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OJANS
EVER WONDERED WHAT'S THE DIFFERENCE BETWEEN THE TWO?
Colour Correction vs Colour Grading
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Colour Correction vs Colour GradingBojan Cosic
00:00 / 06:42
One of the reasons we like to watch movies, besides the story, is the beautiful imagery. The art of filmmaking is successful when establishing an impression that makes us forget we are watching a film and rather leaves us feeling like witnesses to the events unfolding. This is achieved with all of the elements of the process, such as cinematography, script continuity, editing, pacing, performance. The imagery itself derives from the art of cinematography. Closely tied to cinematography are both disciplines of color correction and color grading. In that order. To understand these elements and the relationship between them, we must recognize the following.
Images created in the camera are dependent on the light. After all, that's what digital and film images are, captured light. Quantity, quality, temperature (color), and contrast are captured by the camera through a sensor and converted into digital data. As a natural force, light is a bit wild, and for the purposes of filmmaking, it must be tamed. A sequence of images, edited one after the other, making a seamless flow in a certain space and time is how movie magic is created. The viewer needs an uninterrupted experience in order to stay in the story, rather than become distracted by errors, where inconsistency could consciously, or subconsciously jolt the viewer out of the story distracting them from what the movie is communicating. With delicate lighting conditions on the set and even use of different cameras and lenses between shots, sometimes even despite the best skills and efforts of the Cinematographer or Videographer, the consistency in lighting becomes compromised. Threatening continuity and the ease of viewing.
Enter, Color Correction.
Color correction is a corrective technique for balancing footage with the use of hue, saturation, and brightness to a universal look, or one that is consistent with the whole sequence of images. It seeks to achieve a healthy, balanced and vibrant image, as a stand-alone or as a part of a sequence.
Even though reserved for when video editing is complete, it is at times a part of the editing in the early stages to assure that the faulty clip is in repairable condition, therefore allowing for confident use in the edit that will not cause issues by the time color correction ensues. As a procedure, it is far more technical than creative.
Video media is captured in a color space. This is a range and a set of rules that every camera uses to digitalize light images onto a media file. All cameras use a color space, either an industry-standard one or a manufacturer-specific one, making different models and camera manufacturers have quite a distinguished-looking footage. It is why you might see that the black is darker on one camera and lighter on the other, or some elements appear green on one camera, but blue on the other, despite the matching settings.
Rec709 is one such color space hosting this information, most commonly used as it can be displayed on most device screens, projectors, and TVs. While bigger is always better in Color Correction and Grading, as an abundance of information in manipulating images is more forgiving, Rec709 has a relatively small number of colors, which in turn gives it more consistent results on multiple displays making it ideal for delivery.
They differ from each other as some color spaces simply see more colors than others and process them differently. This is an issue. Performance of all cameras used in the project will be consolidated into one color space, whether it is the very same as captured, different, or the project contains multiple, they all need to conform to the color space of the edited project while maintaining a consistent look.
A useful tool in managing these color spaces is Color Space Transform (in the example of Da Vinci Resolve) and LUTs. CST converts color spaces manually, where we input the information of what needs transforming into what. LUTs, short for the Lookup Table, are algorithms that serve as filters that convert one color space to another at a click of a button. This is only one way in which LUTs are useful, but more on that later.
If we spend enough time in a room with yellow light, our brain will start believing it is white. Therefore, we could perceive yellow objects as white. This subjectivity hinders our judgment because the brain can be deceived. For this reason, to perform color correction and color grading we need a variety of tools both for intervention and analysis.
Most software applications are equipped with a few types of scopes that show the true levels of exposure, color balance, and saturation, ensuring that each shot is technically consistent and that the colors are safe for broadcast with greater accuracy than a human eye can observe. They come in different forms of diagrams, meters, scopes that measure to show levels and color objectively.
Interventions in the process of color correction are in aligning and adjusting image parameters such as brightness, hue, and contrast, on parts of, or the image as a whole.
Brightness is certainly the most notable feature of every image. With its adjustment, we seek to keep the subject at the optimum exposure, while the brightest and the darkest parts of the image remain within ranges of the color space used for the project. Any parts of the image that are too bright, or too dark will show on the waveform scope as outside of the boundaries and on the screen as completely white, or completely black, soaking up any and all detail in the image. As, for example, you might see clouds just as a big white blob, or a person's black coat without wrinkles or ripples.
Contrast adjustment attends to the relationship between the bright and the dark. The captured scenes can differ in contrast. In controlled conditions, contrast is the cinematographer's creative decision. In the image above, contrast is too high to an extent that it is pushing the image out of legal range resulting in loss of information. Yet a low contrast image is often not pleasing. The waveform scope will display it as far too inside the boundaries. Within most color spaces, the image is optimal when stretched to the limits of brightest and darkest, yet limited to inner boundaries of the legal broadcast range.
The Hue adjustment seeks to establish a true color, where white would show as truly white, black as truly black, and everything in between accurately represented. The blueish morning, versus bright noon, versus indoor, etc., all have a different color cast. The camera does not have a sophisticated perception as the human brain does, and it is cramming the "infinite" number of colors into a limited color space of the camera.
Our brains are sensitive to skin color, as discoloration could give us an impression the person is ill, or not human altogether. In order to mitigate this, camera operators use the White Balance setting to let the camera know what is the reference point at which it records color. If White Balance is unadjusted/unbalanced, the image could seem overly yellow, blue, green, or magenta, and white objects in the image notably would not be white. It is normal even for the most professional shoots, to have these balances slightly off by the circumstances of unpredictable lighting conditions. We mitigate this with the hue adjustments.
As the color correction phase is completed, we have shots that look like they belong to each together. They are displaying all captured detail and providing us with a completely watchable and enjoyable product. While we have compensated for any misalignment or errors in the footage by applying uniformity, we were not overly creative, only technical. To really "blow it out of the park" with the cinematography, we need to engage in the next phase.
Enter Color Grading.
What is Color Grading and how does it work?
Color Grading seeks to achieve a certain stylized tone and mood, enhancing the intended emotion, complementing cinematography with creative uses of hue, saturation, exposure, and effects.
Color grading uses, to a great degree the very same tools as the process of color correction, but it approaches the footage quite differently. With color-corrected shots in hand, we are free to apply creative alterations to groups of clips, scenes, or even the whole film with the process of Color Grading. In bulk. Individual clips do still need attention, so this exists only in theory, but it sets us off to a much less time-consuming endeavor, as color correction is complete.
LUTs, come into play here once again and are used as filters to change the dynamics of color and luminance of images. Anyone can create LUTs, in order to preserve and share a stylized look that they have created. In Color Grading, unlike in Color Correction, they have a wider use and their variety is unlimited, as they are used for creative purposes.
Although a very useful tool, LUTs ARE NOT a substitute for Color Grading. While they provide a great advantage in moving the grade in the desired direction, they could only be used as a basis to start from. More often than not, Color Grading is done on top of Color Corrected footage, from scratch.
Many parameters and regions of the images are manipulated, subtly, rather than only a few intensely. Effects like a sharpener, blur, and grain are used to affect a whole or a portion of an image. With great care, the process must never be overbearing to an extent that it draws attention to itself. For the viewer, the process of Color Correction should be invisible and all the images are usually attributed to Cinematography. As the final step in the production of imagery in the project, the impression and mood the images will communicate must be arrived at delicately. It is not unusual for the process to be repeated on a project multiple times, as the feeling and mood are honed in and finely tuned.
Color Correction and Color Grading are crucial steps in transforming films and picture projects from raw beauty to vibrant, magnificent worlds. Introduced out of necessity, to compensate for technological issues, they developed into an art form. In addition to the retention of great knowledge, a Colorist still must possess, or develop a sense of style, subtlety and be a great fan of esthetics.
It is a sought out and satisfying endeavor that takes a lot of practice and once set on it, it is hard not to enjoy the journey.
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