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hog.detectMultiScale parameters

asked 2013-10-07 13:24:26 -0500

rokasma gravatar image

Hello, Can anyone explaine me in simple words what these parameters:

0, Size(6,6), Size(32,32), 1.05, 2

in this function does?

do hog.detectMultiScale(img, found, 0, Size(6,6), Size(32,32), 1.05, 2);
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answered 2013-10-08 02:41:11 -0500

Siegfried gravatar image

Hi, the HOGDescriptor::detectMultiScale(...) documentation is missing for cpu implementation. But you can take a look at the GPU documentation. From this documentation:

void gpu::HOGDescriptor::detectMultiScale(const GpuMat& img, vector<Rect>& found_locations, double hit_threshold=0, Size win_stride=Size(), Size padding=Size(), double scale0=1.05, int group_threshold=2)


  • img – Source image. See gpu::HOGDescriptor::detect() for type limitations.
  • found_locations – Detected objects boundaries.
  • hit_threshold – Threshold for the distance between features and SVM classifying plane. See gpu::HOGDescriptor::detect() for details.
  • win_stride – Window stride. It must be a multiple of block stride.
  • padding – Mock parameter to keep the CPU interface compatibility. It must be (0,0).
  • scale0 – Coefficient of the detection window increase.
  • group_threshold – Coefficient to regulate the similarity threshold. When detected, some objects can be covered by many rectangles. 0 means not to perform grouping. See groupRectangles() .

I recommend you to read the original HoG paper [Navneet Dalal and Bill Triggs. Histogram of oriented gradients for human detection. 2005]. In this paper the authors explain all parameters in detail and show how different parameter settings influence the detection rate.

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Asked: 2013-10-07 13:24:26 -0500

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Last updated: Oct 08 '13