![Page 1: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/1.jpg)
Histograms of Oriented Gradients for Human Detection(HOG)
Presenter :JIA-HONG,DONG
Advisor : Yen- Ting, Chen
1
Dalal, N.; Triggs, B., IEEE Computer Society Conference on Computer Vision and Pattern Recognition(2005) vol. 1 ,pp.886 - 893
![Page 2: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/2.jpg)
Outline1. Introduction2. Methodology3. Results4. Discussion 5. Conclusion
2
![Page 3: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/3.jpg)
Introduction Detecting humans in images is a
challenging task Variable appearance Wide range of poses
A robust feature set Discriminate cleanly
Cluttered backgrounds Different illumination
3
![Page 4: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/4.jpg)
Introduction Edge orientation histograms
Scale-invariant feature transform (SIFT) Shape context
4
Shape contextSIFT
![Page 5: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/5.jpg)
Introduction Using linear SVM as a baseline classifier Using detection error tradeoff (DET) Data Sets
MIT pedestrian set INRIA pedestrian set
5
![Page 6: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/6.jpg)
Methodology Data Sets
MIT pedestrian database 509 training images 200 test images
INRIA 1805 64X128 images
6
![Page 7: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/7.jpg)
Methodology
7
1 2 3 4 5
6 7 8 9 10
![Page 8: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/8.jpg)
Methodology Training examples 12180+ examples
2478 Positive 1218 Negative
8
![Page 9: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/9.jpg)
Methodology Detection error tradeoff
X-axes False Positives Per Window tested(by 5% at 10-4) FPPW=
Y-axes Miss rate=
Log-log scale
9
![Page 10: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/10.jpg)
Methodology
10
![Page 11: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/11.jpg)
Gamma/Color Normalization Inputting pixel representations
Grayscale RGB color spaces LAB color spaces
Power law (Gamma equalization)
11
![Page 12: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/12.jpg)
LAB Color Spaces
12
Xn, Yn and Zn are the CIE XYZ tristimulus values of the reference white point
![Page 13: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/13.jpg)
Power Law (Gamma equalization) Tradition
13
IGray(i, j) is the gray-level imageIEq (i, j) is the image which performed equalization IMax and IMin are the maximum and minimum of the pixel values of IGray(i, j)
![Page 14: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/14.jpg)
Power Law (Gamma equalization)
14
i is the i-th gray levelL is the low-boundR is the actual equalization rangeGE (i) is the result of the i-th gray level obtained from gamma equalization
![Page 15: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/15.jpg)
Power Law (Gamma equalization)
15
![Page 16: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/16.jpg)
Gradient Computation Masks test(for each color channel)
Gaussian (σ=0~3) 1-D point derivatives[-1,0,1] Cubic-corrected[1,-8,0,8,-1] 3X3 Sobel mask
2X2 diagonal ones
16
![Page 17: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/17.jpg)
Gradient Computation
17
‘c-cor’ is the 1D cubic-correctedpoint derivative
![Page 18: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/18.jpg)
Spatial / Orientation Binning Orientation bins are evenly spaced
0 °~180 ° 0 °~360 °
18
![Page 19: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/19.jpg)
Spatial / Orientation Binning
19
![Page 20: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/20.jpg)
Normalization and Descriptor Blocks
20
![Page 21: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/21.jpg)
Normalization and Descriptor Blocks
21
![Page 22: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/22.jpg)
Normalization and Descriptor Blocks
22
Block Normalization schemes (limiting the maximum values of
v to 0.2) and renormalizing
Centre-surround normalization Window norm(using Gaussian σ=1)
v is the unnormalized descriptor vector is a small constant
![Page 23: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/23.jpg)
Normalization and Descriptor Blocks
23
![Page 24: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/24.jpg)
Normalization and Descriptor Blocks
24
Illumination and foreground-background contrast overlap
![Page 25: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/25.jpg)
Normalization and Descriptor Blocks
25
![Page 26: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/26.jpg)
Detector Window and Context
26
![Page 27: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/27.jpg)
Classifier Using linear SVM(Support vector machine) Increasing performance
Using a Gaussian kernel Higher run time
27
![Page 28: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/28.jpg)
Classifier
28
Using a Gaussian kernel SVM,
![Page 29: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/29.jpg)
Results
29
![Page 30: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/30.jpg)
Results
30
![Page 31: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/31.jpg)
Results
31
The performance of selected detectors on (left) MIT and (right) INRIA data sets.
![Page 32: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/32.jpg)
Discussion HOG outperform wavelet & shape context Traditional centre-surround style schemes
are not the best choice Similar to SIFT descriptors
32
![Page 33: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/33.jpg)
Conclusion Scale gradients Orientation binning Relatively coarse spatial binning High-quality local contrast normalization in
overlapping descriptor blocks
33
![Page 34: Histograms of Oriented Gradients for Human Detection(HOG) Presenter :JIA-HONG,DONG Advisor : Yen- Ting, Chen 1 Dalal, N.; Triggs, B., IEEE Computer Society](https://reader030.vdocuments.us/reader030/viewer/2022032723/56649f4e5503460f94c6fd4b/html5/thumbnails/34.jpg)
Thank you for your attention
34