Basic Colour Correction - By Si Cox
Introduction
There is alot to know about colour correcting your film, but over a series of lectures, I’m going to go through some of my techniques, workflows and tools I use on a day to day basis.
In the following steps I’m going to be concentrating on adjusting an image to increase the contrast. This is usually one of the first steps you’ll take when starting out on your colour correction. I’ll be making my correction using Apple Color, but many NLE’s have similar tools to do the same job. As you do more and more colour correction you might find other ways to do the same task, which is fine, its all about finding a workflow which is best suited to you.
An image is broken down into 3 tonal ranges. Shadows, Midtones & Highlights. We will be adjusting each one to adjust our contrast, starting with the shadows (or blacks, pedestal, lift - various names, same meaning), then working on the highlights (whites, gain) then finally the midtones (gamma, mids).
In your chosen application, either navigate to the controls or add a 3 way color corrector to your footage. You should now see 3 coloured wheels, each coupled with a brightness control either around the edge or along side. This is what you’ll be using to make your corrections.
Once you have you image to be corrected open and ready, start by looking at the waveform monitor and have it set to Luminance.
At the bottom of the waveform, is 0. This is black. At the top is 100 and this is white. What we are going to do is make sure that the darkest areas of our images (the shadows) sit on or near 0, and that the brightest parts of our image (the highlights) are on or near 100 and the rest of the image is nicely in between. Now is a good time to note that going over or below these values will send your image out of Broadcast Safe areas, which will cause you problems later down the pipeline, so its good to get in the practice of getting your image between 0-100. I’ll do another one of these on that later though..
So looking at this image (Im using an image courtesy of www.redrelay.com I believe - a very good resource for RED footage), you can see by looking at it that it looks somewhat flat. You can double check this now by looking at the waveform monitor.
As you see, the dark areas of the image are sitting up and around 11, the midtones are sub 50 and the highlights are ranging from 80 upward to 100. Starting with the shadow control start lowering them until the very bottom of the image starts touching 0. Be careful not to crush them, otherwise you’ll begin to lose detail you might need. If your going for a crushed black look, you can do this later, but for now we’re concentrating on balancing the image.
Shadow Adjustment
So now you’ll see that your image has got a whole lot darker, dont worry, we’ll fix this. When adjusting each tonal range, they also effect the other tonal ranges, so you need to work them against each other, which is why control surfaces are a better way to do such corrections, as you can adjust all 3 at once, rather than one at a time and having to keep going back and forth. Ayway, now your blacks are sorted, next we’ll pull the highlights up toward 100. Keeping an eye between the waveform and the monitor, raise your highlights til the brightest areas are touching 100.
Highlight Adjustment
A little better, but not there yet. Have a look back at your shadows, they will have raised slightly, so you need to go back and lower back to where they were. So now we have our shadows and highlights sorted, the image still looks a bit darker, so turn your attention to the midtones. For the purpose of this example, we’re gonna be raising the midtones. So using your midtones control, raise the mids until they sit roughly between 30 and 70.
Midtone Adjustment
Almost there. Again, your shadows and highlights will have been adjusted follwoing that correction, so go back and fix those until your image looks good to you. I personally like to keep images rich, so never go to high with midtone adjustments, but its a personal taste thing.
Final Image
So now if you go back and forth between the orginal image and the corrected image, you’ll see we have nice deep shadows, rich midtones and bright whites.. Checking this with the waveform monitor you can see just how much we stretched out the image to give it some life.
And thats pretty much the first thing i do when getting an image. First eyeball it, then check what your seeing against the waveform and start correcting. Within a short amount of time this process will take you little time at all, and even quicker if you work off a control surface.
Thanks for reading. Any questions please ask.
Si Cox
http://www.editcrunch.co.uk
