|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
BOOKS AND ARTICLES Film and video shooting: how to achieve accurate color reproduction
No lens can react as quickly to changes in light and perceive different shades as accurately as the human eye can. Even walking from a bright street into a small room with burning candles, we clearly distinguish all colors, as our brain constantly balances different light sources. Manufacturers have already spent millions of dollars trying to replicate this process and put such automatic white balance control into camera controls. But, even using the most modern camera, the operator is forced to adjust it in manual mode for the correct perception of colors for each new light source. To do this, he points the camera at a white sheet of paper and waits for it to recalculate the all-important balance of red, green, and blue at a ratio of 1:1:1 to produce pure neutral white when reproduced. (Or the shade that the director of photography needs, for each shade of white, a different sample is used.) Having placed a sample with the required shade of white in front of the camera, the operator begins to select the filters to be installed on the camera. The choice of filters depends on which lamps are used for lighting (tungsten filament, daylight, etc.). The camera electronics adjust the output signals of the red, green and blue CCD chips so that the sample is reproduced without any color distortion. The sample is then removed and the survey begins. It is assumed that after such a setting, the colors will be transmitted correctly. But in the process of shooting, the lighting can change - the sun will go down, clouds will come in or pass, at the same time incandescent and daylight lamps will be turned on. Therefore, the operator has to check the white balance quite often. How to achieve the correct color balance for specific lighting conditions? To understand this, let's recall a phrase from a school physics course that characterizes the visible part of the spectrum - "Every Hunter Wants to Know Where the Pheasant Sits." Red, orange, yellow, green, cyan, indigo and violet are the primary colors of the spectrum. To characterize the color of light radiation, the Kelvin scale is used, and each light source (lighting lamps) is manufactured with a strictly specified color temperature. Depending on the color temperature of the light source, the camera will perceive the color of the subject being shot differently. Most often when shooting films or videos, tungsten filament lighting fixtures with a color temperature of 3200 K (Mole Richardson, Arriflex, Klieg and Lowel) and ordinary household lamps - 2800 K are used. The color temperature of sunlight depends significantly on the height of the sun above the horizon, the season, the amount of clouds in the sky, the presence of haze or fog, and many other changing factors. On a clear afternoon in the Caribbean, it exceeds 12 K, and on a typical day in Chicago, it is 000-5600 K. Below are the color temperatures for various visible light sources.
Red corresponds to the lowest temperatures in the spectrum, while blue corresponds to the highest. Thanks to the white balance function, the camera filters out and "cuts" the excess red and blue colors in the scene, thereby bringing the background to the color that we would like to see. This is all true and understandable if only one type of light source is used on the set (for example, in a studio where only halogen lamps or tungsten filament lamps with a color temperature of 3200 K are used as lighting fixtures). But what if you decide to shoot a scene with mixed lighting, metal halide lights or natural sunlight? How to get the correct white balance in this case? Usually video engineers try to balance all light sources so that they have the same or close color temperature. For this, helium filters are used for color correction. For example, to bring the temperature of tungsten filament lamps closer to sunlight, a blue gel filter is placed on them. And in order to bring the sunlight through the windows into line with the halogen or tungsten filament lamps installed indoors, orange gel filters are installed on the windows. This is how the rules are recommended, but their observance does not always help to solve the tasks that the director sets. Over the course of many years of work, I followed the principle: "First you need to perfectly master all the rules, and then you can easily step over them!" Look around - the world around us is far from always balanced in color, so don't strive for it on the screen! In most of my work, I enjoy mixing and matching different light sources to suit each other. The easiest way to do this is when filming an interview. I have always tried to enliven the face of the interlocutor, placing it in such a way that sunlight, mixed with the light of a tungsten filament lamp, falls on it from the front, and the space around the person is left blue. Very often, I used tungsten filament lamps as the main (directional) light, and metal halide lamps for illumination. As a result of such lighting, the skin color of the subject acquired a warm hue, and a light bluish haze was visible above the hair. If the lamps are swapped, then a clear halo of a very soft warm shade will appear above the head of your interlocutor. Never forget to pay special attention to the character's hair color and skin tone. Experiment with different lighting sources in front of the subject and behind it. Install helium filters and adjust the white balance for each occasion. The effect of changing the lighting can be amazing. Try, for example, shooting on a bus at night, so that tungsten filament lamps mounted on street poles and flashing car headlights periodically illuminate parts of the interior with a contrasting light. And then shoot the same scene again, just set the white balance to the interior of the bus and see what happens to the shop windows. I happened to be on set where the main light source was a candle flame, and the preset white balance ruined the whole scene. After pressing the white balance button, the warm red-orange light fluttering on the wick turned into a dull orange-white reflection, which could hardly excite passionate hugs or hot kisses. To enhance the light effect in scenes with a burning candle, you can use orange or pale yellow helium filters mounted on lamps with tungsten filaments, or reduce the brightness of the glow using a rheostat-dimmer. In some cases, it is very important to achieve accurate color reproduction. So, for example, before shooting scenes for industrial and medical companies, it is often stipulated that colors will not be distorted in the material presented. If the liquid that is poured into a beaker in a chemical laboratory should be light blue, and not violet-blue, then this is important, and we must try to ensure that when played back on video, it is exactly that, and not another color. This is exactly the case when color temperatures should be measured. And although color temperature meters are quite expensive, they are indispensable when working with numerous light sources. Do not forget that white balance is not only a theory, but also a tool for an artist, and a good scientific work is not always the same as a good work of art. Let me tell you the following story as an example. During my youth I worked with a very talented, energetic and persistent lighting director. I was filming a nighttime scene in a parking lot, and I used metal halide lamps as the main light source. To reduce glare in shop windows, helium filters were put on metal-halogen lamps to cut out the green color. But the lighting designer stopped shooting for two hours in order to put special blue gel filters on the headlights of all cars that have tungsten filament lamps. Without this, the headlights would not be white! This delay cost several thousand dollars! Later, with more experience, I came to the conclusion that if the headlights are slightly orange, then this gives the scene an extra dimension. When You Can't Set White Balance Usually a situation in which it is impossible to set the white balance correctly and which annoys me insanely occurs when, in the course of work, it is necessary to remove the TV screen. It's very rare for professional video shooters to realize that most televisions are balanced for color temperatures that are comparable to sunlight (around 5600K)! If, according to the scenario, the actor is placed in front of the TV in the frame and the main light is directed at him from halogen lamps or illuminators with a tungsten filament, and the video camera is balanced for the color temperature of the lamps, then the TV screen will be covered with a bluish haze. pay attention at least to the monitors with which directors of news programs like to fill the back - the image on them is distinguished by a slightly bluish tint. Even filmmakers who make feature films for which huge sums of money are made often make this mistake. True, there are times when the director of photography quite consciously seeks to give the screens located in the background a blue tint, but much more often they simply have no idea about the value of their color temperature. There are some very simple solutions to fix this problem. Use the main light of metal halide lamps with a color temperature of 5600 K to illuminate the person in the foreground, or install blue helium filters on the main light sources with lamps having tungsten filaments. Try to find TVs that can lower the color temperature of the screen to 3200 K. In any case, try to reduce the influence of the TV as much as possible when setting the balance by adjusting the color reproduction, this will allow you to achieve the correct reproduction of color shades in the entire scene. Experiment and try to balance first with the TV influence as low as possible, and then with a tungsten filament lamp with a helium blue filter or a metal halide lamp as dimmed as possible. White balance is sometimes used for psychological impact on the viewer, for example, to convey a different mood or state of mind. So, in the film Traffic, director Steven Soderbergh plays with the audience, painting each location in different shades. Stages set in Washington DC are given a cool blue color while scenes in San Diego are given warm, rich tones. CCDs have made modern cameras cheaper, smaller and more reliable. But according to many video experts, they produce colder, rougher, and far less compelling images. Therefore, diffusion and softening filters placed before and after the lens are widely used to soften the image, as well as special "softening" lighting (diffused light) and amber and light yellow helium filters for the main (directional) lighting. Often, directors of photography adjust the white balance before placing filters in front of the lens or lighting fixtures. And only after that, softening agents are added to achieve the intended effect. Another way to "trick" the camera is to set the white balance with the helium filter in place. If you place a blue helium filter in front of the lens, the camera will register the excess blue in the scene and correct the image by adding more warm tones. Helium filters are available in various densities, so you determine the degree of added warm tones yourself. If you want the scene to take on a colder look, you should place an amber or light yellow helium filter in front of the lens while calculating the white balance. Inactive Tools The leading manufacturers of color correction materials (gels and filters) are Rosco and Lee Filters. But recently a new product has hit the market called Warm Cards, a set of colored cards that allow operators to set the white balance so that the colors are much warmer and more attractive. The use of Warm Cards, which come in three shades, guarantees a permanent warming effect and eliminates gels and filters that have to be unscrewed and then screwed onto the lens whenever the camera needs to be set to a different white balance. In conclusion, I want to note that, ultimately, how you managed to convey color shades will be determined by you and those who give money for production. After all, even for the blue sky and green grass, each operator will offer their own shades. Author: Bill Miller
▪ Lighting as a component of video filming ▪ Video editing. Basics for beginners ▪ Cutting out unnecessary fragments of an AVI file in VirtualDub
The existence of an entropy rule for quantum entanglement has been proven
09.05.2024 Mini air conditioner Sony Reon Pocket 5
09.05.2024 Energy from space for Starship
08.05.2024
▪ Linksys EA8500 Wireless Routers ▪ Mobile phones have been proven to be safe for health ▪ Super glue will close wounds in the stomach and stop the leakage of acids in the plant
▪ section of the site Children's scientific laboratory. Article selection ▪ article Fet Afanasy Afanasyevich. Famous aphorisms ▪ article What role did moira play in the life of gods and people? Detailed answer ▪ Article cerebrovascular accident. Health care ▪ article A simple model of folding flowers. Focus Secret
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
We recommend interesting articles Section 
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page