Simple Graphics

Graphics Used in PowerPoint, Web pages and others Basic Knowledge drawing change of colour, shape and others acquiring, video camera, scanning

Overview of Graphics Properties of color Essentially, color is light. Colors has three fundamental characteristics: hue, brightness, and saturation. Related to the three characteristics of light waves:wavelength (hue), amplitude (brightness), and purity (saturation).

Hue varies as you move around the cone in a clockwise or counter- clockwise motion on a plane perpendicular to the vector of the cone. Brightness varies as you move up or down the cone. The brightest color is at the top and the least bright color is at the bottom. Saturation changes as you move in toward the center of the cone or outward toward the surface. The least saturated colors are in the center while the most saturated colors are at the outside surface. Color space model

Properties of Pixels A pixel is the smallest unit of programmable color on a computer display or in a computer image. Every computer graphic is made up of a grid of pixels. When these pixels are painted onto the screen, they form an image.

Bitmap A bitmap is a collection of pixels that describes an image. enlarged

Bit depth is the number of bits used to store information about each pixel. The higher the depth, the more colors are stored in an image. 1-bit image (2 1 = 2 colors, black or white) 24-bit image (2 24 = colors) 8-bit image (2 8 = 256 colors)

Resolution Refers to the number of pixels per unit length on a monitor. It is usually measured in pixels per inch or dots per inch (dpi). Monitors come in a variety of resolutions. They can get as small as 320  200 pixels or as large as 1280  1024 pixels.

Vector graphics Vector graphics is defined by a sequence of commands or mathematical statements that place lines and shapes in a given two- dimensional or three-dimensional space. For example, instead of containing each bit of a line drawing, a vector graphic file describes a series of points to be connected.

A straight line may be defined as: In bitmap graphics In vector graphics line ([4,2],[15,2]), where [4,2] and [15,2] are coordinates of two points, and line() is a command drawing a line between two points

Different features between bitmap and vector graphics File size vector graphics smaller bitmap graphics larger Change of an image size (rescale) vector graphics: without loss of resolution bitmap graphics: with loss of resolution

Vector graphics Bitmap graphics File size 12 Kbytes File size 228 Kbytes

Some common file formats of bitmap graphics GIF: commonly used for Web graphics. It only supports 256 colors. With compression. JPEG: commonly used for Web graphics. It supports millions colors. With compression. BMP: Microsoft's native graphic file format. PICT: Apple Macintosh's native graphic file format. TIFF: primarily used for scanned images (mostly scanned photographs) and is suitable for desktop publishing applications.

Some common file formats of vector graphics EPS (Encapsulated PostScript): for the PostScript language. It uses a combination of PostScript commands and TIFF or PICT formats. DXF (Data Exchange File): created by AutoDesk. Almost all PC-based Computer-Aided Design (CAD) systems support DXF. WMF (Windows Metafile Format): for exchanging graphics between Microsoft Windows applications.