ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7...
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![Page 2: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/2.jpg)
'The only limit is your imagination'
http://itchyi.squarespace.com/thelatest/2012/5/17/the-only-limit-is-your-imagination.html
![Page 3: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/3.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 20161
Lecture 7:
Convolutional Neural Networks
http://cs231n.stanford.edu/
![Page 4: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/4.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 20167
A bit of history:
Hubel & Wiesel,1959RECEPTIVE FIELDS OF SINGLE NEURONES INTHE CAT'S STRIATE CORTEX
1962RECEPTIVE FIELDS, BINOCULAR INTERACTIONAND FUNCTIONAL ARCHITECTURE INTHE CAT'S VISUAL CORTEX
1968...
![Page 5: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/5.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201622
preview:
![Page 6: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/6.jpg)
32x32x3 image
Start with an image (width x hight x depth)
![Page 7: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/7.jpg)
32x32x3 image
Let’s focus on a small area only
![Page 8: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/8.jpg)
32x32x3 image 5x5x3 filter
Let’s focus on a small area only (5x5x3)
![Page 9: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/9.jpg)
32x32x3 image
one number!
Get one number using the filter
![Page 10: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/10.jpg)
32x32x3 image
one number!
Get one number using the filter
5x5x3 filter
=Wx+b =ReLU(Wx+b)
![Page 11: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/11.jpg)
32x32x3 image
one number!
Let’s look at other areas with the same filter (w)
![Page 12: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/12.jpg)
32x32x3 image
one number!
Let’s look at other areas with the same filter (w)
![Page 13: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/13.jpg)
32x32x3 image
one number!
Let’s look at other areas with the same filter (w)
![Page 14: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/14.jpg)
32x32x3 image
one number!
Let’s look at other areas with the same filter (w)
![Page 15: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/15.jpg)
32x32x3 image
one number!
Let’s look at other areas with the same filter (w)
How many numbers can we get?
![Page 16: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/16.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201624
7x7 input (spatially)assume 3x3 filter
7
7
A closer look at spatial dimensions:
![Page 17: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/17.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201625
7x7 input (spatially)assume 3x3 filter
7
7
A closer look at spatial dimensions:
![Page 18: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/18.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201626
7x7 input (spatially)assume 3x3 filter
7
7
A closer look at spatial dimensions:
![Page 19: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/19.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201627
7x7 input (spatially)assume 3x3 filter
7
7
A closer look at spatial dimensions:
![Page 20: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/20.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201628
7x7 input (spatially)assume 3x3 filter
=> 5x5 output
7
7
A closer look at spatial dimensions:
![Page 21: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/21.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201629
7x7 input (spatially)assume 3x3 filterapplied with stride 2
7
7
A closer look at spatial dimensions:
![Page 22: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/22.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201630
7x7 input (spatially)assume 3x3 filterapplied with stride 2
7
7
A closer look at spatial dimensions:
![Page 23: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/23.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201631
7x7 input (spatially)assume 3x3 filterapplied with stride 2=> 3x3 output!
7
7
A closer look at spatial dimensions:
![Page 24: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/24.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201634
N
NF
F
Output size:(N - F) / stride + 1
e.g. N = 7, F = 3:stride 1 => (7 - 3)/1 + 1 = 5stride 2 => (7 - 3)/2 + 1 = 3stride 3 => (7 - 3)/3 + 1 = 2.33 :\
![Page 25: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/25.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201635
In practice: Common to zero pad the border0 0 0 0 0 0
0
0
0
0
e.g. input 7x73x3 filter, applied with stride 1 pad with 1 pixel border => what is the output?
(recall:)(N - F) / stride + 1
![Page 26: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/26.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201636
In practice: Common to zero pad the border
e.g. input 7x73x3 filter, applied with stride 1 pad with 1 pixel border => what is the output?
7x7 output!
0 0 0 0 0 0
0
0
0
0
![Page 27: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/27.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201637
In practice: Common to zero pad the border
e.g. input 7x73x3 filter, applied with stride 1 pad with 1 pixel border => what is the output?
7x7 output!in general, common to see CONV layers with stride 1, filters of size FxF, and zero-padding with (F-1)/2. (will preserve size spatially)e.g. F = 3 => zero pad with 1 F = 5 => zero pad with 2 F = 7 => zero pad with 3
0 0 0 0 0 0
0
0
0
0
![Page 28: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/28.jpg)
32x32x3 image
5x5x3 filter 1
Swiping the entire image
![Page 29: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/29.jpg)
32x32x3 image
5x5x3 filter 2
Swiping the entire image
![Page 30: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/30.jpg)
32x32x3 image
6 filters (5x5x3)
Swiping the entire image
activation maps (?, ?, ?)
![Page 31: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/31.jpg)
Convolution layers
32x32x3 image
![Page 32: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/32.jpg)
Convolution layers
32x32x3 image
![Page 33: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/33.jpg)
Convolution layersHow many weight variables? How to set them?
32x32x3 image
![Page 34: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/34.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201619
Preview [From recent Yann LeCun slides]
![Page 35: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/35.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201622
preview:
![Page 37: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/37.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201622
preview:
![Page 38: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/38.jpg)
Pooling layer (sampling)
conv layer
![Page 39: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/39.jpg)
Pooling layer (sampling)
conv layer
resize (sampling)
![Page 40: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/40.jpg)
Pooling layer (sampling)
conv layer
![Page 41: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/41.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201655
1 1 2 4
5 6 7 8
3 2 1 0
1 2 3 4
Single depth slice
x
y
max pool with 2x2 filters and stride 2 6 8
3 4
MAX POOLING
![Page 42: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/42.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201655
1 1 2 4
5 6 7 8
3 2 1 0
1 2 3 4
Single depth slice
x
y
max pool with 2x2 filters and stride 2 6 8
3 4
MAX POOLING
![Page 43: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/43.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201658
Fully Connected Layer (FC layer)- Contains neurons that connect to the entire input volume, as in ordinary Neural
Networks
![Page 44: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/44.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201659
http://cs.stanford.edu/people/karpathy/convnetjs/demo/cifar10.html
[ConvNetJS demo: training on CIFAR-10]
![Page 46: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/46.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 20161
Lecture 7:
Convolutional Neural Networks
http://cs231n.stanford.edu/
![Page 47: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/47.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201660
Case Study: LeNet-5[LeCun et al., 1998]
Conv filters were 5x5, applied at stride 1Subsampling (Pooling) layers were 2x2 applied at stride 2i.e. architecture is [CONV-POOL-CONV-POOL-CONV-FC]
![Page 48: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/48.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201663
Case Study: AlexNet[Krizhevsky et al. 2012]
Input: 227x227x3 images
First layer (CONV1): 96 11x11 filters applied at stride 4=>Output volume [55x55x96]Parameters: (11*11*3)*96 = 35K
![Page 49: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/49.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201666
Case Study: AlexNet[Krizhevsky et al. 2012]
Input: 227x227x3 imagesAfter CONV1: 55x55x96
Second layer (POOL1): 3x3 filters applied at stride 2Output volume: 27x27x96Parameters: 0!
![Page 50: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/50.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201667
Case Study: AlexNet[Krizhevsky et al. 2012]
Input: 227x227x3 imagesAfter CONV1: 55x55x96After POOL1: 27x27x96...
![Page 51: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/51.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201668
Case Study: AlexNet[Krizhevsky et al. 2012]
Full (simplified) AlexNet architecture:[227x227x3] INPUT[55x55x96] CONV1: 96 11x11 filters at stride 4, pad 0[27x27x96] MAX POOL1: 3x3 filters at stride 2[27x27x96] NORM1: Normalization layer[27x27x256] CONV2: 256 5x5 filters at stride 1, pad 2[13x13x256] MAX POOL2: 3x3 filters at stride 2[13x13x256] NORM2: Normalization layer[13x13x384] CONV3: 384 3x3 filters at stride 1, pad 1[13x13x384] CONV4: 384 3x3 filters at stride 1, pad 1[13x13x256] CONV5: 256 3x3 filters at stride 1, pad 1[6x6x256] MAX POOL3: 3x3 filters at stride 2[4096] FC6: 4096 neurons[4096] FC7: 4096 neurons[1000] FC8: 1000 neurons (class scores)
![Page 52: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/52.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201669
Case Study: AlexNet[Krizhevsky et al. 2012]
Full (simplified) AlexNet architecture:[227x227x3] INPUT[55x55x96] CONV1: 96 11x11 filters at stride 4, pad 0[27x27x96] MAX POOL1: 3x3 filters at stride 2[27x27x96] NORM1: Normalization layer[27x27x256] CONV2: 256 5x5 filters at stride 1, pad 2[13x13x256] MAX POOL2: 3x3 filters at stride 2[13x13x256] NORM2: Normalization layer[13x13x384] CONV3: 384 3x3 filters at stride 1, pad 1[13x13x384] CONV4: 384 3x3 filters at stride 1, pad 1[13x13x256] CONV5: 256 3x3 filters at stride 1, pad 1[6x6x256] MAX POOL3: 3x3 filters at stride 2[4096] FC6: 4096 neurons[4096] FC7: 4096 neurons[1000] FC8: 1000 neurons (class scores)
Details/Retrospectives: - first use of ReLU- used Norm layers (not common anymore)- heavy data augmentation- dropout 0.5- batch size 128- SGD Momentum 0.9- Learning rate 1e-2, reduced by 10manually when val accuracy plateaus- L2 weight decay 5e-4- 7 CNN ensemble: 18.2% -> 15.4%
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Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201675
Case Study: GoogLeNet [Szegedy et al., 2014]
Inception module
ILSVRC 2014 winner (6.7% top 5 error)
![Page 54: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/54.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201677
Slide from Kaiming He’s recent presentation https://www.youtube.com/watch?v=1PGLj-uKT1w
Case Study: ResNet [He et al., 2015]
ILSVRC 2015 winner (3.6% top 5 error)
![Page 55: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/55.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201680
Case Study: ResNet [He et al., 2015]
ILSVRC 2015 winner (3.6% top 5 error)
(slide from Kaiming He’s recent presentation)
2-3 weeks of training on 8 GPU machine
at runtime: faster than a VGGNet! (even though it has 8x more layers)
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Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201681
Case Study: ResNet[He et al., 2015]
224x224x3
spatial dimension only 56x56!
![Page 57: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/57.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201682
Case Study: ResNet [He et al., 2015]
![Page 58: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/58.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201685
Case Study: ResNet [He et al., 2015]
(this trick is also used in GoogLeNet)
![Page 59: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/59.jpg)
Convolutional Neural Networks for Sentence Classification [Yoon Kim, 2014]
![Page 60: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/60.jpg)
Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201687
Case Study Bonus: DeepMind’s AlphaGo
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Lecture 7 - 27 Jan 2016Fei-Fei Li & Andrej Karpathy & Justin JohnsonFei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 - 27 Jan 201688
policy network:[19x19x48] InputCONV1: 192 5x5 filters , stride 1, pad 2 => [19x19x192]CONV2..12: 192 3x3 filters, stride 1, pad 1 => [19x19x192]CONV: 1 1x1 filter, stride 1, pad 0 => [19x19] (probability map of promising moves)
![Page 62: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/62.jpg)
'The only limit is your imagination'
http://itchyi.squarespace.com/thelatest/2012/5/17/the-only-limit-is-your-imagination.html
![Page 63: ML with Tensorflow-new - GitHub Pages · Fei-Fei Li & Andrej Karpathy & Justin Johnson Lecture 7 -68 27 Jan 2016 Case Study: AlexNet [Krizhevsky et al. 2012] Full (simplified) AlexNet](https://reader033.fdocuments.net/reader033/viewer/2022050409/5f85e5d623d48f15c659d6e2/html5/thumbnails/63.jpg)
Next
Recurrent
Neural Nets (RNN)