Much of the magic of cinema is the result of post-production, which is why choosing the right studio for your project is vital for completing your vision the way you intended.

The right post-production and visual effects are what turn a green room in a production studio in Manchester into a grand alien world or a verdant, fantastical paradise. They turn tennis balls into impossible beasts and help take audiences along for the journey.

Even films that are typically praised for their use of practical effects, such as 2015’s Mad Max: Fury Road, extensively relied on subtle uses of CGI and visual effects to add to the astonishing set pieces.

However, as with any tool in the filmmaker’s arsenal, its effectiveness is based on how it contributes to the overall vision of a film, and adding additional effects without due care can spoil particular scenes or even whole projects.

With that in mind, here are three trends in the long history of post-production that have proven controversial more often than not.

Goat Glands

When Al Jolson said “you ain’t heard nothing yet” in 1927 in what was thought to be another silent film, cinematic history changed overnight forever.

Whilst far from the first sound film, The Jazz Singer is the first feature-length “talkie” and completely took Hollywood by surprise and put other studios on the back foot for the rest of the decade.

What they attempted to do in the years following The Jazz Singer was to take other films that had been produced as silent movies and add dialogue or musical numbers to them in post-production to try to replicate the success Warner Bros had had.

The process was called goat-glanding, the infamous surgical treatment for impotence sold by fraudulent doctor John R Brinkley throughout the 1920s and into the 1930s.

Around 100 films became goat gland films, but mercifully, the process ceased by 1930 as the backlog of silent films ran out and the entire film industry opted for sound films.

Colourisation

By itself, colourisation is a tool that can create some very distinctive effects; the pioneering 1982 film Tron uses a form of colourisation to create the unique glowing light effects seen on the computer program characters.

Where it becomes controversial is when colourisation is used to rerelease a film originally shown in black-and-white, and which has made contrast and colour decisions that hurt the overall film when painted over or even distributed in their original shades.

Film critics Gene Siskel and Roger Ebert dedicated a 1987 episode of their At The Movies to what they described as “Hollywood’s New Vandalism”, sharply criticised colourisation more broadly and the then-limitations of digital colourisation in the 1980s.

The wave broke with an attempt by Ted Turner’s Turner Entertainment to colourise Citizen Kane against the wishes of a then-dying Orson Welles. Ultimately, only a minute of the film was colourised before the plan was dropped.

Colourisation, even of old films, can be utilised stylistically, but it ultimately leads to a very different film.

3D Re-Releases

A very similar controversy emerged thanks to the popularity of 2009’s Avatar by James Cameron, which was one of the first major blockbusters to extensively use three-dimensional technology and filming techniques in decades.

Whilst there had been certain one-off special features such as Spy Kids 3-D, Avatar was immediately successful and created a wave of 3D films that would last until the middle of the 2010s.

Some of these films were filmed specifically to be shown in 3D, such as Tron: Legacy. However, many more employed conversion techniques late in production or were outright re-releases retrofitted to include 3D.

This has effects on light fidelity, creates artefacts and often leads to somewhat shallow results, and whilst films are still screened in 3D, it did not become the ubiquitous experience many in the industry expected.