I often get asked why color looks differently on a client's monitor. Or why it looks different on TV. Or why, if a client wants to discuss color, they should come into our offices rather than review the video in the comfort of their own. In my previous post on color grading, I gave an overview of what I do and why. This post is more about how; not which dials I use out of the myriad available—this isn't a howto—but how I gauge color, how I see it.
Monitors and Accuracy
Before you can even begin to adjust the color of a video, you have to know what you're looking at is accurate. Recall visiting an electronics store: Did the television section not throw you off, with every TV seemingly having a different color, brightness, vibrance? Even if you bought five of the same television—even if all five came from the same factory and were built on the same day—they would still look different. Add to that, monitors change color as they age; newer monitors are often very blue, but tend toward warmer oranges as they age.
And, FYI, computer monitors display color differently than televisions. The current standard for HDTV is Rec. 709. This varies from the standard for computer monitors, sRGB. Meaning, a video played on your monitor will look different than a video played on your TV. Most computers have software that tries to account for this difference, but the adjustment made isn't perfect.
So which color do you believe? Which is truer? How do you tell? Does it matter?
Knowing that all consumer televisions and computer monitors are different, your argument may be that as long as it's close it doesn't matter. But if your monitor is only "close" to accurate, how would you even know how close? Maybe it's a little too blue, or a little too red, or maybe it's a little bright? The human eye, paired with the visual cortex that drives it, is remarkable. If you only have a single image in front of you and no other light source to judge it by, your eye will auto-correct what you see so that it looks accurate. More-or-less.
So what do you do? Here's the short version: There are plenty of companies that manufacture professional grade video monitors. First you buy one, then you calibrate it. Sony, Marshall, Panasonic, JVC, and Blackmagic Design all make solid monitors at the professional level. When we were shopping around, we chose to go with Flanders Scientific—specifically, the CM171. Where other companies like Sony and JVC produce thousands of products, FSI does one thing: manufacture monitors for filmmakers. They are, arguably, the best or one of the best manufacturers on the market. Even better, FSI monitors come factory-calibrated.
As anyone in a technical job will tell you, you have to trust your instruments. In color grading, those instruments are called scopes. Scopes are a collection of graphs that show the color of an image in different ways.
Scopes are a book in themselves, but here are a few examples: A waveform monitor distributes brightness along the y-axis while keeping the x-axis associated with the x-axis of the image. A vectorscope is a radial graph with six radii representing red, green, blue, cyan, magenta, and yellow, where the further from the center a point is the more saturated (vivid) the color is. A histogram is a line graph that associates the x-axis with brightness (black on the left, white on the right) and the y-axis with the amount of the image at that brightness.
Having fancy tools is great, but the human eye is deceiving. In order to make sure your eyes are adjusting for the monitor and not anything else, the walls of the room need to be neutral and any furniture should be muted in color. Any external light source also has to be calibrated. (Your local hardware store does not carry well-calibrated lights!) And, most color grading software is best utilized with two computer monitors. There's just too much to display on one screen.
Here's a view of our setup. We're in the process of reorganizing our office space (we still haven't finished putting the editing and color bay back together), so forgive the clutter of cords.
See also: Color Grading, Part 1