Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
What do you mean by filtering? What do you expect for the result? If you are trying to read text, you need OCR tools. If you are trying to recover text covered by black, I doubt that is possible. Please clarify your request.
Please always provide your IM version and platform when asking questions as syntax may vary.