A texel, or texture element (also texture pixel) is the fundamental unit of texture space, used 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....

. Textures are represented by arrays of texels, just as pictures are represented by arrays of pixels.

Texels can also be described by image regions that are obtained through a simple procedure such as thresholding. Voronoi tesselation can be used to define their spatial relationships. This means that a division is made at the half-way point between the centroid of each texel and the centroids of every surrounding texel for the entire texture. The result is that each texel centroid will have a Voronoi polygon surrounding it. This polygon region consists of all points that are closer to its texel centroid than any other centroid.

Rendering With Texels

When texturing a 3D surface (a process known as texture mapping

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:...

) the renderer maps texels to appropriate pixels in the output picture. On modern computers, this operation is accomplished on the graphics processing unit

Graphics processing unit

A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...

.

The texturing process starts with a location in space. The location can be in world space, but typically it is in Model space so that the texture moves with the model. A projector function is applied to the location to change the location from a three-element vector to a two-element vector with values ranging from zero to one (uv

UV mapping

UV mapping is the 3D modeling process of making a 2D image representation of a 3D model.-UV mapping:This process projects a texture map onto a 3D object...

). These values are multiplied by the resolution of the texture to obtain the location of the texel. When a texel is requested that is not on an integer

Integer

The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...

 position, 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...

is applied.

Clamping & Wrapping

When a texel is requested that is outside of the texture, one of two techniques is used: clamping or wrapping. Clamping limits the texel to the texture size, moving it to the nearest edge if it is more than the texture size. Wrapping moves the texel in increments of the texture's size to bring it back into the texture. Wrapping causes a texture to be repeated; clamping causes it to be in one spot only.