Motion - Config Option Despeckle

despeckle

  • Type: String
  • Range / Valid values: EedDl
  • Default: Not defined
  • Group: Image Processing

Despeckle motion image using combinations of (E/e)rode or (D/d)ilate. And ending with optional (l)abeling., Despeckle motion image using combinations of (E/e)rode or (D/d)ilate. And ending with optional (l)abeling.

A way of tuning (by removing or enhancing) noise in the motion image. Options for the despeckle feature are any of 'e', 'E', 'd' or 'D'. This can be combined by a trailing 'l' (letter l) which enables the labeling feature. Default: Not Defined (Don't despeckle and label).

Wind blowing grass and trees around or poor light conditions can cause a lot of dots (or noise) to appear in the motion image (See the section on Tuning Motion). This feature removes (or enhances!) this noise and so improves the reliability of motion.

The 'e' option removes diamonds, 'E' removes squares and alternating eE will remove circles. Each e/E you add will shrink the noise by a pixel all the way around. So 'despeckle Ee' will remove circles of radius 2. However, this will also shrink the detection by 2 and will affect the threshold. So to remove noise and then restore the detected motion to its original size try 'despeckle EedD'.

After the despeckle feature is done you can let the labeling feature search for areas of connected pixels and "label" each area. The program will now trigger motion based on the number of changed pixels in the largest area. In other words, the largest labeled area has to be above the threshold to trigger a motion detected.

The value EedDl is a good starting point. The possible combinations are endless and it requires many experiments to find the best combination. Just remember that the labeling feature only works as intended if it runs after the despeckle feature. Ie. the letter 'l' must be the last letter and only one 'l'.

If you have very few problems with false detections leave this option either blank or at EedD which will remove most of the single pixel noise. A very detailed technical explanation of the despeckle part can be found at the webpage of the author of this feature Ian McConnell's Webcam: Motion Web Page
Topic revision: r9 - 07 Aug 2016, KennethLavrsen
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