Color Correction in Digital Cinema

Introduction: It is usually believed that color correction is the enigmatic process of coping with difficult controls and incomprehensible scopes. It is true that color correction required expensive hardware until recently and this barrier to access made people less familiar with color correction. But now, with the advent of digital cinema and software applications such as Da Vinci, Premiere and Final Cut, these problems are eradicated.

Color correction is related to three areas:

1. Grading: This operation focuses on adjusting the tonality and color. There are two steps to grading;

A: Primary color correction or grading, which deals with changing the tonality (brightness and contrast). B: Secondary color correction that changes the color of a part of an image (the color of an object or clothing).

2. Adaptation: Color correction can be used to match tonality and color in several clips. For example, clips that have been filmed at different times of the day, different cameras, and different settings of cameras.

3. Improvement: Using color correction techniques, it is possible to improve the cinematic image and create a new look and build a special feeling and an element from it to give the image a special quality like the movie.

The following is a description of the general characteristics of color, then the category of color correction in digital cinema will be discussed.

Color recognition:

Isaac Newton invented the color cycle in 1666, stating that light makes us understand color. The color cycle is a circular pattern for recognizing colors in an organized and orderly manner. Since then, many color models have emerged and there has been a great deal of discussion about color theories. But our focus is only on one color cycle that clearly shows colors.

The color cycle is an organized tool that helps us create basic layers for color to be easier to understand. As a chart, this cycle helps you to identify the types of colors well and also becomes a reference for your decisions about the color range of your work.

The image below shows three basic color categories:

Primary or main: red, yellow and blue

Second or secondary: green, purple and orange

Third: which is obtained from the binary combination of each of the primary and secondary colors.

Main color is a color that cannot be obtained by combining other colors. They are basically sources for other colors.

The secondary color is a color that is created by combining two primary colors.

Complementary colors are two colors that are opposite each other in the color cycle, such as red and green. Each secondary color is essentially a complement to a primary color.

Color of the third group is made by combining a primary color with a secondary color which is at the opposite point in the color cycle. Other ways to make these colors include combining three primary colors or a combination of two secondary colors.

Colors of the third group are actually a variety of browns and grays.

Color cycle is actually a useful guide for recognizing colors as well as color combinations of any kind.

There is a common mistake that there is only one primary color-red, blue, and yellow - in fact, there are different variations of blue, yellow, and red, all of which are considered primary. People think that when they combine blue and red, they create purple, but that is not always true. Sometimes they can have neutralizing effects on each other. Neutralization of a color means reducing the concentration and heat of that color. Neutralization is done by combining two or three complementary colors, combining all three primary colors, combining white or black with another color, or combining two primary colors that act as a complement. To find out what color is obtained from a combination of two or more colors, we need to create a color combination table as shown below:

Color elements:

Value, saturation, neutralization, temperature, texture, and opacity are the six elements of color.

Value means relative darkness or relative brightness of color. If we look at a color in different degrees of value, it will be easier to understand the value of that color. When an image is black and white, we can easily understand the value of its color, but when it is colored, it becomes impossible. It is very important to know this because it has a direct effect on the ratio of colors in a work.

Saturation is the intensity of a color that can be distinguished from a particular color or the degree of its color. It may be very colorful, hot, and cold and without heat. If you remove the chroma from a color, it means you have neutralized it.

Neutrality means lack of chroma. If a color does not have heat, it is called neutral.

Temperature is the degree to which a color seems warm or cool to touch.

Texture means the appearance of a color on a surface. Colors may have a cohesive texture or they may have less cohesiveness, this difference affects the overall appearance of that color.

Matte, glossy, and bright color depends on the light that passes through the color. The matte color does not allow light to pass through. The glossy color allows a little light to pass through. And bright color passes all the light.

Controlling the balance between these six elements will help you give your image more power, and controlling the power of the elements in the visual world will give you the feeling that you control the world.

Contrast:

Contrast, the sharp difference between two things, two things that are closely related. If you consider a two-dimensional design in any design, whether it is a painting or a photograph or a film, the contrast allows us to see what is observable.

Understanding the ways in which contrast can be created in the elements of image is the starting point. We need to know why viewers are paying attention to it, and how to keep the audience’s attention through contrast.

We need contrast to see an image, but what makes us react, and how does color affect that reaction?

As a kid, we used to love pictures that had a lot of contrast in the center and the edges. Later, as we got older, we realized the meaning of the shapes. This has certainly been an important skill for our predecessors, as they had to remotely distinguish between friend and foe, domesticated and wild animals, and the like.

As human beings, we pay close attention to soft and hard shapes. Sharp objects remind us of something that harms us while round and soft objects remind us of human and nature. As a viewer, our attention is drawn to high-contrast images. The more colorful spots are seen first, so the most important part of the image should have high contrast.

Hierarchy in an image is the prioritization of the elements of the image based on attracting the viewer’s attention. Creating a hierarchy of contrast, color value, dynamism, color temperature, texture, shape, and complementary colors directs the viewer’s attention towards the image.

Color harmony:

The pleasant coordination of the elements is called harmony. In fact, harmony is a soothing and peaceful coherence between the elements. Harmony gives a sense of totality, meaning a relationship between one thing and another so that the components and fragments are not separated. Another reason to create a path that is harmonious is to create a family of colors that fit together properly.

Basic principles of color correction in film:

Primary acquaintance and understanding of a painter’s job will help filmmakers achieve the right shape and image for their work. Awareness of this issue can be helpful since the beginning of processing the idea of each work and serves to better communicate with the cameraman; it plays its role until the last stages after production. Roy Vasich, color editors of films such as True Blood and Coexistence, advises directors to work with color editors who are first and foremost aware of a color editor job, respect their creativity and accept their views, and have some knowledge of the techniques, know exactly what they want, because with powerful software it is possible to form an infinite number of colors, they will go astray if they do not know exactly what they want.

Color correction in digital cinema:

With the advent of computer in the 1980s, the pain of color correction gradually waned. Currently, there are powerful color correction programs, the most important of which is Da Vinci program, which can be used to modify the color of films frame by frame. Improving these changes requires raw format video recording which has been recorded during filming. The best and most complete of these formats is RAW, which provides a wide range of features when editing and modifying colors. For example, in this format, in addition to the option of changing other formats, it also provides the chance to change ISO. In today’s cinema, using this format is very common, despite the very large volume and many problems to protect these large files, as well as the post-production stages of many movies. This is due to the many options that it provides for the filmmaker at the post-production stage

Adobe premiere, final cut, edius and after effect are other applications that can be used to create acceptable color correction using much simpler elements. Among programs with a primary purpose of editing, Premier is a little better for color correction than other editing programs because of the availability and coverage of many tips and subtleties. Premiere has attracted a great number of fans by creating extensive features in the field of color correction. One of the main advantages of Premiere over Da Vinci is that unlike Da Vinci, the program does not require color correction on the original recorded rushes and it is possible to correct the colors after editing and choosing the best needed rush in each scene but in Da Vinci, the rush must first be carefully selected, corrected, and only then the editing can be done. Possible changes to the required rushes in a scene are some of the time-consuming bugs that occur in the Da Vinci program. In general, Da Vinci program is used for professional and cinematic work, which takes a lot of time, but in short films, telefilms, and television documentaries, the premiere program can be used.

The following is a description of the features provided in the Premier program, which is also applicable in Da Vinci program, but the way to access special options is different, but its function is the same.

Premiere Pro is a very complete collection for color enhancement and correction. We start with the scope. The Premiere Pro has four scopes that we deal with to correct the permanent color; The waves monitor, called luma, is used to adjust the contrast and brightness. The scope vector to show color and saturation, the RGB parade which displays red, blue, and green colors as separate channels, and finally the YCbCr parade which converts itself to the form which is usually available for video, namely CR, Cb, Luma. When you go to the clips, the scopes show you what happened at that moment. And as soon as you create effects or changes to the clips, those instant changes are displayed on these scopes.

Color correction effects:

Premiere Pro has approximately 40 video effects for color correction. The reason I did not use the exact number is that there is no definite rule for categorizing these effects in the color correction group.

We will have an overview of these effects in the following parts; We will see that 10 of them are practical, and by getting acquainted with them, it is possible do all the color correction work.

There are color correction effects in a folder called adobe engineer. There are about 17 effects in this folder. In these 17 cases, there are less important items. But it has four very important and practical ones: fast color corrector, RGB color corrector, RGB curves, three-way color corrector.

RGB color corrector:

These are the main effects that affect the tonality of the color and works with Gamma, Pedestal, and Gain.

The type of approach to tonality is different from other effects. Then with RGB you can work with color intensity levels. And finally, there is something called secondary color correction that allows you to separate a specific part of a clip based on color, saturation, and luma.

RGB curves:

Charts with which it is possible to increase or decrease the amount of white, red, green, and blue in the image.

Fast color corrector: This effect works using the color cycle.

This effect allows you to drag the color to another direction or turn the color in a certain direction. In this section, we have a few level controls that adjust the luma.

Three-way color corrector: This effect is different with Gamma, Gain, Pedestal which was in RGB color corrector, it is level control.

Three way color corrector:

It works with three cycles: one for shadows or black, one for gray and one for highlights and whites.

Here are six other functional color correction effects:

Change to color:

This effect removes one color and changes it.

crop:

Crop is usually used to analyze specific areas of a clip. To do this, select the color at a specific point and modify the same point with one of the above four items.

leave color:

It removes one color and paints the rest without saturation. The amount of this saturation is also controllable.

paint bucket:

Although this effect is often not considered a color correction effect, it is excellent in some cases. It changes a color within another color, and sometimes acts better than change to color.

It allows you to adjust the blending mode also. It is good when you put color in it. Adjust. It's great when you put color in it. Blending mode allows you to do that

tint:

This effect is to get the color of Sepia in Premiere Pro.

track matte key:

In fact, this effect is to highlight a part of the film that is black and dark, and the characters are seen dark, by adding a white piece and adding it to the part that is in black, it highlights that part.

Color and light channels:

Our eyes have three color receivers: red, green, and blue.

TVs and monitors display colors in red, green, and blue pixels. But most video data is displayed using two color channels and a Luma channel. Another reason to use this particular method is that in the early days of television, you needed ways to send black and white signals to the same TV. Hence, it was decided to put all the black and white information and all the Luma information. In this way, apart from being a good way to store information, it does not cause a problem for black and white TVs.

Color temperature, hue and saturation:

We use contrasting terms to describe color. We describe a scene aesthetically. For example, we say that in a particular photo, the sunset is warm, and we might describe another scene as cold. But in fact, when we talk about it scientifically, the opposite is true.

A blue star, which is a hot star, averaging 15,000 degrees Kelvin, is called the color temperature. A red star that is much colder than blue is 3,500 degrees kelvin. So although red feels warm, and blue feels cold; At the scientific level, the opposite is true. The midday sky is bright, very hot in terms of color temperature; It is about 6,000 degrees Kelvin, the sunset is colder but warmer aesthetically; It is about 3500 degrees Kelvin. The fluorescent lamp, which is almost green in color, is about 7,000 degrees Kelvin in terms of color temperature. A tungsten lamp that is a little cooler but feels warmer is much cooler; 2500 degrees Kelvin. So what does all this mean? Now how do we analyze the clip that has compound lighting? Consider indoor scenes filmed indoors with tungsten light and direct sunlight streaks. In this space, the lighting is natural, and in general, any scene that has sunlight has a beautiful white, gray or neutral appearance, because it has reached a balance with the sunlight. This is a compound lighting. You need to know how to deal with the highlights created by direct light that harmonizes with the artificial light inside.

When we talk about chroma, we have two elements: Hue and saturation, which are marked with red, green, and blue channels. If the vector scope is turned on, it is observed that these small red, green and blue boxes are identified beside these lines. These created lines are exactly in line with the color cycle. The outer cycle of the color cycle can rotate the hue. By rotating it, the order of three colors can be changed and placed somewhere else, or two or three identical colors can be created together. It is possible to change positions with 120 degree changes on the color cycle. So there are different uses of the color cycle, In relation to the line called the skin color line (120-degree angle of the scope vector), if we want to change the skin color at this stage, we do not need to rotate the color. We can remove the skin color and rotate it a little clockwise (vector scope).

Therefore, considering these concepts including the color temperature and chroma, which is the hue and saturation, analyzing the color of clips when correcting their color can be done quicker.

Equalizing the light and color of views:

Filming a video in the same situation and at different times of the day or in different lighting conditions is not uncommon. Imagine a sunset and a noon, one looks warm and the other looks a little colder. If these views are edited sequentially, a completely clear change in tonality and colorcast will be observed. What needs to be done is to minimize this discrepancy for the viewer. Matching color and tonality and multiple clips require skill. The process involves: first select a main clip and add it to the timeline, then add the view to make changes to the main clip in the timeline, and use the crop effect to create a two-part screen. Then we compare the tonality, adjust the contrast ratio and brightness of the non-original view to match the main view. We measure the colors, we use the RGB Parade tool and the scope vector, we finally adjust the colors, we start with the highlights very simply, they need the most adjustment. The midtones and the shadows are adjusted and finally the saturation is adjusted using a vector scope. We need both science and art to match the color.

1 Comment

  1. تا حالا کسی درباره اصلاح رنگ آموزش نداده مرسی از توضیحات مفیدتون
    لطفا آموزش داوینچی رزولو رو هم قرار بدید که اصلاح رنگ دقیق تری با شلوغی کمتر و دسترسی ابزار بهتری رو برای کاربر فراهم کرده
    با تشکر

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