Levels and Curves and Color Correction Oh My!

A couple of weeks ago I raved about the “gateway to goodies” plugin application FxFactory by Noise Industries. Today I want to quickly give my two cents on one of the plugins you get can via FxFactory – Nattress’ Levels and Curves. (Disclaimer: I was granted an NFR code of this program so that I could perform this review.)

As the name suggests, this plugin is used to adjust the levels and curves of your footage, essential for color grading and correction.What are “levels and curves” you ask? Put simply, curves are adjustments you can make to luma (light/exposure) and color (RGB) levels in your highlights, midtones and shadows. Levels relate to adjustments you can make to whites, blacks and gamma in your footage. These are all elements that when tweaked can give you different color grading looks; or can be used to “fix” footage (e.g. adjust over or under exposures where information isn’t lost, etc.)

I use Final Cut Pro X (FCPX), but the plugin is also available for use in Adobe Premiere Pro, After Effects, Motion and Final Cut 7. You’ll need MacOS X 10.7 or later and FxFactory installed (FxFactory is free). One of the beautiful things I love about FxFactory is that once you purchase a license to a plugin, you have the option to make it available for all host applications.

If you’re an FCPX user, you’re probably already familiar with Final Cut’s new color board. It’s a radical new way of looking at color grading and correction, doing away with the traditional color wheel. If you’re used to the color wheel, I’m sure this was a pain in the arse. If you’re not used to it, you may have found the color board to be very intuitive and easy to use.

In any case, Levels and Curves give you a more traditional way of adjusting contrast, highlights, etc.

Shooting Flat

Nattress’ Levels and Curves are ideal for DSLR filmmakers shooting with a flat picture profile. This is a color profile where contrast, sharpness and saturation are dialed down, giving the footage a “flat” look. The purpose is to preserve details in blacks and highlights, similar to what RAW footage gives you. You should only shoot flat if you plan to do color grading of your footage and want more control and flexibility. If time is of the essence, or if you’re not too comfortable working with flat video footage, it may be best to shoot in a more traditional color profile (e.g. Portrait, Standard, etc.)

There are four plugins that come with Levels and Curves: Curves, Curves Luma, Curves RGB and Levels. Let’s briefly look at each using a clip from the raw footage of my short film “S3P4” (coming soon by the way.) Here’s the untreated footage (shot with a flat profile on a Canon 7D):

Now let’s look at the various plugins. In each example I’m using what’s considered an “S-curve.”  Look at the image below to see why it got that name. S-curves are a popular distribution of high, mids and blacks common to traditional cinematic film. Click on an image to see it larger.

Curves tweak the blacks, mids and whites along the whole color space. When you first apply the plugin, a diagonal line appears on the clip. From here you can adjust the whites, mids and blacks (as well as the “toe” and “knee” values). You can also make these adjustments in the inspector window if you want to dial in an exact value. Notice the difference in contrast and color between this clip and the raw footage.

Curves Luma just affects the luma values, not the color. You might use the plugin if you’re more concerned with just exposure levels, and don’t want to change saturation or the color temperature. You’ll notice that the color temperature of this is closer to that of the original raw footage. The key difference is the contrast.

Curves RGB allow you to tweak the levels in each of the primary colors: red, green or blue. In this particular instance, I selected to adjust the levels to the preset “Cool Highlights, Warm Shadows.”

And here’s the clip without the guides:

Finally, we have the Levels plugin. This plugin is used to manipulate black, gamma and white levels in your image. Gamma is kind of a difficult term to explain. At it’s basics, it’s the setting of the greys in your image. Differences in gamma setting is why one image or video may look one way on a Mac and darker on Windows. Often you can “lighten” an image by changing the gamma. This will tend to preserve more of the details than boosting the whites or highlights.

Scopes Are Your Friend

Whenever doing heavy color correction work, the scopes are your allies. One of the scopes you may find used most often is the Waveform monitor which shows white and black levels on a scale of -20 to 120 (with 100 being pure white). This is called an IRE scale, and these values are particularly important when producing broadcast work. Here’s the gamma-adjusted image above and the corresponding waveform (luma values):

When using any of the Levels and Curves plugins you should work with one of the scopes alongside. You should also consider using the waveform RGB  parade (shows the IRE levels for each of the three primary colors) and the Vectorscope (that circular scope which displays color values and is great for making sure skin tones are correct).

How I Use the Plugins

Since I shoot just about all of my work with a flat profile, I use the Levels and Curves plugins a lot. On pretty much every job I do now. Every now and then in addition to the curves plugin, I’ll also teak the exposure levels in my FCPX color board. I also really like the RGB Curves presets and often add one of those as a starting place. I will frequently add both an RGB curve as well as a luma curve and adjust each accordingly. As of yet, I haven’t been too crazy about the values I get using the “regular” Curves plugin. But it’s all subjective.

Nattress is a well-respected and recognized leader in providing effects and plugins for Mac editing platforms, and this latest edition is well worth adding to your toolbox.