Short for "pixel element", a pixel is the smallest unit of visual information in the digital world. Every digital photo, illustration, video, and game is constructed from pixels, which tend to be perfectly round or square. Below, we've outlined how the pixel was first developed, the information stored in a given pixel, and how these tiny units are assembled into detailed imagery.
What is a pixel?
First defined in the 1960s by Frederic C. Billingsley (an engineer at the Jet Propulsion Laboratory), the word "pixel" was used to explain how videos returned from NASA space missions. The engineering community had shortened "picture element", and their abbreviation became a common term. Like the periodic table of elements, pixels are the building blocks of images.
How do we measure pixels?
When more pixels are used to construct an image, it will look sharper and more realistic. Often, this pixel count is called "resolution", which is measured as "width" times "height". For example, an image with a 640x480 resolution is 640 pixels wide and 480 pixels tall. Likewise, digital cameras measure pixels using the "megapixel" standard, which is equal to one million pixels. This tells consumers how many million pixels the camera can capture, and you can learn the effective megapixel count by multiplying the pixel width and height.
What information do we find in a pixel?
Every pixel has unique color data, which is usually measured as RGB (red, green, blue) or CMYK (cyan, magenta, yellow, black). Having more storage capacity per pixel (measured in "bits", or bits per pixel) allows for more complex colors. If you only have one bit per pixel, that means the pixel can only contain one command, like a binary code. 0 or 1, black or white. With more bits per pixel, however, you increase the potential information for creating more elaborate colors, and this is known as "bit depth" or "color depth".
What is pixelation?
Megapixels are typically used to sell digital cameras, but they do come in handy if you want to blow up an image for printing. The more pixels you have to work with, the larger you can make a print without pixelation problems. When can see individual pixels with the naked eye, you're experiencing pixelation, and that means the camera resolution (or megapixel count) is not high enough for your needs. High quality prints need at least 240 pixels per inch (known as PPI or DPI), which equates to about 5 megapixels if you want to create an 8" x 6" print.
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