The Thief of Bagdad: The first film to use the chroma key process

The blue screen was developed in the 1930s and were used to create special effects for The Thief of Bagdad. 

The credit for development of the blue screen is given to Larry Butler, who won the Academy Award for Special Effects for the Thief of Baghdad in 1940. He had invented the blue screen along with the traveling matte (photography and special effects filmmaking to combine two or more image elements into a single, final image) technique in order to achieve the visual effects which were unprecedented in 1940. He was also the first special effects man to have created these effects in Technicolor, which was in its infancy at the time.

The Thief of Bagdad released long back in 1940 is considered to be a very important movie in Hollywood purely because of the fact that the amount of special effects used in the film was by far more than that had so long been seen and the quality of these also made it a very a wonderful experience for both the audience and the critics. A few years back, with the release of Flying down to Rio, there was widespread awe for the special effects that were used in it, but with The Thief of Bagdad, it was whole different thing with a lot more percentage of special effects used in it.

Before the movie was released, the use of special effects was kind of clichéd and mainly the big production houses could afford using the technology required to create a good visual effect. But this film brought it down to the level where every production house in Hollywood could have access to the technology required to create the perfect illusion. Every special effects director in Hollywood would say the same thing, that the inspiration behind them going into that division was the movie The Thief of Bagdad and the brilliance that it achieved with the limited resources that were available back in those days.

The film was nominated for the Academy Awards in the three fields of cinematography, special effects and art direction and it swept all three categories and this bears testimony to the quality it was able to generate through its special effects. Before this film came about, the effects that were used in other films looked very bad and almost like a joke but with the use of the travelling matte technology as well as the newly developed technology of blue screening, The Thief of Bagdad achieved the highest standards at that time and according to many people, even surpassed them with relative ease. Larry Butler, who won the Oscar for his work in this film developed the blue screen from what it used to be and at one point of time, it was what most special effects supervisors swore by.

Technicolor was almost an infant at that time and Larry Butler created a technique that would suit it perfectly using the travelling matte and the blue screen in order to create the perfect illusion for it and hence, changed the face of modern cinema.