Pixel

Last Updated: August 31, 2020

Definition - What does Pixel mean?

A pixel is the smallest unit of a digital image or graphic that can be displayed and represented on a digital display device.

A pixel is the basic logical unit in digital graphics. Pixels are combined to form a complete image, video, text, or any visible thing on a computer display.

A pixel is also known as a picture element (pix = picture, el = element).

Techopedia explains Pixel

A pixel is represented by a dot or square on a computer monitor display screen. Pixels are the basic building blocks of a digital image or display and are created using geometric coordinates.

Depending on the graphics card and display monitor, the quantity, size and color combination of pixels varies and is measured in terms of the display resolution. For example, a computer with a display resolution of 1280 x 768 will produce a maximum of 98,3040 pixels on a display screen.

The pixel resolution spread also determines the quality of display; more pixels per inch of monitor screen yields better image results. For example, a 2.1 megapixels picture contains 2,073,600 pixels since it has a resolution of 1920 x 1080.

The physical size of a pixel varies, depending on the resolution of the display. It will equal the size of the dot pitch if the display is set to its maximum resolution, and will be larger if the resolution is lower since each pixel will use more dots. Because of that, individual pixels may become visible, leading to a blocky and chunky image defined as “pixelated”.

Pixels are uniformly arranged in a two-dimensional grid, although some different sampling patterns are available. For example, in LCD screens the three main colors are sampled at different locations of a staggered grid, while digital color cameras use a more regular grid.

In computer monitors, pixels are square-shaped, meaning that their vertical and horizontal sampling pitches are equal. In other systems such as the anamorphic widescreen format of the 601 digital video standard, the shape of a pixel is rectangular.

Each pixel has a unique logical address, a size of eight bits or more and, in most high-end display devices, the ability to project millions of different colors. The color of each pixel is determined by the specific blending of the three main components of the RGB color spectrum.

Depending on the color system, a different number of bytes can be allocated for specifying each color component of the pixel. For example, in 8-bit color systems, only one byte is allocated per pixel, limiting the palette to just 256 colors.

In the common 24-bit color systems used for nearly all PC monitors and smartphone displays, three bytes are allocated, one for each color of the RGB scale, leading to a total of 16,777,216 color variations. A 30-bit deep color system allocates 10 bits each of red, green, and blue for a total of 1.073 billion color variations.

However, since the human eye cannot discriminate more than ten million colors, more color variations do not necessarily add more detail, and may even lead to color banding issues.

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