Page 9 - DCAP504_Computer Graphics

Computer Graphics

Computer graphics covers many important elements in the field of computer science, such as the
processing of images, interaction with images, representation of images, and display of images. Due to
these important elements, today, computer graphics have become an important aspect of our daily
lives. Computer graphics is used in almost all the fields today, such as games, weather reports, or all
kinds of medical investigation and surgical procedures.

1.1 Image Files
An image is made up of a rectangular grid of pixels. It has a definite height and a definite width
counted in pixels.
An image file refers to any pictorial representation that is already stored in the computer memory. An
image file format refers to the particular format in which an image file is stored. Generally, a file format
stores the number of rows and columns of image pixels, in the header information of the image file.
You can save an image in different file formats. The most commonly used image file formats are TIFF,
JPG, and GIF, which are very important in the process of printing, process of scanning and Internet use.

In Internet browsers, TIF cannot be used.

It is very important to know that a digital image is normally encoded in the form of a binary file for the
function of transmission and storage.

Did you know? The pixels that represent an image are structured as a grid (columns and rows), where
every single pixel comprises numbers that depict the degree of color and brightness.

Figure 1.1 depicts a typical organization of image files with reference to information encoded in an
image file.

Figure 1.1: Typical Image File Organization

As shown in the figure 1.1, a typical image file mainly consists of two parts, namely, header and image
data. At the beginning of the header, a binary code or American Standard Code for Information
Interchange (ASCII) string identifies the format being used along with the version number. The height
and width of the image are specified in the number of pixels. The most common image type includes
black and white (1 bit/pixel), 8 bit gray scale (256 levels with the gray axis), 8 bit color (lookup table),
and 24 bit color.
The main function of an image data format is that it specifies the order, in which, the pixel values are
stored in the image data section. Generally, the left to right and top to bottom orders are used, and

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