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Installation manual for FuzzyOcr 2.3:
1. Dependencies you require for this plugin to work
Before starting, also make sure to read the OS/distribution specific notes at the end of this section.
1.1 Spamassassin 3.x
This plugin requires Spamassassin 3.x. Using it on version 2.x is not supported and might fail.
At least one function in this plugin requires Spamassassin 3.1.4, if you do not have this version,
don't forget to set the "focr_pre314" option in the FuzzyOcr.cf file.
1.2 NetPBM tools
Install the NetPBM tools (http://netpbm.sourceforge.net/). If you don't install the binaries in /usr/bin,
please make sure to adjust the FuzzyOcr.cf to point to the correct binaries.
1.3 ImageMagick
At least one feature requires the convert binary from imagemagick (http://www.imagemagick.org/).
Again, make sure the configuration file points to the convert binary, if not placed in /usr/bin.
1.4 Giflib (also known as libungif)
Several tools from this package are required, see (http://sourceforge.net/projects/libungif).
Attention: the giftext binary from this package has a bug which can cause segfaults.
On the download page, a source patch is provided which fixes this.
1.5 Gocr
For OCR recognition, gocr (http://jocr.sourceforge.net/) must be installed.
Attention: the gocr binary has a bug which can cause segfaults with specific images.
On the download page, a source patch is provided which fixes this.
1.6 Perl modules:
These perl modules are required:
Digest::MD5
String::Approx
Notes for Fedora Core 5 (or higher) users: The package libungif-utils provides the necessary libungif binaries.
Notes for other Redhat/FC users: The packages libungif and libungif-progs should be installed.
Notes for Debian users: The package libungif-bin provides the necessary libungif binaries.
Notes for Slackware users: I have no clue about this distro, but Andy Lyttle sent me a mail about it:
"Slackware doesn't currently have a libungif-utils/progs/bin package, and the libungif package does not include the binaries such as giffix. So, you have to hack it a bit.
1. Download (or copy from CD) the /source/l/libungif directory, don't untar anything
2. Edit the libungif.SlackBuild and comment out this line:
# I don't believe we need all this slop. Correct me if I'm wrong.
rm -rf $PKG/usr/bin
3. Run "sh libungif.SlackBuild"
4. Uninstall the libungif package, if it's already installed
5. Look in /tmp, and install the new libungif package there"
Notes for Gentoo users: All dependencies except the perl modules can be installed via portage. But because of the bugs in giftext and gocr,
you might need to write an ebuild which uses the two patches found on my download page. The perl modules can easily be
installed with gcpan.
2. Installing the plugin:
2.1. Installing the required files
Put the FuzzyOcr.cf and the FuzzyOcr.pm files into /etc/mail/spamassassin.
The FuzzyOcr.cf file already contains a line to load the plugin, if you want to put the .pm file in a different location,
change this line accordingly.
Create a wordlist file, a sample wordlist is shipped with this release, and put it also in /etc/mail/spamassassin.
2.2 Necessary configuration
Open the FuzzyOcr.cf. Make sure that you specify a writable file as a logfile, or a directory where the plugin can write to,
so it can create the logfile itself. Also make sure that you specify a correct file as global wordlist.
With these two adjustments, FuzzyOcr is already to work.
3. Further adjustments
3.1. Enabling the image hash database
Set focr_enable_image_hashing to 1 in the config file, and make sure that focr_digest_db points to a writable file/directory.
You can also create this file yourself if you like. By default, all images recognized as spam, are added
to this database automatically. The score is saved as well and reused later again.
3.2 Tweaking Scansets
Everyone gets different image spam, and most times, one method to scan is not successful with all types of spam you get.
That's where the focr_scansets setting can help you. This setting takes a comma seperated list of scansets.
Each scanset starts with the name of a program, followed by either other programs connected with pipes, or nothing anymore.
The only important thing is that input for this "program chain" is a picture in the PNM format, and the output is ASCII text.
An example might clarify this:
focr_scanset gocr -i -
This will do a single scan with gocr default settings.
focr_scanset pnminvert | gocr -i -
This will use pnminvert on the image and then do the scan.
focr_scanset gocr -i -, gocr -l 180 -i -
This will do 2 scans, one with the default settings, and the second one with a modified -l value.
You are now free to select which scansets get you the most spam, but don't pick too many, as this will also use more resources.
Here are some hints: -pnminvert or pnmquant are useful with white text or text with many colors
-If you get images which are littered with small dots/lines, try -d 2 as an argument to gocr
-The -l setting often helps, try values like 180, 140, or 100
Two syntax remarks: -Instead of writing "gocr", write "$gocr" as this will be replaced with the correct path to your gocr binary.
-If you invoke custom binaries (like pnminvert for example), you can redirect the stderr output by using:
"pnminvert 2>>$errfile"
If the scanset fails then, and debug logging is enabled, you will see this stderr output in the logfile :)
I know this seems confusing for some, but if this is unclear somehow, feel free to write an email to the list.
And now, where it gets most thrilling...
To be continued...
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