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2013-05-09T15:01:59Z

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{{FilterCat|External_filters|Other_filters|Support_filters}}

{{Func2Def|DEdgeMask (clip[, int "thY1"[, int "thY2"[, int "thC1"[, int "thC2"[, string "matrix"[, float "divisor"[, bool "setdivisor"[, bool "vmode"]]]]]]]])
|DEdgeMask2 (clip source, clip low_thres, clip high_thres[, string "matrix"[, float "divisor"[, bool "setdivisor"[, bool "vmode"]]]])}}

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

'''DEdgeMask''' creates an edge mask of the picture. The edge-finding algorithm uses a convolution kernel, and the result of the convolution is then thresholded with <tt>thY1</tt> and <tt>thY2</tt> (luma) and <tt>thC1</tt> and <tt>thC2</tt> (chroma). The thresholding happens like that (r is the result of the convolution):

* r <= th1 gives 0.
* th1 < r <= th2 gives r.
* th2 < r gives 255.

In order to create a binary mask, you just have to set th1=th2.

The choice of the convolution kernel is done with <tt>matrix</tt>. The <tt>matrix</tt> must be a 3 by 3 matrix, whose coefficients are integers, separated by a single space. Hence, the strings "-1 -1 -1 -1 8 -1 -1 -1 -1" and "0 -1 0 -1 0 1 0 1 0" will respectively give the kernels "laplace" and "sobel" of the filter [[MaskTools/EdgeMask|EdgeMask]].

As coefficients must be integers, <tt>divisor</tt> is used to refine the result of the convolution. This result will simply be divided by <tt>divisor</tt>. If <tt>divisor</tt> isn't defined, it is defaulted to the sum of the positive coefficients of the matrix, thus allowing a classic normalization. It can be either a float or an integer, the later being the faster.

<tt>setdivisor</tt> is present only for backward compatibility. Do not use it.

Finally <tt>vmode</tt> allows to output a mask centered to 128 instead of zero.

Defaults are:
* <tt>thY1</tt> = 0, <tt>thY2</tt> = 20,
* <tt>thC1</tt> = 0, <tt>thC2</tt> = 20,
* <tt>matrix</tt> = "-1 -1 -1 -1 8 -1 -1 -1 -1"
* <tt>vmode</tt> = false.

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'''DEdgeMask2''' basically works like DEdgeMask, except that instead of 2 low / high thresholds, it takes 2 other clips. Each clip contains local thresholds for each pixel.

Let's say you want adaptive thresholds taking local contrast into account. Well, local min & max can be obtained through [[MaskTools/Inpand|inpand()]] and [[MaskTools/Expand|expand()]]. Difference can be made with [[MaskTools/YV12LUTxy|YV12LUTxy]] or [[MaskTools/YV12Subtract|YV12Subtract]]. And voilΰ, you've got a threshold clip containing local contrasts.

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Back to [[MaskTools]].

MaskTools/DEdgeMask - Revision history

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