Range check is an indicator in Apple Final Cut Pro X that allows you to quickly see whether your highlights are too bright.
Why should you care? Because highlights that are too hot lose their detail and turn into a flat white mush. Highlights that are too bright are called “crushed,” because they are crushed against the upper limit of Rec. 709 video.
NOTE: Rec. 709 is a color space that defines the lower limit for black or shadow levels as well as an upper limit for highlights or whites. In Rec. 709, shadows can’t go below 0% and highlights can’t go above 100% when measured on the Waveform Monitor.
Before we go on, I should mention that this will NOT fix problems where you over-exposed an image. However, it will flag problems where your image may need additional color correction.
Here’s an example. The still frame on the left has crushed highlights, while the same frame on the right retains all the highlight detail. The only difference is that the highlights of the image on the left are WAAAY too bright.
Here are the same two examples, except this time, I’ve included the waveform monitor. Notice in the bottom image, where the details are retained, there’s a nice gentle variation in the highlights, while the top image, where the highlights are mush, is crushed near the top of the waveform monitor; that sharp flat line is the indicator of crushed highlights.
NOTE: As you can see from the top left corner in each image, this is a Rec. 709 (HD) project.
Now, truthfully, many times we don’t care about detail in the highlights. For example, a glowing street light in the distance, or speculars from a diamond ring. But, other times we care about the highlights a lot, such as the fine lace detail in a wedding dress, or the sheen and polish of a fine piece of furniture.
Final Cut Pro X has an indicator, called “Range Check” that instantly flags highlights that are too high; we also call these excessive highlights “blown out,” or “too hot.” They all mean the same thing: the levels are so high that highlight image detail is being lost.
NOTE: Just as with audio levels that are too loud, the actual damage to your image isn’t done until you export your project. As long as you correct excessive highlight levels before you export your project, no image detail will be lost.
To enable Range Check, go to the View menu in the top right corner of the Viewer. Down near the bottom are four choices:
Most of the time, for projects that are shot with a camera, we only need to worry about luma levels. Excessive chroma saturation levels most often occur when we are creating motion graphic images or videos on the computer.
For this example, we’ll enable Luma.
When an image is properly exposed and color graded, there’s no change to the display in the Viewer.
BUT! As soon as highlights exceed 100%, a marching “zebra” pattern appears in the Viewer showing where your highlights are too hot.
You fix this using either the Color Board or Color Wheels to lower highlight levels until the zebra pattern disappears.
THIS WORKS FOR HDR MEDIA TOO
While Range Check does not work for Rec. 2020 PQ projects, because a PQ project has no “maximum” white level, this same indicator DOES work for Rec. 2020 HLG projects.
Here’s the same footage (it was shot in Panasonic vLog for an HDR project). The top image shows levels that are not blown-out. The bottom image show the same image with excessive highlights. The range check shows which parts of the image are too bright.
As I mentioned at the beginning, sometimes, we may not care about blown-out highlights. But any time where the essential elements of an image are in the highlights, it’s important to make sure that those levels are safe.
Range check is a fast and easy way to make sure that all the detail in your image is preserved during export. Even better, we can use it for almost every project – SD, HD and HDR.
Here’s a video tutorial that shows Range Check in action.
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