Understanding Graphics for Creating Computer-Based Multimedia Projects & Web Pages Adapted by Helen Mongan-Rallis from presentation by Andrea Pokrzywinski (used with permission for Educ 5415)
Monitor Colors RGB
1 Bit Black and White
24 Bit Color
216 Web Safe Colors
Macintosh Computers and Window computers have different color indexes of 256 colors
Web safe: only 216 colors that match perfectly on the monitor when seen on both platforms
Thus, for reliable graphic design, use only web safe colors
Graphics files take up a lot of memory
Causes sluggish performance on web sites with graphics
Two types of graphic compression formats have been become standard for web use.
Joint Photographic Experts Group -A compression standard developed for still images.
JPEG compression is recommended for photographic -style images and continuous -tone images (e.g. used for backgrounds).
JPEG Compression is Variable 42K 32K 36K
JPEG images pixelate as they are enlarged
Graphics Interchange Format
A graphic compression format developed by CompuServe to allow graphics to load quickly on easily through a network.
Best used with flat graphics and such as logos and drawings.
GIF - Indexed Color Limited to 256 Colors
GIF vs. JPEG JPEG=15,343 bytes GIF=26,979 http://www. rit . edu /~bdb7236/ mmwww / picthis .html
Gif vs JPEG JPEG=42,268 bytes GIF=21,507 bytes http://www. rit . edu /~bdb7236/ mmwww / picthis .html
Gif files will allow you to set one color to be transparent. This means it will allow the web pages background to be viewed through this color.
Transparent Not Transparent
Placing transparent objects on background colors that match the transparency color will prevent haloing seen in the previous slide.
Interlacing allows the picture to gradually fill in by adding lines top to bottom and repeats this till the image is complete.
Standard format fills from top to bottom.
Interlacing allows the viewer to see a preview of the entire image before it finishes downloading .
The image on the UMD Psychology dept. web site at http://www.d.umn.edu/psychology/people/index.html is interlaced. Notice how it loads…
Anti-Aliasing smoothes the edges of a graphic.
DPI - Screen Resolution
Monitors read 72 dots per inch in resolution
Thus there are about 5,200 dots per square inch.
Printed documents usually use 150 dpi or higher with 1, 440, 000 dots per square inch.
For web photos, set your image resolution to 72 dpi.
Sony Mavicas are set to take 72 dpi photos
72 pixels to an inch.
Pixels are the standard measuring tool for computer monitors.
Web page designers design with for a monitor view of 640 pixels wide and 480 pixels in height as a standard.
This allows for the lowest common denominator in monitors to view the entire screen. This will change with advances in technology.
Hexadecimal Color Codes Web colors are coded in six digit code combining numbers and letters. You can find the codes for web safe colors on web sites for graphics editors or it will be built into sophisticated web graphic editing programs like fireworks. #33CC00
Draw a graphic from scratch
Scan a picture with a scanner
Draw using graphic applications (e.g. PhotoShop, AppleWorks Draw, or PowerPoint draw tools)
Copying from the Web
Free Web Art Site
http://www. mccannas .com/
Purchasing Image CD’s
Eyewire product index http://www. eyewire .com/index/