harry Potter and the chamber of secrets
Its Actually Called Harry Potter And The Philosophers Stone silly
No , it is all special effects.
Harry Potter and the Philosophers Stone
Harry Potter and the philosophers stone
The names of the book in order are harry potter and the philosophers stone harry potter and the chamber of secrets harry potter and the prisoner of azkaban harry potter and the goblet of fire harry potter and the order of the phoenix harry potter and half blood prince harry potter and the deathly hallows
The 7 books in the Harry Potter series # Harry Potter and the Philosophers Stone # Harry Potter and the Chamber of Secrets # Harry Potter and the Prisoner of Azkaban # Harry Potter and the Goblet of Fire # Harry Potter and the Order of the Phoenix # Harry Potter and the Half Blood Prince # Harry Potter and the Deathly Hallows
the philosophers stone