Jules Verne Forum

<jvf@Gilead.org.il>

JanFebMarAprMayJunJulAugSepOctNovDec 19961997199819992000200120022003200420052006200720082009

Re: The Verne Virtual Voyages Atlas Project?

From: James D. Keeline <james~at~keeline.com>
Date: Fri, 13 Jul 2001 23:51:40 -0700
To: Jules Verne Forum <jvf~at~math.technion.ac.il>

>From a standpoint of printing, GIF images, using 2-bit or 4-bit color depth
would be not only sharper but the files should be very small. If you take
an existing JPG and then save it as a GIF, you won't see a difference because
the edges can be grey to handle the anti-aliasing. This will be the greatest
issue when dealing with small details.

PNG is a relatively new format but the browsers from the past two years or so
will display them. GIF was developed by CompuServe in the 1980s and it uses
a compression scheme owned by Unisys. A couple of years ago, Unisys was trying
to enforce its patent. However, companies like Adobe and Macromedia have paid
their royalties to Unisys so one can generate GIF files without problems. PNG
stands for "Portable Network Graphics", I believe, and it is an open source
standard. It is the native file format for Macromedia Fireworks. I don't
think that PNGs can be animated as GIF 89A files can though that doesn't apply
for our project.

If you have a GIF file saved at 150 dpi which is 300 x 300 pixels, when it is
displayed on a web page, it will appear at the same size as a 300 x 300 pixel
image saved at 72 or 75 dpi. The difference comes when you bring it into a
graphics program for printing. The program notes the resolution and keeps the
dimensions appropriate for printing purposes.

It would be a good idea to have thumbnails of the images. It is even possible
to have a PHP program (open source web programming language which typically
runs on Linux with Apache) which will generate thumbnails on the fly to be
displayed. However, if one starts out with a 300 or 600 dpi GIF of the maps
and then creates a thumbnail image at 75 dpi perhaps at 50% of the original
size, you can get the results you are trying to achieve.

Obviously, we have 600-650 MB to play with on a CD-R; stay away from the 700
MB discs since they are often incompatable with many readers. The key is to
figure out how many pictures you want to display and then determine the best
resolution to fit. I suspect it will be 300 dpi.

An Adobe Acrobat file may not be necessary and can be counterproductive in
some cases. You could make some web pages to access the GIFs (or JPG files
if you insist) which is similar to the web access but much faster for those
who don't have high-speed connections.

James D. Keeline
editor of the NAJVS newsletter, EXTRAORDINARY VOYAGES
Received on Sat 14 Jul 2001 - 09:52:09 IDT

JV.Gilead.org.il
Copyright © Zvi Har’El
$Date: 2009/02/01 22:36:11 $$