Most people understand that pixels play some part in electronic imagery. You’ve probably bought digital cameras that pushed ever-higher MEGApixels, but the question that lingers is:
”What is a pixel?”
In simplest terms, it’s the most basic unit of color or value in an image. When you blow an image up on screen, pixels are usually defined as squares. Though you can’t see it from viewing distance, your display, whether an LCD or old-fashioned tube, only has three colors–red, green, and blue. They’re arranged together in groupings of three, one of each color. With LCDs, which have a specific pixel-count, each pixel is defined by one of these blocks of three. The most common type of color image is called 24 bit, meaning that each of the three colors has an 8 bit span of color value (8×3=24). 8 bits = 256 steps, from completely dark to fully bright. With each color having 256 steps, a single pixel, made of 3 colors, has 256 x 256 x 256 color variations (16.8 MILLION!).
When I said “fully bright”, I didn’t mean all the way to white. I mean that the sub-pixel element goes from off (black) to a bright red, bright green, or bright blue. The white you see on the screen is all three of these colors in their brightest state. Grab a magnifying glass or loupe and take a look!
This is RGB color, the way that light-projecting devices show color. Even if you’re working in CMYK (cyan, magenta, yellow and black) for print, it’s being displayed via RGB on your display. Conversely, if you print out an RGB photo in color, it will be converted to CMYK on the paper.
An image that occupies the CMYK color space has pixels that are defined by FOUR colors, each having 256 values, so you’d think you’d get a wider range of colors this way, but it’s just not so. I’ll leave those worries to the designers. The rest of you note that every snowy shot you take this winter with your digital camera is blasting the red, green and blue sub-pixels. Just stay away from the snow that’s only made up of the red and green subs (that’s YELLOW!). - j
Author Bio:
Jay Scheuerle, our Creative Services department's Art Director, could have been a doctor, but chose to work amongst us mere mortals. An even-tempered designer and telescope enthusiast who's been shutting out co-worker chatter for more than nine years, Jay sees the angles others don't.
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