In computer graphics

Computer graphics

Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....

, pixelation (or pixellation in British English

British English

British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

) is an effect caused by displaying a bitmap

Bitmap

In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...

 or a section of a bitmap at such a large size that individual pixel

Pixel

In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

s, small single-colored square display elements that comprise the bitmap, are visible to the eye. Such an image is said to be pixelated (pixellated in the UK).

Early graphical applications such as video games ran at very low resolution

Image resolution

Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....

s with a small number of colors, and so had easily visible pixels. The resulting sharp edges gave curved objects and diagonal lines an unnatural appearance. However, when the number of available colors increased to 256, it was possible to gainfully employ antialiasing to smooth the appearance of low-resolution objects, not eliminating pixelation but making it less jarring to the eye. Higher resolutions would soon make this type of pixelation all but invisible on the screen, but pixelation is still visible if a low-resolution image is printed on paper.

In the realm of real-time 3D computer graphics

3D computer graphics

3D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images...

, pixelation can be a problem. Here, bitmaps are applied to polygons as texture

Texture mapping

Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...

s. As a camera approaches a textured polygon, simplistic nearest neighbor texture filtering

Texture filtering

In computer graphics, texture filtering or texture smoothing is the method used to determine the texture color for a texture mapped pixel, using the colors of nearby texels . Mathematically, texture filtering is a type of anti-aliasing, but it filters out high frequencies from the texture fill...

 would simply zoom in on the bitmap, creating drastic pixelation. The most common solution is a technique called pixel interpolation that smoothly blends or interpolates the color of one pixel into the color of the next adjacent pixel at high levels of zoom. This creates a more organic, but also much blurrier image. There are a number of ways of doing this; see texture filtering for details.

Pixelation is a problem unique to bitmaps. Alternatives such as vector graphics

Vector graphics

Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent images in computer graphics...

 or purely geometric polygon models can scale to any level of detail. This is one reason vector graphics are popular for printing — most modern computer monitors have a resolution of about 100 dots per inch, and at 300 dots per inch printed documents have about 9 times as many pixels per unit of area as a screen. Another solution sometimes used is algorithmic textures, textures such as fractal

Fractal

A fractal has been defined as "a rough or fragmented geometric shape that can be split into parts, each of which is a reduced-size copy of the whole," a property called self-similarity...

s that can be generated on-the-fly at arbitrary levels of detail.

Deliberate pixelation

In some cases, the resolution of an image or a portion of an image is lowered to introduce pixelation deliberately. This effect is commonly used on television news shows to obscure a person's face or to censor nudity

Nudity

Nudity is the state of wearing no clothing. The wearing of clothing is exclusively a human characteristic. The amount of clothing worn depends on functional considerations and social considerations...

 or vulgar

Vulgarity

Vulgarity is the quality of being common, coarse or unrefined. This judgement may refer to language, visual art, social classes or social climbers...

 gestures, and is also used for artistic effect. This effect is called pixelization

Pixelization

Pixelization is a video- and image-editing technique in which an image is blurred by displaying part or all of it at a markedly lower resolution. It is primarily used for censorship...

. Making pixels easily visible is also a main feature in pixel art

Pixel art

Pixel art is a form of digital art, created through the use of raster graphics software, where images are edited on the pixel level. Graphics in most old computer and video games, graphing calculator games, and many mobile phone games are mostly pixel art.- History :The term pixel art was first...

 which is where the graphics are made in low resolutions for effect.

External links

• Zooming Without Pixelation, digital camera advice by Mark Coffman
• Pixelization of a Font by Stephen Wolfram
  Stephen Wolfram
  Stephen Wolfram is a British scientist and the chief designer of the Mathematica software application and the Wolfram Alpha computational knowledge engine.- Biography :...
  
  , The Wolfram Demonstrations Project.