For this inaugural post to my new blog I thought I’d offer a little tongue-in-cheek analogy to paint a broad brush illustration about raw format digital images. I’ll get into more detail in upcoming posts. Welcome to The Way Eye Sees It.
For all the incredible technology packed into digital cameras, there is one missing element that will remain missing perhaps forever. The missing element? The combination of human eyesight and the brain’s image processor called the Visual Cortex.
The Visual Cortex is located in the lower rear of your brain. This is where the real color perception magic happens; magic that goes way beyond the elementary interpretation capabilities of most cameras on the planet. While your camera may feature some form of “intelligent” or “Automatic” White Balance features, they cannot accurately analyze every lighting condition.
Your brain is very forgiving. It focuses light through your eyes and automatically color corrects almost every lighting condition and color cast. Within seconds, your eyes and brain adjust to a wide range of lighting intensities and color casts, delivering very believable images to your mind. And it all happens instantly and automatically, without you even realizing it. No white balance to set, no color shifts to neutralize no highlight and shadow tones to assign. Your brain’s magic intuition and forgiving nature do a crazy-good job of color correction for you.
Your camera records colors a bit more simply. It simply captures a blast of light, interpreting it through various pre-set color filters collectively known as White Balance. The White Balance options include Daylight, Shadow, Cloudy, Tungsten, Flash, etc. Each of these options simply add defined color casts to the light being captured. Your camera’s default setting is Daylight, which sets the White Balance to a pre-defined color temperature of 6500° Kelvin, or the perceived color of sunlight in the daytime. When you choose Shadow or Cloudy mode, the camera shifts the colors toward yellow to compensate for the natural bluish temperature of the indirect sunlight.
Most cameras offer to capture images in a file format called “raw.” Raw format simply captures the light without any color influence at all; hence the name “raw.” Raw images are so raw that the color temperature of the light hasn’t been defined, and therefore, isn’t even visible! When you capture an image in raw mode, the image you see on your camera’s LCD display screen isn’t the actual raw image, it is but one interpretation of that image, determined by the camera’s current mode and exposure settings expressed as a JPG file. Think of this display as simply a mold into which all that light was poured. But it is merely one of countless molds that the raw image can be shaped by.
My mom used to make cookies for Christmas when I was a kid. She rolled-out the cookie dough and used the coolest shaped cookie cutters that produced a variety of different shaped cookies. Each mold she chose shaped the cookie dough uniquely. After the cookies were baked, she decorated each one uniquely. All those cookies came from the same raw cookie dough but they all looked different. If you think about it, raw photographic files are like raw cookie dough.
A raw image is simply a record of unfiltered spectral information reflecting from a subject. It is simply everything the camera sensor recorded when the shutter was open. This raw file is light “dough” that can be shaped in a variety of ways. Only when that information is filtered through a defined parameter can it be seen. The raw information entering the lens doesn’t get filtered by any of the camera modes mentioned above. And because all those modes are bypassed when the image is captured, you get to determine how that light ingredients are defined- after the shot has been captured.