Prior to version 10.4, the color correction tools within Final Cut Pro X were very basic. You could get a lot of work done with the color board, but it just didn’t offer tools competitive with other NLEs – not to mention color plug-ins or a dedicated grading app like DaVinci Resolve. With the release of 10.4, Apple upped the game by adding color wheels and a very nice curves implementation. However, for those of us who have been doing color correction for some time, it quickly became apparent that something wasn’t quite right in the math or color science behind these new FCPX color wheels. I described those anomalies in this January post.
To summarize that post, the color wheels tool seems to have been designed according to the lift/gamma/gain (LGG) correction model. The standard behavior for LGG is evident with a black-to-white gradient image. On a waveform display, this appears as a diagonal line from 0 to 100. If you adjust the highlight control (gain), the line appears to be pinned at the bottom with the higher end pivoting up or down as you shift the slider. Likewise, the shadow control (lift) leaves the line pinned at the top with the bottom half pivoting. The midrange control (gamma) bends the middle section of the line inward or outward, with no affect on the two ends, which stay pinned at 0 and 100, respectively. In addition to luminance value, when you shift the hue offset to an extreme edge – like moving the midrange puck completely to yellow – you should still see some remaining black and white at the two ends of the gradient.
That’s how LGG is supposed to work. In FCPX version 10.4, each color wheel control also altered the levels of everything else. When you adjusted midrange, it also elevated the shadow and highlight ranges. In the hue offset example, shifting the midrange control to full-on yellow tinted the entire image to yellow, leaving no hint of black or white. As a result, the color wheels correction tool was unpredictable and difficult to use, unless you were doing only very minor adjustments. You ended up chasing your tail, because when one correction was made, you’d have to go back and re-adjust one of the other wheels to compensate for the unwanted changes made by the first adjustment.
With the release of FCPX 10.4.1 this April, Apple engineers have changed the way the color wheels tool behaves. Corrections now correspond to the behavior that everyone accepts as standard LGG functionality. In other words, the controls mostly only affect their part of the image without also adjusting all other levels. This means that the shadows (lift) control adjusts the bottom, highlights (gain) will adjust the top end, and midrange (gamma) will lighten or darken the middle portion of the image. Likewise, hue offsets don’t completely contaminate the entire image.
One important thing to note is that existing FCPX Libraries created or promoted under 10.4 will now be promoted again when opened in 10.4.1. In order that your color wheel corrections don’t change to something unexpected when promoted, Projects in these Libraries will behave according to the previous FCPX 10.4 color model. This means that the look of clips where color wheels were used – and their color wheel values – haven’t changed. More importantly, the behavior of the wheels when inside those Libraries will also be according to the “old” way, should you make any further corrections. The new color wheels behavior will only begin within new Libraries created under 10.4.1.
These images clarify how the 10.4.1 adjustments now work (click to see enlarged and expanded views).
©2018 Oliver Peters