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Revision as of 04:50, 28 April 2017 by Raffriff42
Returns a mask (as Y8) of clip using a given hue and saturation range. Added in v2.6.
adds new realcalc parameter.
Syntax and Parameters
MaskHS(clip [, int startHue, int endHue, int maxSat, int minSat, bool coring ] )
- int startHue = 0
- int endHue = 360
- The resulting mask will contain source values in the range [startHue, endHue] when startHue<endHue. Note that the hue is periodic, thus a hue of 360 degrees corresponds with a hue of zero degrees.
- If endHue<startHue then the range [endHue, 360] and [0, startHue] will be selected (thus anti-clockwise). If you need to select a range of [350, 370] for example, you need to specify startHue=370, endHue=350.
- Range 0 to 360 (degrees), default 0, 360; thus when using the default values, all pixels will be processed.
- The following shows some arbitrary startHue and endHue values for the basic colors, with a Histogram vectorscope to illustrate the color circle:
Color startHue (center) endHue Red 075 102 115 Yellow 150 176 180 Green 191 230 258 Cyan 279 282 300 Blue 316 000 004 Magenta 028 048 052
- int maxSat = 150
- int minSat = 0
- The resulting mask will contain source values in the range [minSat, maxSat].
- Practically the saturation of a pixel will be in the range [0,100] (thus 0-100%), since these correspond to valid RGB pixels (100% corresponds to R=255, G=B=0, which has a saturation of 119). An overshoot (up to 150%) is allowed for non-valid RGB pixels (150% corresponds to U=V=255, which has a saturation of sqrt(1272+1272) = 180).
- TODO needs documentation of behavior with Deep Color formats.
- Range 0 to 150 (percent), default 150, 0; thus when using the default values all pixels will be processed.
- bool coring = true
- When set to true, the luma (Y) is clipped to TV-range; when set to false, the luma is left untouched.
- Suppose we want to create a mask of the skin of the girl below. The proper way to do this is to look at the vectorscope of Histogram:
- and estimate the hue range you want to select. As can be seen, the orange hue is between (about) 105 and 165 degrees.
- Note: axis labels have been added to the vectorscope as a guide – they are not generated by the above script
- Start with a wide hue range and narrow it until the output of MaskHS isolates the range of interest. You can also use Tweak to preview the affected range (with sat=0), as the arguments are compatible.
- In our example we end at startHue=105, endHue=138, and the following mask is obtained:
- Looking at the blue screen example in Overlay the following can be used