Image 4. An example of Computer animation produced using Motion capture
Unit 20: Graphics and Design
Computer Graphics
The study of computer graphics is a sub-field of computer science which studies methods for digitally synthesizing and manipulating visual content. Although the term often refers to three-dimensional computer graphics, it also encompasses two-dimensional graphics and image processing. The term computer graphics represents almost everything on computers that is not text or sound. Today nearly all computers use some graphics and users expect to control their computer through icons and pictures rather than just by typing. The term Computer Graphics has several meanings:
• the representation and manipulation of pictorial data by a computer
• the various technologies used to create and manipulate such pictorial data
• the images so produced, and
•the sub-field of computer science which explores methods for digitally synthesizing and manipulating visual content.
Today computers and computer-generated images have a great impact on our daily life. Computer imagery can be found on television, in newspapers, in weather reports, and during surgical procedures, so computer graphics can be used in many disciplines. A well-constructed graph can present complex statistics in a form that is easier to understand and interpret. Such graphs are used to illustrate papers, reports, theses, and other presentation material.
Exercise 1. Read the text and answer these questions.
What does the term computer graphics stand for?
Which people might use computer graphics professionally? What would they use themfor?
Have you ever used computer graphics? What for?
D computer graphics
Image 1. Raster graphic sprites (left) and masks (right)
2D computer graphics are mainly used in applications that were originally developed upon traditional printing and drawing technologies, such as typography, cartography, technical drawing, advertising, etc. Two-dimensional models are preferred because they give more direct control of the image than 3D computer graphics, whose approach is more akin to photography than to typography.
3DComputer graphics
Vector graphics
2DComputer graphics
Computer animation
Vector graphics
Image 2. Example showing effect of vector graphics versus raster graphics.
Vector graphics represents the use of geometrical primitives such as points, lines, curves, and shapes or polygon (s), which are all based upon mathematical equations, to represent images in computer graphics. Vector graphics formats are complementary to raster graphics, which is the representation of images as an array of pixels that are used for the representation of photographic images. Vector graphics are good for excluding unnecessary detail. Detail can be added or removed from vector art. Vector illustrations can have their own colours, allowing artists to achieve desired results .In computer graphics, vectorizationrefers to the process of using software and hardware technology/services to convert raster graphics into vector graphics. A raster graphicsimage or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of colour, viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats.
Rasterizationor Rasterisationis the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image (pixels or dots) for output on a video display or printer, or for storage in a bitmap file format.
Image 3. Imagine the smiley face in the top left corner as an RGB bitmap image. When zoomed in, it might look like the big smiley face to the right. Every square represents a pixel. Zooming in further, the individual pixels can be analyzed, with their colours constructed by adding the values for red, green and blue.
D computer graphics
3D computer graphics in contrast to 2D 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. Such images may be for later display or for real-time viewing.3D computer graphics are often referred to as 3D models. However, there are differences. A3D model is the mathematical representation of any three-dimensional object (either inanimate or living). A model is not technically a graphic until it is visually displayed. Due to3D printing, 3D models are not confined to virtual space. A model can be displayed visually as a two-dimensional image through a process called 3D rendering,
or used in non-graphical computer simulations and calculations.
Computer animation
Image 4. An example of Computer animation produced using Motion capture
Computer animation is the art of creating moving images via the use of computers. It is a subfield of computer graphicsand animation. Increasingly it is created by means of 3Dcomputer graphics, though 2D computer graphics are still widely used for stylistic, low bandwidth, and faster real-time rendering needs. To create the illusion of movement, an image is displayed on the computer screen then quickly replaced by a new image that is similar to the previous image, but shifted slightly. This technique is identical to the illusion of movement in television and motion pictures.