Re: PDF File Size using FM6 and Acrobat 3.05

[Dan Emory <danemory@xxxxxxxxxxxx>]

At 03:42 PM 2/27/01 +1100, Michael Cudmore wrote:
>Dan Emory wrote:
> > on in the Save As dialog. I've found that Distiller-optimized PDF can be
> > reduced in size by as much as an additional 500% by saving with Optimize
> > turned on
> > in Acrobat 4.05.
>
>Well, as reducing the file size by 100% always gives me a zero byte
>file, 500% sounds pretty impressive ...
>
>Cheers,
>
>Michael
>(once upon a time a math and philosophy major, still a pedant)
=========================================
The mathematically rigorous approach to calculating percentage
is based on the premise that percentages express the ratio of a
portion of the whole to the whole (as in polls),  in which
case no value can exceed 100%.

That is:

Let A and B be two numbers, where A is the whole,
and B is a portion of the whole, thus

P = (A - B)/A x 100

Notice that the sign on the percentage value can be misleading
if A and B do not correspond respectively to the whole and a
portion of the whole. For example, if B is greater than A, the
sign of the percentage value is negative, even though it represents
a percentage increase. If B is less than A, the sign is positive,
even though it represents a percentage decrease.
Consequently, if A = 2 and B = 3, the difference is -1, and
the percentage value is - 50%, whereas if A = 3 and B = 2, the
difference (+1) produces the identical percentage value, 50%, but
with a positive sign. Very confusing unless A is always the whole
and B is always smaller because it can only be a portion of the whole.
+++++++++++++++++++++++++++++++++++++++++++++
So,  in cases where you're calculating a percentage difference
between two numbers, neither of which is "the whole," it
seems more fitting to define the ratio as follows:

Let A and B be two numbers, where A is the larger number, thus:

P = (A - B)/B x 100

The percentage value (always having a positive sign) in this case 
represents the
ratio of the difference between the two numbers to the value of the
smaller number. Thus, under this method, percentage values can
range from 0% (if the two numbers are equal) to infinity
(if the smaller number is 0). If  (A  - B) < B the percentage value will
be < 100%. If (A - B) > B the percentage value will be > 100%

Actually, when I claimed a 500% reduction in PDF size was realizable 
(calculated
by the latter approach) I used the wrong numbers. The actual numbers were
a 12 MB file produced by Distiller with Optimize PDF turned on, and a 3 MB file
after the file was re-optimized by means of Acrobat batch optimization, which
corresponds to a 300% reduction in size. This huge reduction occurred because
the bulk of the file content was a highly complex 2-page form that was in the
left/right master pages. The body text flow contained a number of field values
(most relatively short text strings) from database records. These text strings
were overlayed at the proper positions on the 2-page background form
(1000 database records produced a 2000-page file). When Distiller produces
optimized PDF, it fails to recognize that a copy of the background form
doesn't need to be repeated on each page. But, when Acrobat re-optimizes
the same PDF file, it recognizes that only one copy of  the background form
needs to be kept, thus the huge reduction in file size is realized.




====================
| Nullius in Verba |
====================
Dan Emory, Dan Emory & Associates
FrameMaker/FrameMaker+SGML Document Design & Database Publishing
Voice/Fax: 949-722-8971 E-Mail: danemory@primenet.com
177 Riverside Ave., STE F, #1151, Newport Beach, CA 92663
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