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What is GAMMA? Colour Correction Advice!

When out capturing footage, how many of you use the ‘Standard’ picture style in your camera? Do you shoot ‘Neutral’, ‘Cinestyle’ or ever RAW? It is always interesting to find out, as the workflow and manipulation of the footage is different depending on your input video signal.. Did you burn in your brightness and contrast, or did you give enough dynamic range to push and pull your shadows and highlights when colour correcting and grading in post production?

As I capture my footage on a Canon 60D, it records in compressed .MOV format, which is not great due to the compressed signal. However, by making your image ‘flatter’ or what looks like hazy and grey, you are able to add or remove detail that may have been baked in during acquisition.

A little case study for you, take my footage that I am working on currently. Here is a screenshot of a clip before I took it into Premiere Pro –

post1

I then colour corrected or ‘graded’ the clip using a couple of the video effects built into Premiere Pro, namely the ‘Luma Corrector’ and ‘Three Way Colour Corrector’ to perform the basic exposure and colour balance corrections.

Where using the ‘Luma Corrector’ has its advantages over using the ‘Brightness & Contrast’ or ‘RGB Curves’ effects is that the ‘Luma Corrector’ allows you to adjust the Gamma level of the image. Gamma being a extra luma curve that is added to the image after the sensor captures the data which allows the image to be constantly correctly exposed when played back on old school CRT displays. Now, these displays are not so common these days, but it is still a standard practice to apply a gamma curve to the processed video signal.

The advantage of increasing or reducing the gamma using the ‘Luma Corrector’ is that it removes the ‘flattened’ or neutral look to the image, while still retaining a constant contrast, resulting in a sharp and nicely graded shot. Here is another shot of the Luma Corrector and Three Way Colour Corrector being used on the same clip as above –

post2

I hope this example demonstrates the advantage of capturing your footage a neutral setting to get the most out of your final product!

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About Adam Plowden Videography

Adam Plowden is a videographer and motion graphics artist from Surrey. He graduated with a 1st BSc. Hons in Television and Video Technology, after realizing his creative passion for media. Being a motivated opportunist, he’s had the pleasure of working with many companies and brands producing cinematic immersive videos and media, gaining industry experience, a vast skill set and recognition in the industry; recently winning an honorary membership to the IET and the Engineering Student Award from the IABM.

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