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From: Thom Brown <thombrown@gmail.com>
Date: Sat, 3 Jul 2010 23:48:25 +0100
Message-ID: <AANLkTikNVB8sKyV3WDU74JqSYzQUwbaPz87Qh2FfVlqu@mail.gmail.com>
Subject: Re: Documentation and explanatory diagrams
To: Bruce Momjian <bruce@momjian.us>
Cc: Peter Eisentraut <peter_e@gmx.net>, Tom Lane <tgl@sss.pgh.pa.us>,
	Alvaro Herrera <alvherre@commandprompt.com>,
	Rafael Martinez <r.m.guerrero@usit.uio.no>,
	pgsql-docs <pgsql-docs@postgresql.org>, Marc Fournier <scrappy@hub.org>
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On 3 July 2010 13:59, Thom Brown <thombrown@gmail.com> wrote:
> On 3 July 2010 03:41, Bruce Momjian <bruce@momjian.us> wrote:
>> Peter Eisentraut wrote:
>>> On fre, 2010-07-02 at 22:15 -0400, Bruce Momjian wrote:
>>> > > 500k of source for just half a dozen simple images? =A0There's
>>> > something
>>> > > seriously wrong there. =A0I suspect the PNGs could be compressed a =
lot
>>> > > more, but right now I'm wondering exactly how verbose the dia
>>> > "source"
>>> > > representation is.
>>> >
>>> > Here is the PNG URL:
>>> >
>>> > =A0 =A0 =A0 =A0 http://momjian.us/expire/pgsql-docs/img/
>>> >
>>> > and the dia files:
>>> >
>>> > =A0 =A0 =A0 =A0 http://momjian.us/expire/pgsql-docs/dia/
>>>
>>> The dia stuff is XML that should compress well.
>>
>> Gzip takes the dia directory from 526k to 42k. =A0And of course gzip doe=
s
>> little for the PNG files.
>>
>
> How configurable is the generation process for these PNGs? =A0It's just
> that they don't appear to be optimised.
>
> For example, pgclient_server.png is created at 75,089 bytes, but can
> be reduced to 15,643 bytes like in the attached file
> (pgclient_server2.png) by using a 16-colour indexed palette.
>
> Thom
>

Being a bit more generous, and using a 32-colour palette, it looks
like it yields a typical saving of 75%

Original images:

40290	file_based_log_shipping.png
54211	hot_standby.png
52400	page_layout.png
75089	pgclient_server.png
49117	pg_dir_layout.png
17692	pg_lines_code.png
41723	pg_standby.png
25135	pitr.png
10946	postgresql_hist.png
34156	streaming_replication.png
68679	tablespaces.png
18197	vacuum.png

TOTAL: 487635 bytes

32-colour palette images (compression %):

10700	file_based_log_shipping2.png (73.44%)
14245	hot_standby2.png (73.72%)
9896 	page_layout2.png (81.11%)
13786	pg_dir_layout2.png (81.64%)
6347 	pg_lines_code2.png (87.08%)
11211	pg_standby2.png (36.63%)
18173	pgclient_server2.png (56.44%)
7148 	pitr2.png (71.56%)
3873 	postgresql_hist2.png (64.62%)
8969 	streaming_replication2.png (73.74%)
15338	tablespaces2.png (77.67%)
5846 	vacuum2.png (67.87%)

TOTAL: 125532 bytes (74.26%)

..just an idea anyway.

Thom