White Balance Photography Assignment Color


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Color is a visual property of perception. Camera chip interprets the light that passes through the lens in a similar way as our brain interprets the light passing through our eyes. Our perception of color is a result of the journey undertaken by light. Light travels from the light source onto an object and then it bounces off the object and continues to travels through our eyes onto receptors. Then information received is processed by the brain. The brain, being very considerate of our psyche, it balances the color of the light to a white point (simulating daylight). The camera works in a similar manner as the human eye + brain: the light enters the lens and falls onto sensor and then the data gets processed and the software/firmware assigns corresponding values based on camera settings. (Note: when shooting in RAW, white balance can be re-assigned in a raw processing software.)

Color is determined by many variables, the main ones are:

1. The Light source:

Human beings on planet earth have been exposed to the single light source called the Sun for millions of years. The first time humans where able to produce an alternative light source (fire), according to the most recent study, was about 790,000 years ago (oh yeah, check out our previous tutorial on photographing fire)

Then in the early 19th century, an incandescent light bulb came into existence, followed by fluorescent tube by the end of century, followed by halogen bulb, and flash tubes around 1930s. It is fascinating, to me, that the human brain has the ability to automatically tweak any light source to a white point. This is why people are able to observed the environment around them without any dramatic change. If our brain was set to a fixed white balance setting, Thomas Edison would have died a poor man.

Sun:The color temperature of the sunlight on a clear day generally varies from 2000 degrees Kelvin at sunrise to 5400K by noon and back to 2000 degrees at sunset while in the shade color temperature stays at about 8000 degrees. As human brain itself is set to (AWB) automatic white balance we do not notice the change so dramatically.

Incandescent bulbs (the famous clamp lamp) project the light at color temperatures ranging from 2650 K to 3200 K degrees, depending on wattage. Flash Strobe projects light at 4800 to 5500 – depending on the brand and power settings. High end professional strobes maintain the same color temperature of 5400 K (daylight) at any power setting.

2. Substances the Light Goes Through Before It Hits the Object.

For example, the sun emits the light at 5780k. That light then passes through layers of gasses of the atmosphere and clouds and changes to the color from 2000 to 30000 K. With artificial light sources color or color-correcting gels can be used to alter the temperature of the light.

3. Properties of the Object.

Texture determines how much light is being absorbed and how much light will bounce off a surface. While pigments and other properties determine the wavelengths of the bounced light and thus determines the color in a spectrum.

4. The substances that light goes through on the way from the object to the eye (or lens).

When photographing outdoors there are various factors that can alter the color such are Haze, Evaporation, Humidity, and Air pollution (in big cities). This can be further adjusted by on lens filters. A “UV” filter is most commonly used.

5. Type of lens and its quality.

Better quality (more expensive) lenses allow the light to travel through the glass without farther fogging or softening and provide additional filtration of ultra violet light.

6. Receptors / Digital Sensor.

When the light finally passed through our eyes receptors pass the information to the brain. About 5% of population (mostly males) lack certain receptors and are blinded to certain colors.

7. Brain / Computer:

Our brain processes information received and balances colors to a white point. It can also alter some colors and saturation if it is under the influence of psychedelic substances….oh good old days…. On a computer or in camera the data that corresponds to color can be altered by the camera settings or if shooting RAW by raw processing software or pixel editor (such as Photoshop)

Conclusion:

Since many variables influence the color of light, the light temperature will vary and be inconsistent and thus camera’s automatic white balance or predetermined settings (daylight, shade, florescent, incandescent etc..) might not provide accurate results. Custom White Balance allows the photographer to tell the camera, what is in truth, the white point.

How do you color-correct your images?please share your tips.

Assignment: try to color balance your images as accurately as possible. If you run into trouble just post your image here (using share your shot feature) in comments and we will help you out.

Have you ever taken a photo where the colours appear all wrong? For instance with a strong blue or orange tint (what is called a colour cast)? If you ever took a picture at night, it most probably happened to you a fair few times. This is a case of wrong white balance: the colours are not well balanced with each other, and casts appear. One particularly visible consequence is that white is not pure white anymore, but slightly yellow or blue instead.

This is because not all light is created equal, and some have warmer components than others (i.e. they have stronger yellow and reds than blue and greens). We speak of light temperature, of which there is an actual scientific definition, though it’s not worth getting into this now. For instance, tungsten light (the usual incandescent lamps) appears much warmer than daylight sun, which is why it appears so yellow on night photographs. Fluorescent lights, on the other hand, are quite cold, explaining the “sterile” and inhuman look some offices have.

Unless it is extremely basic, your camera probably has a White Balance setting (often abbreviated in WB). Its usual modes are Auto (abbreviated AWB), Sunny, Shade, Fluorescent and Tungsten (with standard icons, see below). Choosing one other than Auto will tell the camera how to compensate for the current light conditions so that a white object really appears white.

Film photographers have it much harder, as the only two ways of controlling white balance are to use a different film (some are known to be warmer than others) or to use coloured filters.

Despite its somewhat technical nature, white balance is a very important creative tool, as we tend to have instinctual reactions to the set of colours used in an image: warm tones convey an idea of comfort, softness, happiness, while cold colours are usually distant, hostile and cruel. If it fits your vision, you should not hesitate to introduce (subtle) colour casts to enhance the message you are trying to convey.

Choosing the right white balance may seem like a difficult task. After all, our brain is so good at compensating colour casts that we rarely notice if our current environment is more of a tungsten or a fluorescent light. There are however very good news for digital photographers: if you shoot raw instead of jpg (which we will discuss in more detail in a later lesson), you will be able to set white balance after the shoot, in post-processing, with no loss of image quality. In other words, you do not need to worry about white balance at all until you get back to your computer, at which point, as we will see in a moment, it is a much easier task.

If you want to get white balance right in camera (because you are shooting jpg, or because you want to spend as little time on the computer as possible), you have three possibilities:

  • You can trust the camera with the job and shoot in AWB. Most modern cameras will do a pretty good job as long as the conditions are reasonable, but all bets are off when you add mixed, complicated lighting. In short, you can probably forget about WB as long as you are shooting natural light by day, but you should be paying attention once you add any kind of artificial light.
  • You can try to guess what the light composition is and set the camera WB in the relevant mode. It helps to also know that “fluorescent” means the image will get warmer, while “tungsten” means it will get cooler – using the screen, you can use trial and error until you get a WB that corresponds to your vision. This is quite cumbersome and you will occasionally forget to reset your WB mode between shoots, but with enough practice, it can work well.
  • Finally, you can use a grey card to create your own WB mode. This is definitely the most accurate method, but it is also the most complex and time consuming. What you are doing is take a photo of a neutral gray piece of paper (anything will do, really, but many stores will be happy to sell you overpriced pieces of cardboard), then tell the camera that this should be its new reference point for WB from now on. Obviously, you will need to repeat this process every time the lighting changes.

If, on the other hand, you shoot raw, you can adjust WB in post. There are several ways to do this, one of which being to use the same modes than your camera or to use sliders to set light temperature to the exact values you want. However, the easiest method of all is simply to pick out a neutral part of the image and tell the software “this should be neutral, please adjust white balance accordingly”. As long as you can find an object that should be some shade of grey, you obtain results just as accurate as if you had used the custom WB procedure. Of course, it will occasionally happen that you can’t find anything neutral, and you might have to resort to the sliders and your own memory of the scene. To prevent this kind of scenarios, some photographers do take a picture of a grey card at the beginning of an important shoot, in order to have a point of reference.

Assignment

This assignment is here for your to play with your white balance settings. It helps if your camera has the ability to shoot raw: for each part of the assignment, take each photo in both jpg and raw (you can use the raw+jpg mode found on most cameras) and try the post processing on both, comparing the results at the end. You will also need a grey card, anything white or grey which isn’t too translucent will do just fine.

For the first part, go outside by day. It doesn’t matter if the weather is cloudy or sunny, as long as it’s natural light. First, set your WB mode to Auto and take a photo. Now do the same in every WB mode your camera has. Don’t forget to take a shot of the grey card.

Repeat the exercise indoor, in an artificially lit scene. First, try it with only one type of light (probably tungsten), then, if you can, with both tungsten and fluorescent in the same scene.

Once you have all the images, download them on your computer and open them in a software which can handle basic raw conversion. Observe how different all the images look, and try to get a correct WB of each one just by eye and by using the temperature sliders. Now use the grey card shots to find out the real temperature and use this to automatically correct all the images of each shoot (there usually is a “batch” or a copy-and-paste feature for this). Finally, notice how raw files should all end up looking exactly the same, while the jpg files will be somewhat degraded in quality.

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