How do I use the RGB Curves in Lumetri Color?

The RGB Curves in Lumetri Color offer powerful control over your footage’s color and tonal range. By adjusting individual red, green, and blue channels, you can precisely fine-tune contrast, color balance, and create specific looks. Mastering this tool unlocks a new level of creative grading.

Understanding RGB Curves in Lumetri Color

Lumetri Color, a staple in Adobe Premiere Pro and After Effects, provides a comprehensive suite of color correction and grading tools. Among its most potent features are the Curves. While the general Curves panel allows for global adjustments to luminance and color, the RGB Curves section delves deeper, offering channel-specific manipulation.

What are RGB Curves?

At its core, an RGB Curve represents the relationship between the input values (original pixel brightness) and the output values (adjusted pixel brightness) for a specific color channel. The graph displays this relationship, with the horizontal axis representing the input (from black on the left to white on the right) and the vertical axis representing the output (also from black at the bottom to white at the top).

• Input: The original luminance or color value of a pixel.
• Output: The new luminance or color value after adjustment.
• The Curve: A line that maps input values to output values.

When you adjust the curve, you’re essentially telling the software how to remap those input values. For example, pulling down a point on the curve will make that specific input brightness darker in the output.

Why Adjust Individual RGB Channels?

Adjusting the overall RGB curve affects all three color channels simultaneously. This is useful for general contrast adjustments. However, by targeting individual red, green, and blue curves, you gain much finer control.

• Color Correction: You can correct color casts by adjusting the balance between the primary colors. For instance, if your footage has a green tint, you might slightly lower the green curve in the mid-tones.
• Creative Grading: This is where the real artistry comes in. You can create unique looks by selectively boosting or cutting specific colors at different brightness levels. Think about adding warmth by lifting the red curve in the highlights or creating a cool, moody atmosphere by lowering the blue curve in the shadows.
• Contrast Enhancement: While the master curve handles overall contrast, individual RGB curves can add nuanced contrast within specific color ranges.

How to Use RGB Curves in Lumetri Color

Accessing and manipulating the RGB Curves is straightforward within the Lumetri Color panel.

Locating the RGB Curves

1. Open your project in Premiere Pro or After Effects.
2. Select the clip you wish to color grade.
3. Open the Lumetri Color panel (Window > Lumetri Color).
4. Navigate to the Curves section.
5. You will see a dropdown menu. By default, it’s likely set to "Hue Saturation". Click this and select "RGB Curves".

You’ll now see three distinct curves: one for Red, one for Green, and one for Blue. You can select which curve to edit using the corresponding color swatch or by clicking directly on the curve.

Basic Curve Adjustments

The fundamental way to adjust a curve is by adding control points and dragging them.

• Adding Points: Click anywhere on a curve to add a control point. You can add multiple points to create more complex shapes.
• Dragging Points: Click and drag an existing point up or down to change the output value for that specific input value.
  • Dragging a point up increases the brightness/intensity of that color channel at that level.
  • Dragging a point down decreases the brightness/intensity of that color channel at that level.
• Removing Points: To remove a point, drag it off the graph area or right-click and select "Delete Point".

Common RGB Curve Techniques

Here are a few practical ways to use RGB curves for both correction and creative grading:

1. Correcting Color Casts

If your footage looks too blue, you might want to add warmth.

• Select the Blue curve.
• Add a point in the mid-tones (around the middle of the graph).
• Drag this point down slightly. This reduces the blue in the mid-tones, making the image appear warmer.

If your footage has a green tint:

• Select the Green curve.
• Add a point in the mid-tones.
• Drag this point down slightly. This reduces the green, balancing the color.

2. Creating a "S" Curve for Contrast

A classic "S" curve is used to increase contrast. While often done on the master luminance curve, you can achieve a similar effect with RGB curves, or enhance it.

• Select the Red curve.
• Add a point near the bottom left (shadows) and drag it down slightly.
• Add a point near the top right (highlights) and drag it up slightly.
• Repeat for the Green and Blue curves, but you can vary the intensity to add color shifts. For example, you might lift the red more in the highlights for a warmer feel.

3. Faded Film Look

To achieve a desaturated, faded look, you often lift the black point and lower the white point.

• Select the Red curve.
• Add a point at the far left (black point, input 0) and drag it up slightly. This lifts the blacks, making them appear gray.
• Add a point at the far right (white point, input 255) and drag it down slightly. This crushes the whites.
• Repeat for Green and Blue, but you can introduce subtle color shifts. For instance, you might lift the red and green slightly more than the blue to give the faded blacks a greenish-blue tint.

4. Specific Color Grading Looks

• Teal and Orange: To achieve this popular cinematic look, you often desaturate blues and greens in the shadows and boost oranges/reds in the highlights.
  • On the Blue curve, pull down the shadows.
  • On the Green curve, pull down the shadows.
  • On the Red curve, lift the highlights.
• Vintage/Sepia: This involves boosting reds and yellows and desaturating blues.
  • On the Red curve, lift the highlights and mid-tones.
  • On the Blue curve, lower the shadows and mid-tones.

Using the Dropper Tools

Lumetri Color’s RGB Curves also include eyedropper tools. These are invaluable for precise color correction.

• Targeted Color Picker: Click this eyedropper. Then, click on a neutral gray or white area in your footage. Lumetri will analyze the color and suggest adjustments to the RGB curves to neutralize that color cast.
• **Black, Gray, White Point Droppers