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- Newsgroups: sci.image.processing
- Path: sparky!uunet!math.fu-berlin.de!irz201.inf.tu-dresden.de!ti1
- From: ti1@irz201.inf.tu-dresden.de (Torsten Ihle)
- Subject: Re: Help Wanted: Contour Tracing
- Message-ID: <SK1007N@math.fu-berlin.de>
- Sender: news@math.fu-berlin.de (Math Department)
- Reply-To: ti1@irz201.inf.tu-dresden.de (Torsten Ihle)
- Organization: Free University of Berlin, Germany
- References: <1993Jan21.192619.10241@pinet.aip.org>
- Date: Fri, 22 Jan 1993 09:27:29 GMT
- Lines: 33
-
-
- --
- In article <1993Jan21.192619.10241@pinet.aip.org>, scotj@pinet.aip.org (scot_shinderman) writes:
- [...]
- |> While reading the standard image processing books I have noticed one
- |>algorithm that seems to be glossed over: contour tracing. In the
- |>pictures that I am scanning, a filter is run across the pixels and a
- |>threshold is applied to produce either white or black pixels for the
- |>grey-scale. At this point there is usually a rather disconnected set of
- |>dots due to noise in the picture but also some strong edges from the
- |>filter. What is the "pratical" method of moveing along the detected
- |>pixels to find lines (or curves). If I try to step from one pixel to
- |>the next by looking in a neighborhood, then the path almost always gets
- |>caught up in the noise off to one side or another. Is there a way to
- |>"nudge" the search in a particular direction based on previous motions.
- [...]
-
- 1) You can try to fix some "small gaps" in your lines by morphological
- operations ( n times dilate and afterwards n times erode, where 0<n<6 ).
- 2) You can use a Hough-Transform to get clues, where to find lines (or curves)
- in the image.
- 3) You can use a sort of relaxation method to extract the lines, but to do
- this you can not simply threshold your filter output.
- 4) You can extract line parts as a symbolic description of the connected
- components of your binary image and join line parts to lines (or curves)
- by symbolic methods
-
- ----------------------------------------------
- Torsten Ihle, cand. inf., TU-Dresden
- EMail: ihle@iki101.inf.tu-dresden.de
-
- Es ist deutsch in Kaltland !
- ----------------------------------------------
-