3 minute read
The main process colorists use to achieve visual continuity is called Primary Color Correction.
Primary color correction involves manipulating the entirety of an image. If you change luma or chroma values with a primary color correction tool, every pixel will receive those adjustments. This is why primary correction tools are so useful for shot matching, because they can apply similar changes to different images in roughly the same way.
Typically, the first step of primary correction is to set the luma (brightness) to a desired level. You do this by adjusting the three tonal ranges until you achieve the appropriate contrast or exposure.
The second step is to adjust an image’s chroma (color). This is your opportunity to fix color balance issues, like an incorrect white balance or an add color cast.
After the color channels are balance as intended, you can adjust the saturation of the various hues according to the baseline look you plan to give the shot.
These are the three general steps of shot matching. Though shot matching is not always achieved using just primary color correction processes, generally speaking they are all you need to establish a baseline of color.
That makes primary color correction a particularly technical process. Colorists are not so much making artistic decisions as they are measuring and adjusting specific aspects of an image, at this stage.
Scopes are vital to every phase of color work, but they are particularly useful here. From the start of you color work, you will know what the intended destination of the project is, and can thus make make primary adjustments based on the relevant standard. For example, if your project is headed for broadcast, then you know to set your luma and chroma levels within the legal limits of Rec. 709.
Shot matching is not just a piecemeal process of adjusting every shot in your timeline sequentially. Rather, there is a recommended method that will save you time and effort.
The first thing to do is to pick a Hero Shot. This is a shot that best represents a scene’s color and exposure. Often times this is a wide shot that encompasses many of the details captured in the rest of the scene, such as faces or environments.
Not only is it important that the hero shot be representative of the rest of the scene, but it also must be technically sound. If a shot is massively over exposed or was recorded with a strong color cast (compared to the other shots), then it’s not a good candidate for building a baseline of color. That doesn’t mean it needs to be the best shot, but it can’t be a bad one. In general, choose a hero shot that is as similar to as many other shots in your scene as possible.
This is where your primary color correction begins. As laid out above, you should adjust your luma levels for the tonal ranges, make sure the color balance is neutral, and set the saturation so that skin tones and recognizable colors (like foliage) look normal.
Once you have done this for the hero shot, you can start matching the other shots in the scene to the hero using a comparison window (a special view within your software that will put two images and their scopes next to one another). After all the shots in a scene have been matched to the hero, then the process begins again with the next scene.
This is how you build a baseline of color across your whole sequence. One very useful benefit of establishing the shared baseline is that you can adjust all the shots together, rather than having to do them one at a time. For example, if you match 30 shots to a hero, but later decide you want a different look as your baseline, you can just apply the same global changes to all the shots using an adjustment layer, node, nested sequence, or whichever mechanism your NLE/color software utilizes.
Primary color correction tools are vital to the color matching process, but are also used to build creative looks after the shots have been matched and grouped.
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