Well, trying not to be anal about it, bu technically, resolution in
pixels normally refers to digital converted to analog computer screen
capabilities.  DPI, or dots per inch, usually refer to scanners or
printer capabilities.  Pixels refer to full screen usage.  For example,
1024x768 resolution will be 1,024  (dots across) times 768 pixels (dots
down) = 786,432 elements of information, regardless whether the screen
is 3 inches or 36 inches.  The picture remains the same and the total
size of the image stays the same.

Now, dpi is not like that at all.  100 dpi (squared is the norm, that is
y dots across by y dots down).  Therefore, at 100 dpi a 3x5 scanned
picture will yield 3x100 times 5x100 = 150,000 elements of information.
Ignore color depth for the moment.  At the same 100 dpi, an 8 1/2 x 11
inch picture scanned will require 8 1/2*100 * 11*100, or 935,000 pieces
of information.  Ok, if you now assume 24 bit color, multiply each
number by 3 (8 bits per byte) to get the actual uncompressed size of the
files.  3x5 at 100 dpi in true color = 450,000 bytes.  8 1/2 x 11 in
true color = 2,805,000 bytes.  Finally, an 8 1/2 x 11 image scanned and
saved in 300 bpi yields a file size of 25,245,000 bytes or 25 megabytes
roughly!  Imagine sending that one page over someone's telephone
Internet connection.  Shoot, even DSL or cable modem will choke a little
on each page at that size.

That is why the larger scanned images take so much more space to send
via email.

HTH (and you didn't get too bored),
AI Nut

You missed one thing. A jpg will compress this a lot.

You do have a very important point however.
It started with the Macintosh and went down hill from there.
Somebody decided it would be cute if they allowed bit mapped
fonts in word processors and other programs. This causes
Microshit Word for example to convert a 14K plain ASCII text file
and a few jpg's totaling about 350K into a .doc file over 20Meg!
The bit mapped fonts add absolutely nothing to the information
contained in the plain ASCII text file. All it does is line the pockets
of digital terrorist Bill "Osuma bin Laden" Gates with riches
way beyond anybody's wildest imagination.
This set world wide computer productivity back 20 years!

Ed Anderson just tried to send me that 20 meg file broken up in to
several multi megabyte pieces and it brought the mighty
earthlink.net to its knees. Not your fault Ed. How could you
have known? I had to call earthlink and have them abort the
process.

That bit mapped

Gee, Paul, sorry 'bout that.

    I am surprised because when my server indicated it aborted the earlier
transmission due to my 20 Meg message exceeding its size limitation.   I
then split the article into a number of pages, but one was around 5 Meg as
best I recall, so I guess even breaking it up into smaller chunks can still
bogg a server if received over a short period of time.  Perhaps if I had
streached the transmission out over 30 minutes or an hour, it would not have
clogged the server.

    The basic problem stems from me imbedding high Resolution images in the
text.  Several publishers indicated they needed print quality (300 pixel)
resolution and that is what many of the photos were.  However, for the
internet, I will in the future reduce the photos to 100 pixels and save a
lot of space and reduce the aggravation to you, Paul.

Ed Anderson

 
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