Color Correction in Final Cut Pro

Color Correction

Color Correction is one of the last steps in preparing a video for output, and it is also one of the things that tends to differentiate professional videos from home movies. By color correcting your clips you can correct for improper white balance and exposure (to a certain extent), make your shots visually more consistent from clip to clip, or even change the mood or look of a video by shifting the overall colors to make it warmer or cooler. Final Cut has several color correction filters available; today we'll take a look at the basics of using the 3-way color corrector, which is a versatile filter for overall color correction that previews in real time on most systems.

The 3-Way Color Corrector

The 3-way color corrector is applied just like any other filter - either drag it from the effects browser or choose it from the menu bar under Effects>Video Filters>Color Correction>Color Corrector 3-way. However, once you've applied it to a clip you change its settings a little differently than most filters. Double-click the clip you've applied the filter to so that it opens in the Viewer window. At the top of the window you will see a new tab next to the standard audio, filter and motion tabs called "Color Corrector 3-way". Click on this tab (#1 below) and you will be presented with the Color Corrector visual interface:

This is the primary visual interface for changing the color corrector settings. There's a lot of controls, some of which are hidden here, but I'll be focusing on the one's you'll use most commonly.

2. Auto Level buttons: These buttons adjust the white and black points automatically to give you the widest, most evenly distributed range of values in your shot - this works a lot like using the auto levels in photoshop. The first button adjust the darkest pixels in your image to full black, the third button sets the brightest pixels to 100% white, and the middle button does both simultaneously. Using these buttons can give you a good start at adjusting the contrast in your image, but you will usually need to make some manual adjustments after using them.
3. Blacks, Mids and Whites level sliders: These let you manually adjust the black, white and mid levels. Using the auto buttons (described above) will adjust the black and white point sliders automatically; to further change the values manually you can use these sliders. The mid slider is especially useful because it will let you adjust the overall brightness of your image without pushing the blacks or whites too far. The other two are good for increasing or decreasing the contrast of the image.
4. Blacks, Mids and Whites eyedropper tools: This is where we get started with changing the actual colors of the image. The eyedroppers let you pick a spot on your image that should be pure black, white, or a perfect 50% grey, and when you click on it the color controls will adjust to remove any tint on the pixel you selected. The whites dropper is the most frequently used, and it can be helpful to fix bad white balance in a shot. You want to select something that is white - not a bright highlight, but something like a shirt or paper that should be pure white. The mid range selector isn't used as frequently, but if you plan for it when you shoot it can be very helpful. If you hold up a photographic grey card, or better yet a card with areas of white, 50% grey and black at the very beginning of each shot, you can use that card to sample each area and get a good start to perfectly corrected video.
If you are shooting with multiple cameras, especially if they are different models or brands, it is a really good idea to use a reference card with whites, blacks, and grays on it so that you can match the look of all your cameras. Just have all cameras shoot the card under the same lighting (preferably at the same time) with your white balance and exposure controls locked to a single setting. Then you can adjust each camera's footage by using the eyedroppers to sample areas on the cards and get them to look very similar as far as color is concerned.
5. Hue controls: These controls work like a standard color wheel to let you shift the hue of the Blacks, Mids and Whites. You drag the grey dot in the middle to shift the color in the direction you want. Normally when you drag the grey dot moves very slowly - this is because small changes can make a big difference, so you usually don't want to drag too fast. Holding the Apple key down as you drag will allow you to drag much faster.
The direction you drag in determines the color; the distance from the center determines the intensity of the shift. By adjusting these controls manually you can remove color casts, make the video warmer or darker, create a "day for night" look or even tint the video dramatically. For instance, if bright areas in your video look too yellow, drag the Whites or Mids control away from yellow - towards blue. You probably won't need to drag it very much before the yellow hue is eliminated.
6. Color Reset button: Clicking on the small white dot next to each color wheel will reset it back to the center - this only affects that wheel it's next to, and not the level controls for that range.
7. Saturation level slider: This lets you adjust the overall saturation of the video - you can go from black and white (all the way to the left) to extremely over-saturated (all the way to the right). After you've adjusted the level and color controls this can be useful to restore lost color or tone down over-saturated video.
8. Copy from/to buttons: These buttons let you copy color correction settings from or too another clip on the timeline. The middle control (with a hand on it) lets you drag and drop the color corrector with the current settings to another clip on the timeline. The arrow to the right will copy the settings to the next clip on the timeline, while the longer arrow will copy to the second clip down the timeline. The arrows to the left of the hand icon copy from either the previous clip or two clips previous to the current one.
These controls are primarily used in situations where you may be cutting between two cameras, or cutting between one camera shot and other footage. Since most of the shots from the same camera will need the same or very similar correction, once you've corrected the first clip you can just copy the settings down the line. The two clips forward button lets you leapfrog over the cutaways or the second camera's footage to copy to the next clip from the same camera.

These are the basic controls you'll use most often with the color corrector. We'll talk about how to go about using them all together in a minute, but first I want to talk about how you can compare your changes to other clips or the original clip.

The Frame Viewer

The frame viewer is available from the menu bar under Tools>Frame Viewer. This will open up in the Tool Bench window (the same window that holds the quickview window I discussed in the Filters notes). The frame viewer lets you compare a split screen view between frames from two different sources.

1. Source 1: From here you can choose which clip on the timeline to view on the left half of the screen, either the current clip or one somewhere before or after it. For color correction work I usually set this to "Current Frame".
2. Source 2: From here you can choose which clip on the timeline to view on the right side of the screen, either the current clip or one somewhere before or after it. For color correction work I usually set this to "Current Frame w/o Filters" (without filters).
3. Split screen controls: These let you change how the screen is split - V-Split splits the screen vertically, H-Split splits it horizontally, and Swap changes which side shows which source.
4. View screen: Here you can see the current frame split between the two different sources.
5. Split adjustment handles: By dragging these handles around you can manually change how the screen is split.

With the screen split as described above you can see how the changes you've made compare to the original video. An alternative configuration is to set the second source to the next shot on the timeline so you can compare them for consistency as the clips move from one to the next.

Putting it all together

The basic color correction process usually goes like this:

Select the first clip to correct and apply the 3-way filter to it.
Open the clip in the viewer, switch to the 3-way tab, and configure your Frame Viewer window to show the current frame with and without the color correction.
Click the auto contrast button to maximize the dynamic range of your clip.
Adjust the Mid Levels slider to set the overall brightness level of your clip.
Adjust the black and white level sliders to achieve the desired overall contrast.
Use the Whites eyedropper to sample a white spot in your image and correct the overall white balance.
Do the same with the Blacks eyedropper and Mids if you used a grey card in the shot.
Manually adjust the Whites, Mids and Blacks color wheels to correct any remaining color problems or give your video a warmer or cooler overall cast.
Adjust the saturation slider to increase or decrease the overall saturation of the clip
Once the video looks the way you want it to, copy the current settings to all clips from the same shot or scene.
Tweak each clip's individual settings to compensate for any differences from the original shot.

One thing to watch out for is pushing the brightness of a clip too far and ending up with white levels that exceed broadcast-safe levels. To monitor this, from the overlay menu on the canvas select "show excess luma" and make sure your white areas never get red zebra stripes on them as you adjust things.

You can also apply the Broadcast Safe filter (Effects>Filters>Color Correction>Broadcast Safe) after the color correction filter to ensure that everything falls within legal values - for most purposes the default settings will do.

Color correction is a big subject and there are many people who make a career of doing nothing but color correction for film and television projects. Final Cut's built-in tools are fairly powerful and with a little bit of practice will give you a lot of control over the look and consistency of your videos. What I've covered here is only the beginning but should get you started with enough to practice and become familiar with the way color correction works.