Color correction can be a pain – little wonder that colorists make the big bucks! But by doing a little arithmetic you can get rid of any color cast quickly and accurately.
There are 5 easy steps to follow…
1) Identify an area in your image that should be a neutral color – typically a shadow on a neutral color. This helps to determine the color cast of your footage.
2) Hover your cursor over the shadow and write down the color channel (RGB) information, which can be located in the Info Panel, located in the upper right corner of the Standard Workspace. Save this information for later.
3) Determine the color channel with the highest color value, and divide that into the maximum value for the color bit depth of the project. (255 for an 8bpc project). We’ll call the resulting value the Color Correction Factor
4) Multiply the remaining two color channel values by the Color Correction Factor
5) Enter the resulting numbers as the Color (Red, Green, or Blue) Input White values.
Voila! Your footage should now have an accurate color correction. The only adjustments necessary are for contrast by adjusting the RGB composite input black and white amounts, as well as adjusting the RGB composite gamma value. Let’s examine how this effect works using a piece of footage that I shot this spring…
While viewing a piece of footage that I shot of the yoshino cherry in my backyard (hence my company’s name), I noticed a very slight red cast.
So, I sampled the values from a small hotspot in the background, about a third of the way down on the left hand side. The sampled values that I got were R=166, B=152, G=155. Since the R value was the hottest of the three, I divided 166 into 255 and ended up with 1.54 as my Color Correction Factor. I multiplied the Green and Blue values by the Color Correction Factor and ended up with 234.1 and 238.7, respectively. I then applied Effects>Color Correction>Levels (Individual Controls) to my footage and entered those two values for the Input White for the Green and Blue channels…
While the red cast is pleasant on a cherry tree, the petals are practically white, except for the fringing on the inside near the stamens, giving the trees a vibrant pink when viewed from far away. Since I wanted an accurate and consistent color in all of my footage from that day, I made the choice to stick with the color correction, rather than leave the red cast in the footage. That way I didn’t have to worry about applying a separate instance of SA Color Finesse 3 when I imported my video back into After Effects from Premiere Pro via the Adobe Dynamic Link.
The final step to get the footage looking just right was to add some contrast with the composite input white and black values and gamma adjustment. Since there was plenty of luminance on the upper end, I only raised the black input value and lowered the gamma amount a touch and came up with the following:
Admittedly, this method is not fool proof, but it can usually get you pretty close to a desirable color correction. The only exception that I’ve found thus far is a strong color cast, specifically yellow. Even a moderate blue, red, or green cast can be cancelled with passable results using this method. As with any footage, be careful of how strongly a method is applied, as noise and other artifacts can enter the process resulting in undesirable and unpredictable consequences.
Hopefully this method informs your work as you composite your footage together in new and creative ways!