Pixel

• A pixel is a smallest element of a image.
• A pixel is also known as PEL.
• Pixel is a variable element, in digital pixel is a physical point which change colors according to image represented on screen.
• Each pixel correspond to any one value. In an 8-bit gray scale image, the value of the pixel between 0 and 255.

Grey level

The value of the pixel at any point denotes the intensity of image at that location, and that is called grey level.

Total no of pixel = Total no rows * Total no of column

Resolution of computer monitors

• Computers can use pixels to display an image, often an abstract image that represents a GUI.
• The resolution of this image is called the display resolution and is determined by the video card of the computer.
• LCD monitors also use pixels to display an image.

Bit per pixel

• The number of distinct colors that can be represented by a pixel depends on the number of bits per pixel (bpp).
• 1 bpp, 21 = 2 colors (monochrome)
• 2 bpp, 22 = 4 colors
• 3 bpp, 23 = 8 colors
• 8 bpp, 28 = 256 colors
• 16 bpp, 216 = 65,536 colors ("High color" )
• 24 bpp, 224 = 16,777,216 colors ("True color")

Subpixel

• The pixel grid is divided into single color regions to displayed or sensed the different colors when viewed from distance.
• The subpixels can be ignored, with full-color pixels being treated as the smallest addressable imaging element.
• The subpixels can be included in rendering calculations, which requires more analysis and processing time, but can produce apparently superior images in some cases.

Megapixel

• A megapixel (MP) is a million pixels; the term is used not only for the number of pixels in an image, but also to express the number of image sensor elements of digital cameras or the number of display elements of digital displays.