Pixel

Pixel

One of my first pictures that I took using reverse focusing. This will create an astonishing magnification with very very shallow depth of field. But the downside is just that it only allows little light to pass through and focus distance is really for macro range. This is a shot of my Sister's laptop lcd. Lcd is made up of pixrls consisting of red, green and blue (RGB). this will combine is different proportion to give millions of colours and shades.

A pixel is generally thought of as the smallest complete sample of an image. The definition is highly context sensitive; for example, we can speak of printed pixels in a page, or pixels carried by electronic signals, or represented by digital values, or pixels on a display device, or pixels in a digital camera (photosensor elements). This list is not exhaustive, and depending on context there are several synonyms that are accurate in particular contexts, e.g. pel, sample, byte, bit, dot, spot, etc. We can also speak of pixels in the abstract, or as a unit of measure, in particular when using pixels as a measure of resolution, e.g. 2400 pixels per inch, 640 pixels per line, or spaced 10 pixels apart.

The measures dots per inch (dpi) and pixels per inch (ppi) are sometimes used interchangeably, but have distinct meanings especially in the printer field, where dpi is a measure of the printer's resolution of dot printing (e.g. ink droplet density). For example, a high-quality inkjet image may be printed with 200 ppi on a 720 dpi printer.

The more pixels used to represent an image, the closer the result can resemble the original. The number of pixels in an image is sometimes called the resolution, though resolution has a more specific definition. Pixel counts can be expressed as a single number, as in a "three-megapixel" digital camera, which has a nominal three million pixels, or as a pair of numbers, as in a "640 by 480 display", which has 640 pixels from side to side and 480 from top to bottom (as in a VGA display), and therefore has a total number of 640 × 480 = 307,200 pixels or 0.3 megapixels.

The pixels, or color samples, that form a digitized image (such as a JPEG file used on a web page) may or may not be in one-to-one correspondence with screen pixels, depending on how a computer displays an image.

Many display and image-acquisition systems are, for various reasons, not capable of displaying or sensing the different colour channels at the same site. This approach is generally resolved by using multiple subpixels, each of which handles a single colour channel. For example, LCD displays typically divide each pixel horizontally into three subpixels. Most LED displays divide each pixel into four subpixels; one red, one green, and two blue. Most digital camera sensors also use subpixels, by using coloured filters. (CRT displays also use red-green-blue phosphor dots, but these are not aligned with image pixels, and cannot therefore be said to be subpixels).

(courtesy wikipedia.com)