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HOWTO: Preparing Graphics Files for a Presentation
Jefferson H.S. Technology Committee. v1.0
By K. Ballash

Generally when you take a digital photo or scan a drawing your intention is to use them in a word processing report, a StarOffice or Power Point presenation, or student portfolio or web page. Graphics are rarely presented simply with graphics software. They are part of another document, providing evidence, examples, or enhancement and accompanied by written descriptions, commentary or explantations. Often the primary written document is already in the planning stages and the author searches for a specific photo or illustration to provide a specific example of a concept in the essay or report. The author might take the digital photo or create the illustration himself, or use other graphics with permission. This tutorial focuses on preparing graphics for those presentation documents such as a web page created with Netscape Composer.

There are many image editing programs ranging from the very expensive Adobe Photoshop to the software that is normally included with scanners and digital cameras. Often Photoshop Light ($95 when sold separately), for example, is often bundled with scanners. Programs like Paint Shop and Photo Suite are only $30 to $40. Graphic Converter is a popular graphics program (shareware, $35) for the Mac OS. Gimp is a powerful but complicated open source, freeware replacement for Photoshop for the Windows and Linux OS. MS Paint which is included in Windows offers some basic drawing and graphics tools. This tutorial will use the free, open source StarOffice for Windows and Linux OS. This replacement for MS Office offers a bit more then the basic features in its graphics editor package. The main features that you want are the ability to crop, change resolution, change file format, change display size, flip and rotate.

Use JPEG and GIF and PNG formats. Use jpeg for photos, either scanned or from digital cameras. Use gif and png formats for diagrams, line drawings and graphs.

Use "Save as..." at beginning to experiment with file and not change original. Try out a new filter or other modification without altering the original file.

Manage graphics file sizes. Shoot for no more then one to three graphics per page, 30-40kb each, 2.5 to 4 inches wide at most.
Especially for web pages, when the graphics files get too large, the pages load slowly. See other tutorials: scanning, photos, free lessons, vendor help sites.

Vocabulary: pixel, kb, crop, resolution, file format, html, RGB, JPEG, GIF, PNG, TIFF, greyscale,

Examples of  tools available in StarOffice's image editor
 

Croping

Select
then Modify>Crop>Save as...

 250w x 283h before croping 235w x 135h after

 
Change size
and reduce KBs

Modify>Modify size...
Type in number of pixels
for new size. Remember 
72 pixels equals 
one inch. The width was
reduced from 250 to
125 pixels. File size was 
reduced from 207 KB
to 51 KB.
 

 File size is 207 KB before reduction File size reduced 75% to 51KB

 
Filters
charcoal filter Relief filter Poster filter
Charcoal Relief Poster
Pop Art filter Solarization filter Charcoal and solarizing filter combined
Pop Art Solarize at 25% Charcoal + Solarize
Mosaic filter Tile filter Aging-adds a reddish color
Mosaic Tile Aging

 
 
Colors-RGB Colors
80% Red 80% Green 80% Blue
Colors>RGB colors... Red 80% Colors>RGB colors... Green 80% Colors>RGB colors... Blue 80%

 
Colors-II
Greyscale, 128 black and white Invert
Convert to Greyscale (128 black and white) Invert

David image downloaded from the
Stanford Computer Graphics Laboratory, The Digital Michelangelo Project. September 2, 2001. http://graphics.stanford.edu/projects/mich/color-david/fd35bigh-cbal-e.jpg

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Computer graphic by K. Ballash. All other graphics downloaded from Anthony's Icon Library,WWW Images: http://www.cit.gu.edu.au/images/Images.html , December,  1998.