[Paddlewise] Copying legally.

>Date: Thu, 14 May 1998 19:38:27 -0400
>From: Rich Kulawiec <rsk_at_gsp.org>
>Subject: Re: [Paddlewise] FW: Copying legally . . .
>
>On Thu, May 14, 1998 at 06:07:06PM +0000, R. Walker wrote:
>> > Do you have any idea how big a file a scanned two-foot by three-foot
>> > chart would require at 300 dpi? A quick calculation shows that to be
>> > 77,760,000 pixels!
>>
>> Which is why USGS has their topos distributed on CDROM, not the
>> web.  Maybe a day will come when the internet can push a 77 meg
>> file for individual use, but we are a ways away from that.
>
>As I've already pointed out, such files compress quite nicely -- and using
>standard, publicly-available compression filters.  There's no need
>to push 77 Mbyte files around.  The web *is* the appropriate means by
>which to distribute these, especially since web technology can be
>used to produce custom topos which include/exclude specific kinds of
>features -- expanding and shrinking the size of the resulting data
>files based on user preferences.
>
>Here, play with this as an example:
>
>http://pubweb.parc.xerox.com/map/color=1/db=usa/features=alltypes/ht=0.68/lat=4
>0.38/lon=-105.59/wd=1.36?227,169
>
>It's Rocky Mountain National Park as seen by such a prototype-grade
>implementation of just such an interface.
>
>- ---Rsk
>Rich Kulawiec
>rsk_at_gsp.org
>
>------------------------------

There is a big difference between a 300 Mb text file and a 300 Mb graphics
file.
With graphics the rule is the higher the compression the low quality of the
resulting image(JPEG).

file size for a 24 x 36 inch chart:
72 pixel per inch (ppi) RGB screen resolution = 12.8 Mb
120 ppi RGB low resolution to print on laser/ ink jet print at 60 Line per
in. 35.6 Mb
200 ppi RGB resolution to print on laser/ ink jet print at 100 Line per in.
=98.9 Mb
266 ppi CMYK file for lithographic reproduction 4 colour printing = 233.2 Mb

Even if this images were jpeged the file size for a printable file would
still take a  hour plus to download.

The map images found on the xerox site are very low resolution and would be
impossible to navigate by.

If I was navigating by these charts I would like them to be as high of
quality as possible.
also how many of us have printers capable of printing a 24 x 36 in. colour
chart.
The price to have this output at a commercial imaging centre would be more
then the cost of the original chart.

Bill Silver







***************************************************************************
PaddleWise Paddling Mailing List
Submissions:     paddlewise_at_lists.intelenet.net
Subscriptions:   paddlewise-request_at_lists.intelenet.net
Website:         http://www.gasp-seakayak.net/paddlewise/
***************************************************************************