Three rules for maximum image color Temperature setting

The best color temperature setting-Why use color temperature is a panacea for color optimization?

The white balance setting is the color temperature setting. The concept of color temperature belongs to the basic knowledge of traditional photography, this section is not prepared to explain the color temperature too much, only to discuss some of the concepts related to digital white balance. Although the principle is the same, but the digital technology to the application of color temperature and control not completely copy the technique of film, set, change the operation of color temperature is very different.

Since Kelvin explained the color temperature in mathematics, the color temperature is quantified, it can be from film manufacturing, light use, filter correction, until the darkroom to restore all the photographic link to grasp the color temperature, and finally achieve the purpose of accurate expression.

In traditional photography, we talked more about the sun-type, light film. The most used color temperature filter is the Ryden 80 and Ryden 85 series, to light and daylight-type film through the color filter conversion temperature. One of the tips is to use the sun-shaped film to shoot the sunset without the filter to make it more red, or use light film to shoot the night sky, without dropping the color temperature Figure 3-55 filter, and make the screen more blue, through the micro-inverted calculation with a variety of filters to control color temperature. But it's not easy to buy and go out with a lot of expensive lenses, so unless you need it, the general photographer will not buy a full set of color temperature filters to control the color temperature. In other words, the color temperature problem in traditional photography has not been solved from the application and practical level. Of course, control color temperature except

Color filter, you need a temperature chart.

As the name suggests, "Color temperature" is related to temperature. Yes, Kelvin was the one that warmed the black iron to the 800° in the fire, and the iron block began to emit dark red. As the temperature rises, the color of the iron block begins to change from red to white, the higher the temperature, the greater the blue spectrum in the light emitted by the iron block, and the lower the red line spectrum. There is no need to dwell on this familiar process. However, this process is a lot of people mistakenly think that the temperature is related to the color temperature, that the temperature is color temperature, and misunderstood the true concept of color temperature is the change of the spectral composition of the object, the spectrum itself and no temperature, blue light than the red color temperature is high, because the proportion of Blu-ray in

A furnace temperature of molten steel high, or a blue fluorescent light temperature high? Many people say that molten steel is high. Wrong, the temperature as the color temperature. If in front of a blue color filter to see the molten steel, the temperature of the iron aqua Rose 2200K, the furnace molten steel temperature did not rise, just into our eyes the proportion of blue light increased. In a word, the color temperature is the test of light in the proportion of red-blue light a ruler, the blue color is high temperature, many red color temperature is low, and temperature-independent.

Figure 3-56

A furnace temperature of molten steel high, or a blue fluorescent light temperature high? Many people say that molten steel is high. Wrong, the temperature as the color temperature. If in front of a blue color filter to see the molten steel, the temperature of the iron aqua Rose 2200K, the furnace molten steel temperature did not rise, just into our eyes the proportion of blue light increased. In a word, the color temperature is the test of light in the proportion of red-blue light a ruler, the blue color is high temperature, many red color temperature is low, and temperature-independent.

In traditional photography, the term "white balance" is not generally used, and photographers may be unfamiliar. White balance Most of the application is to shoot TV, after the first dialogue, find the spot light white balance point and shoot, basically do not use a color filter to convert temperature. Digital camera, like television and video camera, introduces the concept of white balance and solves the problem of color temperature completely. First no longer need to color temperature conversion filter, so save a lot of expenses and carry the trouble. If you can grasp, the digital camera itself is a color temperature table, also save with a color temperature table. Second, the digital camera before the shooting, you can set up a variety of preset color temperature, daylight, cloudy, shadow, fluorescent, incandescent, flash, and so on, compared to the film only daylight and light temperature, there are more choices. Third, some models of digital cameras can be 100K units to preset changes in color temperature, compared to the precision of the filter. Four, can do white balance correction, with 5 Milde (micro-degree) for the unit adjustment, further improve its accuracy. Its five, can be based on the field of light "custom" white balance. The same as TV, White, catch the scene light. Its six, in post-production, through the image software can be the raw format of the color temperature of the file to reset, the accuracy reached 1K. The progress of digital technology finally makes 160 years to perplex people's color temperature problem thoroughly solves, truly understands and grasps the digital camera in the color temperature the outstanding sex and the advancement, you can not put down the hand again.

White balance is a variety of light color basic equal color mix, we see the light is white. Put a black and white gray color level in this light, we see is pure black and white gray, there will be no color. In the daylight, the digital camera color temperature is set to daylight, the photo shoot color must be accurate. Unfortunately, this is less perfect, the vast majority of the film we encounter is not the case, so we have to do white balance settings. Note that we cannot change the spectral proportions of the field light (that is, the color temperature), but we can change the balance point in the camera so that it matches the light on the scene, and the photograph is not biased. For example, the color temperature of the scene light is 5600K, the camera setting is also adjusted to 5600K (or use the flash, daylight setting), then the color restore will be accurate. If the scene light is stage lighting, color temperature 3000K, the proportion of red and yellow light spectrum is large. If the color temperature is set to 5600K, the spot light temperature is lower than the white balance point of the camera, the photograph will be more red. and the color temperature set 3000K, the camera's white balance datum point to the low color temperature offset, strengthen and increase the proportion of blue to offset the red and yellow, the results of the photo shoot color is no longer red, showing the normal color.

The camera automatically calculates the spectral proportions of the field light, and makes it achieve the full spectrum of the red, green, blue, and three primary colors that are required for panchromatic display.

Figure 3-57

By changing the spectral ratio of the camera to change the color temperature to correctly restore the picture, the majority of the film. In the digital camera does not exist on the film light and daylight type such a formula, digital cameras do not have the invariant color temperature. For each photo, you can use a different color temperature settings to match it, to achieve Zhang Zhang are accurate (figure 3-57).

Figure 3-58

The picture on the left is the Qinghai-Tibet Plateau. High mountains, sunshine, blue sky, white clouds, color temperature up to 7500K. The use of manual white balance set to 7500K, in fact, is to improve the red and yellow ratio, to suppress, balance the blue light, the results of the color of the photo is very accurate. The picture on the right is the sunset glow, using an automatic white balance, the camera measures a large amount of red light, so it enhances the blue, to suppress, balanced red, the result is not the head, the blue-violet Sky also got a very real performance (Figure 3-58). If set to 5400K, it is more able to enhance the proportion of red light. Understand the white balance of the truth, we can more flexible, artistic use of white balance principle to shape color, and not only in order to "color accurate" such a basic, low level of skill in the use of white balance.

Figure 3-59

As shown in Figure 3-59, when shooting the horse peak, you can use the automatic white balance to accurately reproduce the color of the time. To illustrate the problem, I changed the color temperature (which is exactly the same as the locale color temperature) by converting the image later in the raw format. It can also be considered that this is done in the early filming, do the same setting (5600K, set 5600K, color exactly correct). If the camera color temperature setting to 3800K, this time is equal to the field temperature increased by 1800K, blue is strengthened, so the photo appears blue.

Figure 3-60

Set the color temperature to 8000K, equal to the scene of the color temperature reduced by 2400K, Red has been extended, so the photo appears red (figure 3-60).

Figure 3-61

Note: This adjustment is left and right to move the midpoint, that is, change the camera's white balance light color ratio, the effect is the same as the color temperature value, the improvement is Garon, the lower is added blue (Figure 3-61). Like a gun, the star to the left, bullets will hit on the right. People generally form the impression that high color temperature blue, low color Wen Hong, this is the typical impression of thinking. The following is a typical scene of color temperature data, which lists some of the typical shooting scenes of the color temperature of the data. According to this setting, you can get basic and accurate colors. On this basis, the color effect can be reversed by adjusting the temperature value of the camera.

The range of color temperature of the camera basically includes all color temperature segment, use naturally is handy, but the shooting practice tells us, the camera's automatic white balance "automatic" ability is limited, that is to say it is not Pauta "sharp weapon". Figure 3-62 shows that the automatic white balance is only valid for 4500k~7000k color temperature values. Some camera manuals say they can reach 3000k~7000k, and in fact most of them don't.

The camera automatically white balance does not work, or manually set the color temperature to obtain a lack of precision, still dissatisfied, you can use a digital camera white balance drift, can be a very accurate color reduction.

Figure 3-63

Figure 3-63 is under the condition of color balance, the camera automatically has failed, using color offset to correct the color temperature of the experiment. At night, a local shooting of a computer table. The lighting condition is a 11 watt energy-saving daylight lamp on the roof. We know that the solar light spectrum is missing the red continuous spectrum, the photos are green and yellow. Using the camera is Canon 1Ds Markⅱ, ISO 800, F10, shutter 1s, I use the following conditions to shoot: automatic white balance, automatic white balance, manually set the color temperature to 2800, respectively, combining 2800 and white balance correction b9+m7, B9+M5, a6+m3, B9, etc. A total of 9 ways to shoot.

The use of automatic white balance photography has a serious bias (yellow green color), so the automatic white balance shot is ineffective, is completely failed to shoot. The custom white balance shot has a slight blue color bias. In the absence of a red light, the custom white balance uses too much blue. The rest of the white balance correction shows obvious corrective effects, of which the a4+m3 color temperature is the most accurate. In the screen, the front of the Apple chassis is gray, RGB is 128, pure gray. The colors of the other objects in the photo are also accurately displayed. In this bad light, using color offset to correct the color temperature, even to achieve "0 error" is really amazing. Digital camera to the color temperature control ability to reach an unprecedented height, without the trial of the study, may never be difficult to know the truth.

Figure 3-64

The same gray point (the gray color of the front of the chassis of the Apple Computer) is placed in the same color space for all color temperature settings. It is clear that, in addition to the 2800K+A4+M3, the rest are in an unbalanced state, the furthest is the automatic white balance, which is consistent with the previous experience of photography (Figure 3-64).

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