Pixel, short for picture element, is the smallest unit in a graphic display or digital image. Computer displays are made up of a grid of pixels. Each pixel is made up of red, blue, and green lighting elements that are used in different combinations and intensities to make millions of different colors.
How do pixels work?
Pixels are the vehicle for transforming binary code data into an image on a screen. Each pixel in an RGB monitor is sent a piece of code that tells it how to display a certain color. Because each pixel has red, green, and blue lighting elements, the code is made up of a triplet of eight-digit numbers written in binary code. This tells each of the three color elements at what intensity to display, and when all three colors are combined, they display the desired color. Each pixel displays one color, and the colors together make an image.
Resolution vs. pixel density
When talking about image or screen quality, the term resolution is often used. Screen resolution can be defined as the number of pixels on a screen. For example, a 13-inch Macbook Air has a resolution of 2560 x 1600, which means that the screen is made up of over 4,000,000 pixels. The higher the resolution, the higher the image quality.
While the resolution is important to consider when measuring screen quality, it is also important to consider the pixel density. Pixel density is either measured in PPI (pixels per inch) or PPC (pixels per centimeter). For example, if you look at a photo on an iPhone and on a movie screen, both with 1792 x 828 resolution, the iPhone image will have a better quality because the PPI is higher on the iPhone screen. When the picture is blown up on a movie screen with the same resolution as the iPhone, the image will be pixelated.