Question about Embedded Image Filter |
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lyndonje 
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Joined: 31 January 2006 Location: United Kingdom Status: Offline Points: 192 |
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 Topic: Question about Embedded Image FilterPosted: 03 May 2006 at 9:54am |
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Hi,
I have a question about the Embedded Image Filter, I was just wondering how it worked? (Just in basic terms). How does it determine what is likely to be spam? The reason I ask is the below image (which was set as a email's background) was blocked. Thanks.  |
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mikek
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Joined: 22 February 2005 Location: Switzerland Status: Offline Points: 133 |
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Posted: 03 May 2006 at 9:58am |
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I wanted to ask the same question some time ago as well...
I saw a very interesting plugin for Spamassasin, which does the detection based on ocr... maybe this could be a way to go? see source here: http://mx.imp.ch/patches/patch-ocrtext |
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LogSat
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Joined: 25 January 2005 Location: United States Status: Offline Points: 4106 |
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Posted: 03 May 2006 at 3:46pm |
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Unfortuantely we prefer not to go in details on how the image filter works so as not to provide clues to spammers. I can only suggest tweaking the threshold value for the filter to reduce the aggressiveness if too many false positives are detected.
Sorry! |
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lyndonje
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Posted: 04 May 2006 at 3:44am |
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I understand your reasoning, but how none agressive does it have to be
for it not to pickup a fairly haizy picture of clouds containing no
characters, but still detect spam?
Instead of SF users having to use pure guess work & trial and error, could you give us some examples of the type of images that would and would not be detected at different thresholds? And also explain what the likely effects will be of changing the colorsensitivity setting and number of sampling points? Then we are at least making educated guesses and have an idea of what effects tweaking these settings are likely to make? Thanks. Edited by lyndonje |
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kspare
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Joined: 26 January 2005 Location: Canada Status: Offline Points: 334 |
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Posted: 04 May 2006 at 3:59pm |
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Perhaps there should be a member section on the forum for verified buyers that are not spammer so as to reveal things like this?
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LogSat
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Posted: 04 May 2006 at 4:16pm |
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lyndon, kspare,
We'd again prefer not to give out too much information, even on a member-only section. Google's arms are worse than a giant octopus, they reach everywhere... If you contact us by email we'll try to have a better answer with more details, if you can please assure us you will not divulge the information. |
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lyndonje
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Posted: 05 May 2006 at 5:30am |
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Thats fair enough. Thanks.
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sgeorge
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Posted: 02 August 2006 at 11:37am |
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Interesting... I just turned on the image filter last week and today, I noticed a false positive image-scan from an email including with the same bg cloud image as you, lyndonje. Just thought I'd mention it. I can live with a few false positives - this filter is still very usefull.
Stephen |
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MartinC
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Joined: 29 July 2005 Status: Offline Points: 25 |
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Posted: 05 September 2006 at 10:02am |
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bump... interesting. we've had exactly the same thing happen. and the same image. I like the image filter .. looks very promising but really need to have an idea what it is trying to block, or what happens with the different levels from 0 (disabled) to ... 99 is it? 10 seems to be the default and is what this was blocked at. user looks like they used Outlook but with Word as the editor if its any help. |
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LogSat
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Posted: 05 September 2006 at 9:43pm |
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The threashold goes from 0 to 255, and it's a variable we use for statistical analysis of the image. There's no set rule on what the best value is. The higher the threshold, the more aggressive the filter. Unfortunately statistics is not an exact science, so this is a setting that, if tweaked, will require trial and error to see what setting is most appropriate for your install.
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MartinC
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Posted: 06 September 2006 at 4:28am |
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so everyone getting the fairly standard outlook blue stationary being blocked at 10? thats not very useful to be honest, especially if there could be more. I know it is blocking other things correctly but just wonder at the level of false positives. |
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LogSat
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Posted: 06 September 2006 at 4:17pm |
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MartinC,
Please email us at support at logsat dot com, we may have a tool that could help you understand better the settings. |
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jemmie
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Posted: 09 September 2006 at 8:31am |
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I can't change my threashold any higher than 15. Even when I try to change the value whithin te spamfilter.ini it won't show in the gui jemmie Edited by jemmie |
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LogSat
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Posted: 09 September 2006 at 11:26pm |
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Yes, you're correct, I'm sorry. We're limiting the threshold to 15 in the GUI, as higher values would stop too much legitimate emails.
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