Pixel

• Pixel is a smallest element of a picture represented on the screen.
• Pixel is a variable element. In digital imaging pixel is a physical point which looks like a dot on the screen which changes color according to image represented on the screen.

• In color imaging systems a color is typically represented by three or four component intensities such as red, green and blue.

Sampling Patterns:

• For convenience pixels are normally arranged in a regular two-dimensional grid.

• LCD screens typically use a staggered grid where the red, green and blue components are sampled at slightly different locations.

Resolution of computer monitors:

• Computers use pixels to display image often an abstract image that represents a GUI (Graphical User Interface).
• The resolution of the image is called the display resolution and is determined by the video card.
• Each pixel is made up of number of traids with the number of these traids determines the resolution.

Bits per Pixel:

• The number of distinct colors that can be represented by a pixel depends on the number of bits per pixel (bpp). 
• A 1 bpp image uses 1-bit of each pixel so each pixel can be either on or off. 
• Each additional bit doubles the number of colors available, so a 2 bpp image can have 4 colors and 3 bpp image can have 8 colors.
• 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 ("Highcolor" )
• 24 bpp, 2²⁴ = 16,777,216 colors ("Truecolor")    

Sub Pixels:

For systems with sub pixels two different approach can be taken:-

• The sub pixels can be ignored with full color pixels being treated as the smallest addressable image element or 
• Sub pixels can be included in rendering calculations, which requires more analysis and processing time, but can produce apparently images in some cases.

Mega Pixel:

• A mega pixel is a million pixels, the term used not only for the number of pixels in a image but also the number of image sensor elements of digital cameras.
• If a camera makes a 2048 X 1536 pixel image (3,145,728 pixels) typically uses a few extra rows and columns of sensor elements and is commonly said to have 3.2 Mega Pixels.

Notes: