message: Clarify docs for MOG2::apply
diff: @@ -195,6 +195,17 @@ public:
  /** @brief Sets the shadow threshold
  */
  CV_WRAP virtual void setShadowThreshold(double threshold) = 0;
  +
  + /** @brief Computes a foreground mask.
  +
  + @param image Next video frame. Floating point frame will be used without scaling and should be in range \f$[0,255]\f$.
  + @param fgmask The output foreground mask as an 8-bit binary image.
  + @param learningRate The value between 0 and 1 that indicates how fast the background model is
  + learnt. Negative parameter value makes the algorithm to use some automatically chosen learning
  + rate. 0 means that the background model is not updated at all, 1 means that the background model
  + is completely reinitialized from the last frame.
  + */
  + CV_WRAP virtual void apply(InputArray image, OutputArray fgmask, double learningRate=-1) = 0;
  };
  /** @brief Creates MOG2 Background Subtractor
  