Some movies don't go down in history for their plot or overall quality, but because they managed to teach the audience something that defies logic and the senses. There are several cases that fit this condition, but one of the most widely known is "Sh! The Octopus", a 1937 film that presents a real-time transformation worthy of any CGI platform. The best part is that the trick is quite easy to reproduce today, as long as you decide to film in black and white…
A couple of months ago we talked about the main techniques used by the film world to miniaturizing characters in certain movies. At the same time, there were developments that aimed not to showcase tricks but to improve the visual quality of each film, such as Technicolor. As new resources appeared and costs dropped, the number of projects with special effects continued to increase, leaving audiences astonished even with the limitations of that era. In fact, some of those limitations were critical to the proper functioning of a visual trick. One of the most striking examples is found in the transformation in "Sh! The Octopus", from 1937.
The Trick Behind the Transformation
First of all, I must apologize for the massive spoiler if someone planned to watch this movie, and secondly, the year of its creation is indeed 1937. So how is it possible that a character transforms in front of the camera in real time without digitalization or mysterious cuts? As mentioned above, the use of black and white is fundamental to the execution of the trick, but in the background it depends on filters, lights, and color. Its creator was Karl Struss, one of the pioneers of 3D cinema, who applied it in the 1925 adaptation of Ben-Hur, in the lepers scene. However, Struss managed to perfect his trick in "Dr. Jekyll & Mr. Hyde" from 1931.
Basically, the actor receives special makeup of a specific color (blue or red) exaggerating shadows and contours, and by placing a filter in front of the lens or lighting his face with a light of the same color, that makeup becomes "invisible". When the filter is removed or the opposite light is applied (say, blue light on red makeup), the contrast is immediate, presenting the transformation. A more "modern" example that does not rely on black-and-white filming but shares a similar mechanism is the video "Figure It Out" by Royal Blood, which swaps red and blue filters depending on the scene.
