There are two things that are at the core of doing good color grading for video:
- Ensuring that the image on the screen looks great and is graded to best tell the story; and
- Making sure that the image can be properly reproduced and delivered to a variety of media and screens.
This article will focus on the latter. Understanding the importance of legal and valid gamut and determining the color balance are critical to maintaining proper color reproduction across a variety of media and broadcast methods. Before we examine the concepts of color balance, let’s quickly review the concepts of color space.
The HSL color space
Video is comprised of three color components: red, green and blue (RGB). Various combinations of these colors make up the colors we see. One way to understand the Hue Saturation and Luma (HSL), or RGB color space, is to imagine it as two cones joined at their widest point, as shown in Figure 1).
The waveform monitor
The waveform monitor or rasterizer (scope) is key to providing a legal output of your creative product. Being a brilliant editor and colorist doesn’t mean much if no one will air your product. Even if your product isn’t being broadcast, legal levels affect the proper duplication of your project and the way it will look on a regular TV monitor.
One of the most basic uses of the waveform monitor is determining whether your luma and setup levels are legal. This means that the brightest part of the luma signal does not extend beyond 100 percent and that the darkest part of the picture does not drop below 0 percent.