View source for MaskTools/MotionMask

{{FilterCat|External_filters|Other_filters|Support_filters}}

{{FuncDef|MotionMask (clip[, int "thY1"[, int "thY2"[, int "thC1"[, int "thC2"[, int "thSD"]]]]])}}

'''Plugin''': [[MaskTools]]

This filter creates a mask of the motion of the picture. As with the other filters which create masks, once the motion is computed, it is thresholded by two thresholds. This filter will also check for scene changes, and won't output a mask if a scene change is detected.

Scene change detection is made by computing the sum of absolute differences of the picture and the previous one. This sum is averaged, and then compared to <tt>thSD</tt>. If it is more than <tt>thSD</tt>, a scene change is detected.

Motion is computed the same way as [[NoMoSmooth]], meaning that for each pixel, we'll compute the absolute sum of differences between the pixel and its surrounding, and the pixel and its surrounding in the previous picture. The resulting value is then divided by 9, in order to normalize the result between 0 and 255.

This algorithm only gives an approximation of the motion. It will work well on the edges of an object, but not on its inside.

Defaults are : <tt>thY1</tt>=20, <tt>thY2</tt>=20, <tt>thC1</tt>=10, <tt>thC2</tt>=10 and <tt>thSD</tt>=10. 

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