Subtractive color grading refers to the process of altering the color and brightness of footage during post-production by removing certain colors from the image. It is a key technique used in film and video editing to set the overall mood, aesthetic, and visual tone of a scene or entire production.
How subtractive grading works
Subtractive grading gets its name from the subtractive color model used in mixing paints, dyes, inks, and other pigmented materials. Unlike additive color mixing where red, green, and blue light are combined to create a range of hues, subtractive color mixing starts with white light and colors are created by subtracting wavelengths using colored filters or pigments.
In video editing, this same principle is applied digitally to remove or subtract colors and darken the brightness levels of footage. This is achieved using color correction software tools that manipulate the color channels and luminance of each pixel in a shot.
The three main color channels that are adjusted in subtractive grading are:
- Red
- Green
- Blue
By selectively lowering certain color channel levels, the colorist can shift the overall color cast and mood of a shot. For example, desaturating reds and greens will cool off and darken the look. Bringing down blue channel levels will warm up the shot and give it a more inviting, golden tone.
When to use subtractive grading
Here are some of the most common uses of subtractive color grading:
- To create a specific color theme or mood – Subtractive adjustments like draining color or adding contrast can set a ominous, gritty, or nostalgic visual tone.
- To make footage match across scenes – Bringing separate shots or scenes to the same relative brightness and color balance.
- To direct viewer attention – Darkening peripheral areas can focus more attention on key subjects or characters.
- To compensate for imperfect production conditions – Correcting uneven, unflattering, or inconsistent lighting or color.
- To emulate a film look – Desaturation and curved adjustments mimic the characteristic look of motion picture film stocks.
Ultimately, subtractive grading comes down to controlling how colorful or subdued the end result appears and guiding the viewer’s emotional response.
Subtractive grading vs additive grading
It’s important to understand the difference between subtractive and additive color grading:
- Subtractive – Lowers brightness, saturation, or specific color channel levels to alter the original color
- Additive – Introduces new colors not originally present through effects like tint, selective color, or glows
Additive grading builds on the existing shot colors. Subtractive grading takes away from them. Colorists will often use both approaches in combination.
For example, they may start with subtractive methods to get the overall look close and balanced. Then they will selectively use additive techniques like tinting for creative highlights or stylistic flourishes.
Steps for executing subtractive grading
While every colorist will develop their own creative methods, here is a general subtractive grading workflow:
- Balance overall exposure from shot to shot
- Neutralize color cast issues and adjust white balance
- Lower/raise primary color channel levels for desired look
- Adjust individual RGB curves for contrast and rolloff
- Add secondary adjustments via HSL keys if needed
- Finesse the grade with master wheels
- Check skin tones and vital colors don’t look unnatural
Advanced colorists will also leverage other tools like power windows, custom LUTs, and camera RAW formats for more options. But the core subtractive process remains adjusting those essential red, green, and blue channels.
Critical color grading tools
There are many software options for subtractive grading these days, but the most common professional tools include:
| Grading Software | Key Features |
|---|---|
| DaVinci Resolve | Industry standard grading app with advanced color wheels, curves, keys and scopes |
| Adobe SpeedGrade | Direct manipulation grading for Premiere Pro users |
| Apple Color | Legacy application with intuitive grading interface |
| Autodesk Lustre | High-end grading system for feature films |
These applications provide fine control over individual color parameters like lift, gamma, and gain per channel, hue adjustments, and varied curve options. This level of image manipulation is required for professional subtractive grading.
Achieving popular graded looks
Many classic color styles have emerged over the history of cinema. Here are some of the most popular subtractive grading aesthetics used for creative and dramatic impact:
High Contrast Black & White
This striking high-contrast effect accentuates texture and form. It requires adjusting tonal curves to increase midtone contrast and really push the blacks and whites.
Sepia Tone
Reducing saturation towards monochrome and adding an antique yellow/brown tint mimics vintage sepia-toned photographs.
Teal and Orange
Lowering blues and warming shadows to orange offsets the teal highlights. This look dramatically separates skin tones and backgrounds.
Bleach Bypass
A chemical film processing effect replicated digitally by desaturating shadows and heightening contrast. Creates a gritty, distressed appearance.
Crushed Blacks
Pushing black levels down makes shadows purely silhouetted black shapes. Intensifies high-key lighting effects.
Color Wash
Tinting the entire image towards bold singular hues like green, magenta or cyan. Used to evoke moods or reflect environments.
Common subtractive grading mistakes
It’s easy to go overboard and ruin the natural quality of well-shot footage. Here are some frequent subtractive grading pitfalls to avoid:
- Over-desaturating – Draining too much color flattens the image excessively
- Clipping channels – Crushing shadows or blowing out highlights loses detail
- Introducing noise – Underexposing areas or crushing blacks reveals ugly noise
- Skin tones off – Unnatural green, pink, orange, or yellow looking skin
- Color banding – Visible stepping between color gradients from aggressive curves
- Mismatched shots – Inconsistent black levels or color between adjacent shots
The key is to apply subtractive adjustments judiciously and with restraint. Small changes can make a big difference. You can always do more, but it’s hard to undo really drastic grading.
How to learn subtractive grading
Mastering the subtleties of subtractive grading takes patience and practice. Some tips for improving your skills over time:
- Study films and shows with great cinematography to see professional grading in action
- Experiment with different styles when color correcting your own projects
- Read up on color theory like complementary colors and color psychology
- Take online courses focusing specifically on color grading techniques
- Watch video tutorials from experienced colorists to learn their process
- Work as an assistant to a professional colorist and observe their methods firsthand
With the right eye for color and contrast, creative vision, and technical know-how, you can become an expert at subtractive grading. Mastering this essential process will give your films and videos the polished, cinematic look that audiences and clients expect.
Conclusion
Subtractive color grading is foundational to the entire post-production process. Manipulating color channels, contrast, and luminance gives editors immense creative control over the look of footage. From creating intense black and white to warming up tones for a nostalgic effect, subtractive techniques are used to set just the right mood while making shots visually cohesive. While it takes practice to master, understanding color correction concepts and the subtractive process will give you the skills to grade footage just like the pros in Hollywood.
