A Brief Guide to Color Correction in Films
We will first quote one of the cinema theory textbooks: “color correction (colorization, color synchronization) is the adjustment of the R (red), G (green) and B (blue) color components in order to change the overall color and visual style of the image.” And, in spite of the usual incomprehensibility and intricacy of such theoretical works on film topics, this is one of the most reasonable definitions.
Today we will talk about everything that has to do with the color correction of film media, how to do color correction, why the color correction is important, how to color grade, the difference between color correction and color grading, and everything in between.
But before we find out how to correct color in videos, let’s find out what is color grading in video editing.
What does color mean for a video or a movie?
Video color correction (color adjustment, color synchronization) is the adjustment of the R (red), G (green), and B (blue) color components to change the overall color and visual style of the image. Initially, when image processing was performed on film using the so-called wet processes (development, fixation), the color adjustment was carried out by adjusting the light fluxes R, G, and B when printing on film. In this way, the exposure time was corrected when printing negative. This process was called Color timing. It is used when copying a negative to an interpositive and is designed to provide a match in color reproduction from frame to frame and from scene to scene, that is, to achieve an overall color balance. This is not about the color shift but about controlling the proportions of the components R, G, and B in the final version of the image.
The need for color adjustment is explained by the fact that the material shot on a film of different types or under different lighting conditions has a different kind of color reproduction. In addition, the color adjustment allows you to partially correct the defects that occurred during shooting. This can be, for example, an increase in brightness places that are too dark or, conversely, its decrease in places that are too bright. There is at least one more application of color correction - giving the image some special style. In addition to film production, color correction is also used in video production (including television). When converting visual content from film to video, television sensors are used. During the transfer, color synchronization is also performed.
The work of color grading falls on the shoulders of a specialist called a colorist (color grading operator). Professional colorists are required for sophisticated advanced digital processing, for example, with Da Vinci 2k systems. Typically, the process begins by analyzing the color correction in each frame to fix problems, such as unwanted color tones. Then, the colorist can use many methods to set the color of the scene to reflect the director’s artistic preferences (for example, reducing saturation can give the scene a gloomy mood). When it is decided to give shades to the scenes in a film, this can affect not only a few scenes but the entire film, and this, of course, is a routine because the colorist also has to ensure coherence between frames.
A digital image is always presented in some kind of color model (Red Green Blue, Lab, etc.), implying several (three, as a rule) characteristics for each image point (pixel). The characteristics of all image points are called channels. For example, in the RGB model, each pixel is characterized by the brightness value of the red, green, and blue constituent colors. Accordingly, channels of red, green, and blue colors can be highlighted in the image. Functions can be set as independent for each channel, or more complex - for example, Channel Mixer.
What are the color schemes in a video?
Using color to create harmony or tension within a scene or to draw attention to a key visual idea sometimes leads to stunning results. Now we’ll look at the 5 most common color schemes, which will help you better understand how color correction works in the cinema.
If you ever thought about why certain colors or a combination of colors evokes or awakens an emotional response or just creates a nice picture, this explanation of the basics of color theory can collect all the details of the puzzle into a single whole, or it may arouse your interest in further study.
In post-production, the colorist obviously has to work with what is available, so it can be argued that the overall impression and sensation of the image is the responsibility of the production designer. Everything is carefully planned by the art department of the film crew, which consults with the director and cameraman before the cameras turn on. But if so, how many of us have worked with a professional production designer?
Maybe it happened but definitely not in every project. It often happens that we just take an assistant or call a stylist to quickly search for clothes in a location, or select something from what we have available. And that basic information, which is given below, can be extremely useful in these situations.
1. Complementary colors
Here’s the first of types of color correction of video content. 2 colors, placed opposite each other on the color wheel, make up a complementary pair. This is the most common color scheme for 2 colors. Surely everyone is familiar with the colors of blue and orange (teal & orange). This combination of warm and cold colors, often perceived by us as harmonious, creates a contrasting and lively picture. You can change the saturation, but in most cases, complementary colors are well perceived by our eye.
Orange and blue can often be associated with conflict in action, whether external or internal. Often, an internal conflict within a character can be reflected in the colors of his surroundings.
2. Similar colors
Similar colors are located next to each other on the color wheel. They combine well and can create a harmonious color palette as a whole. These are either warmer or colder colors, and they do not have the contrast as in complementary colors.
Similar colors are easy to use in landscape photography and in the exterior, as they are often found in nature. Usually, one dominant color is chosen, the second is optional, the third is for tinting black, white, and gray shades.
Triads are three colors equidistant from each other on a color wheel. One-color dominates, the rest are just shades. They evoke a sense of animation on stage, even if the colors are unsaturated. Triads are one of the less popular color schemes in cinema. Although it is difficult to implement, it gives a rather amazing effect.
4. Split complementary colors
Split-complimentary colors are very similar to complementary colors, but instead of using one color opposite the base color on the color wheel, 2 adjacent colors are used. There is a similar contrast in color but less provocative compared to a complementary pair.
5. Tetradic scheme
Here’s the last way of color correcting a video. The tetradic color scheme consists of 4 colors, which are 2 complementary pairs. As a result, we get a complete palette of colors with many possible variations. As in most of the given gamut of colors, one color, as a rule, dominates.
Let’s now talk about the differences between color grading vs color correction.
Difference between color correction and color grading
Here is the main difference between color correction and color grading.
Video color correction guide
Color correction comes first. The shot footage tends to be too saturated to the human eye and the process of color correction deals with the color balance, the balance of black and white, brightness, contrast, and such.
Film color grading
After color correction comes film color grading; it’s the next step, and it deals with creating an aesthetic that will be suitable for your movie; it will complete the image that you want to create and the emotions that you want to provoke.
How to color grade video: basic rules
A few years ago, color correction was considered an expensive stage in post-production, which only high-budget projects could afford. Today, there are many affordable programs and applications for working with color, but in order to use them wisely and save resources, it is necessary to take into account a number of important details.
The better the footage – the less color correction will be required
How to color correct video? This applies to everyone who works on the production of paintings. Supervisors, producers, cinematographers, directors - everyone involved in making the film should make sure that the frames for further color grading are shot in the right way from the very beginning. For example, to facilitate the work of a colorist, the cameraman can set the LUT preset in the camera settings before shooting. It is important to know your camera and its capabilities thoroughly; then the color correction process will be much easier.
Access to files must be locked
When you do color correction for videos you have to think about security and access to files. This may seem obvious, but do not forget to lock access to the draft editing version of the film before transferring it to color grading. There are many cases when the material is transferred for color correction and then changed, which causes the colorist to do double work. Many color grading programs (such as Resolve) have the “Color Trace” function, which allows you to copy the previously used color scale and apply it to all the changes made to the project. But you need to understand that this function does not always work as it should, and sometimes even adds problems. Therefore, make sure, before carrying material for color correction, that the draft editing version is locked for editing.
How to color grade video? Despite the fact that there are many programs (for example, FCP X and Premiere Pro) that allow you to work with source files in RAW format, some still prefer to use proxy files for editing. A proxy is a smaller version of a RAW file with a lower resolution, which allows you to work with the material much more efficiently. At the final stage, you rearrange the proxy files back to RAW. The problem is that you must know with extreme accuracy how to create a proxy file correctly; otherwise, you will not be able to recompose the materials at the right time. Most importantly, the name of the proxy file and the RAW must be absolutely identical (except for the file extension, which depends on what format you use).
Be careful with files with a modified playback speed
As a rule, projects are transferred from the editing program to the color grading program using a special file (translation file) - XML or AAF format. Initially, they serve to enable the program to correctly decode the location of previously mounted material. Ideally, everything is accurately transmitted, but in fact, it turns out that this does not happen often. One of the main problems is the interpretation by the program of files with distorted time (that is, those files whose speed has been increased or underestimated), due to the fact that the color correction program does not always recognize speed data and the changed file goes into the program at its original speed. This problem can be solved by exporting time-synchronized files individually, separately from the whole project. As an option, you can also separately correct this file at normal speed and add a ready-made file to the installation and change its speed.
We hope this basis will help you in choosing the color scheme of your film, both in working with your stage designer and while working with the post-production crew, depending on your type of activity. Color may be the entire idea behind your movie, its main gimmick, its shtick, the thing that makes it stand out from the rest. But, if not, it still plays a very large role at all stages of filmmaking, as it can not only convey emotions but also point out what is important and turn something boring into a very exciting and vivid image.