Color grading techniques in photography became popular in the world of photography along with the popularity of techniques / cinematic effects on still images. This cinematic effect is intended to create the impression of a still image being seen as a scene taken from the movie. Because to create a mood and appearance in the movie using the term color grading, then this term was so carried and popular in photography still.
Color grading or color grade is actually a common thing done since a long time in the world of both photo and movie media. The goal is to improve the color (color correction) to fit the original or to realize the effect of artisitik colors in accordance with the wishes of the maker. The process can be done electronically (telecine), using chemicals (color timing) or digitally popular today.
You can see how the colors displayed are not natural. But this does not matter because the audience does not have enough time to respond to it "seriously" because the continuity factor of the movie will bring the audience to the scene or the story that is running. Thus the audience is conditioned by the mood, style or look of the movie created by the creator.
The process of extreme color grading as in the movie of course does not mean it should not be applied to still images. The final decision remains with the creator in terms of the artistic approach of his work.
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