Computer Graphics – Concepts and Principles

Representing and manipulating an image data by a computer is called Computer Graphics. It is shortly referred to as CG. The development in this field has created a drastic change in media like animation as well as video game industry. Most of the mind blowing effects in cinemas are the result of the advancement in Computer Graphics. Here let us discuss some of the basic concepts and principles in CG.


An image of picture is nothing but an art work that looks like a person or a physical object. This representation of a physical object or person may be either two dimensional or three dimensional. Optical devices such as lenses, mirrors, cameras are used to capture such images. A digital image is a representation of a 2-dimensional image in binary format, that is, as a sequence of 1s and 0s. Raster and vector images are the two types of digital images. But the raster images are the most commonly used.


The resolution of a picture is often based on the pixel counts of the image. When the image is seen in an enlarged portion, you can notice the individual pixels as squares. Generally pixels are arranged in an ordinary 2-dimensional grid and dots or squares are often used to represent them. Each and every pixel differs in color systems and intensity. A single pixel can be considered as a sample of an image. Increase in pixel count, that is, increase in samples, results in the exact representation of the original picture.


Combination of text, illustration and color is called Graphics. They are the visual representation of any object on the surface such as computer screen, wall, paper etc. Photographs, drawings, maps, diagrams are some of the examples. The prime objective of the Graphics is to create a style that is unique or an effective communication associated with cultural elements.


Using computer programs, an image can be generated from a model. This process is called Rendering. The model contains viewpoint, geometry, texture, lighting etc. The image may be a raster graphics image or digital image. To produce the final video output, this process is used for the calculating effects in a video editing file.

3D projection:

This kind of projection is used extensively and most preferably in CG, drafting and engineering. It is a method of mapping 3 dimensional points to a 2 dimensional plane. At present only 2-dimensional plane is used for displaying graphical data.

Ray tracing:

Using this technique an image can be generated by tracing the path of light ray through pixel in an image plane. It has the ability to produce images with extreme photorealism at a greater computational cost.


It refers to depicting illustrations or depth in 3D models in different darkness levels. There are several techniques of shading where the perpendicular lines are drawn in a crisscross pattern to shade an area.

Texture mapping:

This method is used for adding surface texture, color or any detail to a 3D model or a computer-generated graphic. A texture map can be mapped to the surface of a shape, say polygon.