Page 60 - DCAP303_MULTIMEDIA_SYSTEMS

Multimedia Systems

notes Notes: MicroSoft Windows format, rarely supported elsewhere. Support 1, 2, 4, 8 and 32 bit colour
images.
format: Sun raster
platforms: Primarily Sun
owner: Sum MicroSystems

Notes: Only supported by Sun. Use RLE and either 8 bit greyscale or 24/32 bit colour.
format: XBM
platforms: Primarily X systems

owner: MIT X Corp
Notes: Specifically for X windows system bitmap routines used for cursors and icons.
format: XWD

platforms: Primarily X systems
owner: MIT X Corp
Notes: Screen save format under X windows. Implement black and white through to 24 bit direct
colour.
The TIFF is an international standard for storing and interchanging bitmaps
between applications and hardware platforms.

4.2 vector Drawing

In a vector drawing, you create control points. The lines in a vector drawing are created by the
software and join up the control points that the user has drawn. There are four control points in
the drawing above (three are little white squares; the last one is dark to indicate that it is being
worked on). There is far more to be explained about vector graphics.
Vector based applications such as CorelDraw and Adobe Illustrator treat images as collections of
vectors and shapes. A line would have a starting point, direction and length, a rectangle would
have a starting point, width and height, and circles would have a centre and radius, and so
on. After drawing a rectangle, you can go back and change its width and height, bring it to the
foreground or send it to the background, even after other shapes had been drawn on top of it
later. When saved to file, vector images also take up less disk space, for example, in the case of a
rectangle, the program is only storing four numbers no matter what its size: the x and y starting
point, plus the width and height. In comparison, a bitmap application would have to store colon
information for the 10,000 pixels that make up a 100 × 100 pixel rectangle.

advantages of vectors
• pretty much resolution-independent. It is possible to rescale up a whole chunk of animation
without the blockiness you would get from doing this with bitmaps
• for painting, you can specify that the bounding lines are automatically closed even when
not visible, so avoiding problems of paint flooding out
• shapes easily edited
• smaller output files for Internet use

• shapes can be made to animate automatically from one to another, providing they have the
same number of control points.

54 LoveLy professionaL University