Welcome !

Welcome to Filter Central ! Here you'll find resources, examples and discussions pertaining to the IFilter COM interface, the de facto standard for creating document filters to work with Windows Indexing service, Windows Desktop Search and Microsoft Sharepoint technologies.

The interface is defined in MSDN as follows:

"The IFilter interface scans documents for text and properties (also called attributes). It extracts chunks of text from these documents, filtering out embedded formatting and retaining information about the position of the text. It also extracts chunks of values,which are properties of an entire document or of well-defined parts of a document. IFilter provides the foundation for building higher-level applications such as document indexers and application-independent viewers."

The primary objective of this forum is to provide a platform for discussing various implementation and deployment issues pertaining to components that implement the IFilter interface (both Microsoft and third party) in the context of Windows XP, Win2K server,Windows desktop search ,and Microsoft Sharepoint technologies.

I encourage all consumers and implementors of document filter to actively paticipate in this forum by discusiing problems and solutions to Filter implementation, debugging and deployment in microsoft software environments. Happy Filtering !!!


Disclaimer: The views and opinions expressed in this forum are solely that of the creator and participants  and are not endorsed by Microsoft in any way whatsoever.

Comments (7)

  1. michkap says:

    Looking forward to conversations about the use of IFilter (especially since I have not been able to answer all the questions that people have asked me over the last few years!).

  2. In the same boat as Michael… Lots of good questions from the folks who visit my site.  I don’t have all the answers either.

  3. (About 2-5 times a week, I think of a pun that I go down the hall and mention to Judy and Carolyn on

  4. Dima says:

    Good to see you, man. I have no idea what IFilter means, but it sounds cool 😉

  5. Malek Badi says:

    I had thoughts regarding an improved approach for document filtering .. Pls see my blog at:


  6. Deb Haldar says:

    This is a novel concept which Microsoft research has been working on for the last couple of years.

    In the current version of Enterprise Search, we have several mechanisms in place that does extract revelance information from document formatting (Bold, Italics, Underline, Font, Color etc) and use them actively in ranking of the search results.

    These features are deployed as active plugins in the search gathering pipeline and process the formatting information emitted by filters.

    This is typically achieved by passing the EMIT_FORMATTING flag to IFilter::Init() method which forces the filter to emit various relevant formatting information which are used by plugins such as Title Extraction, Definition Extraction, Did You Mean etc to rank and categorize the inverted index of search results.

  7. 話題の小向美奈子ストリップを隠し撮り!入念なボディチェックをすり抜けて超小型カメラで撮影した神動画がアップ中!期間限定配信の衝撃的映像を見逃すな

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