Colour Correction with Curves
Written by Justin Tomchuk
Amateur filmmakers tend to overlook the impact colour correction can have on a video. Generally, when a video is shot, the videographer will do their best to have a sharp image, clear colours and good exposure. Colour correction in post production picks up from there.
Most raw video will have a dull look to it unless a lot of effort went into lighting, camera tweaking, lenses etc. Filmmakers with low budgets and short time schedules tend to compromise such things. Too often from amateur filmmakers colour correction in post is overlooked.
This is a basic guide to demonstrate the power of the curves tool that decent editing programs have. It will show that you do not need to spend a fortune on special software and plugins to have your video look well.
A basic example of colour correction with curves. As shown, the RGB curve looks like a very slight "S". It has made the image brighter, and darker and generally clearer. At the very least this should be applied to all videos that require it.
This one combines the s curve with a tapered one for the blue channel. This made the pure whites slightly yellow and the shadows have a blue tint. It makes the video look more like real film minus the depth of field and other film characteristics.
Sometimes for style reasons you might want the video look like old film. The example above shows how the curves can make a plain video look old and faded, like its from the 70s. You can see that the RGB curves have been modified and the single red and blue curves have been changed as well.
The blue channels curves looks like they have been shortened or flattened from the corners it regularly are. The arrangement of the blue curve makes the whites look yellow and the blacks look bluish. This makes the video look faded.
The red curve makes the bluish shadows slightly purple. You can see in the example that there are no pure whites or pure blacks much like a faded film from the 70s. You can change around the curves however you want though; to have the colour the way you want it to look.
You can use the features on your camera to make your video black and white or you can make it black and white in post. If you are using a decent camera, the black and white feature on it will capture light differently from regular colour to make the subjects sharper and with more contrast.
If not, the black and white video will look flat. If you use post production to make your video black and white be sure to add contrast or modify the RGB curves as well. Modifying the RGB curves will give you more control than just contrast.
As you can see the value range is much greater in the corrected image than the desaturated one.
So, it has been shown that colour correcting will make a huge positive impact on your video's appearance. While it may not be a priority and while set design, camera work and cinemetography play huge role's in making your video look good, colour correction will make all your hard work look professional and clean and can give your film an interesting feel.