Deep Learning in Computer Vision
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Deep Learning in Computer Vision Applications 1. Basics on Convolutional Neural Network 2. Otimization Methods (Momentum, AdaGrad, RMSProp, Adam, etc) 3. Semantic Segmentation 4. Class Activation Map 5. Object Detection 6. Recurrent Neural Network 7. Visual Question and Answering 8. Word2Vec (Word embedding) 9. Image Captioning
![Solving VQA
163
Approach
[Malinowski et al., 2015] [Ren et al., 2015] [Andres et al., 2015]
[Ma et al., 2015] [Jiang et al., 2015]
Various methods have been proposed](https://image.slidesharecdn.com/dlincv-161110052148/85/Deep-Learning-in-Computer-Vision-163-320.jpg)
![DPPnet
168
Weight Sharing with Hashing Trick
Weights of Dynamic Parameter Layer are picked from Candidate weights by Hashing
Question Feature
Candidate Weights
fc-layer
0.11.2-0.70.3-0.2
0.1 0.1 -0.2 -0.7
1.2 -0.2 0.1 -0.7
-0.7 1.2 0.3 -0.2
0.3 0.3 0.1 1.2
DynamicParameterLayer
Hasing
[Chen et al., 2015]](https://image.slidesharecdn.com/dlincv-161110052148/85/Deep-Learning-in-Computer-Vision-168-320.jpg)
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Deep Learning in Computer Vision
- 1. Introduction to Deep Learning Presenter: Sungjoon Choi ([email protected])
- 2. Optimization methods CNN basics Semantic segmentation Weakly supervised localization Image detection RNN Visual QnA Word2Vec Image Captioning Contents
- 3. What is deep learning? 3 “Deep learning is a branch of machine learning based on a set of algorithms that attempt to model high-level abstractions in data by using multiple processing layers, with complex structures or otherwise, composed of multiple non-linear transformations.” Wikipedia says: Machine Learning High-level abstraction Network
- 4. Is it brand new? 4 Neural Nets McCulloch & Pitt 1943 Perception Rosenblatt 1958 RNN Grossberg 1973 CNN Fukushima 1979 RBM Hinton 1999 DBN Hinton 2006 D-AE Vincent 2008 AlexNet Alex 2012 GoogLeNet Szegedy 2015
- 5. Deep architectures 5 Feed-Forward: multilayer neural nets, convolutional nets Feed-Back: Stacked Sparse Coding, Deconvolutional Nets Bi-Directional: Deep Boltzmann Machines, Stacked Auto-Encoders Recurrent: Recurrent Nets, Long-Short Term Memory
- 6. CNN basics
- 7. CNN 7 CNNs are basically layers of convolutions followed by subsampling and fully connected layers. Intuitively speaking, convolutions and subsampling layers works as feature extraction layers while a fully connected layer classifies which category current input belongs to using extracted features.
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- 19. Gradient descent? There are three variants of gradient descent Differ in how much data we use to compute gradient We make a trade-off between the accuracy and computing time
- 20. Batch gradient descent In batch gradient decent, we use the entire training dataset to compute the gradient.
- 21. Stochastic gradient descent In stochastic gradient descent (SGD), the gradient is computed from each training sample, one by one.
- 22. Mini-batch gradient decent In mini-batch gradient decent, we take the best of both worlds. Common mini-batch sizes range between 50 and 256 (but can vary).
- 23. Challenges Choosing a proper learning rate is cumbersome. Learning rate schedule Avoiding getting trapped in suboptimal local minima
- 24. Momentum
- 26. Adagrad It adapts the learning rate to the parameters, performing larger updates for infrequent and smaller updates for frequent parameters. 𝜃𝑡+1,𝑖 = 𝜃𝑡,𝑖 − 𝜂 𝐺𝑡,𝑖𝑖 + 𝜖 𝑔𝑡,𝑖 Performing larger updates for infrequent and smaller updates for frequent parameters.
- 27. Adadelta Adadelta is an extension of Adagrad that seeks to reduce its monotonically decreasing learning rate. It restricts the window of accumulated past gradients to some fixed size 𝑤. 𝐸 𝑔2 𝑡 = 𝛾𝐸 𝑔2 𝑡−1 + 1 − 𝛾 𝑔𝑡 2 𝐸 ∆𝜃2 𝑡 = 𝛾𝐸 ∆𝜃2 𝑡−1 + 1 − 𝛾 ∆𝜃𝑡 2 𝜃𝑡+1 = 𝜃𝑡 − 𝐸 ∆𝜃2 𝑡 + 𝜖 𝐸 𝑔2 𝑡 + 𝜖 𝑔𝑡 No learning rate!
- 29. RMSprop RMSprop is an unpublished, adaptive learning rate method proposed by Geoff Hinton in his lecture.. 𝐸 𝑔2 𝑡 = 𝛾𝐸 𝑔2 𝑡−1 + 1 − 𝛾 𝑔𝑡 2 𝜃𝑡+1 = 𝜃𝑡 − 𝜂 𝐸 𝑔2 𝑡 + 𝜖 𝑔𝑡
- 30. Adam Adaptive Moment Estimation (Adam) stores both exponentially decaying average of past gradients and and squared gradients. 𝑚 𝑡 = 𝛽1 𝑚 𝑡−1 + 1 − 𝛽1 𝑔𝑡 𝑣 𝑡 = 𝛽2 𝑣 𝑡−1 + 1 − 𝛽2 𝑔𝑡 2 𝜃𝑡+1 = 𝜃𝑡 − 𝜂 𝑣 𝑡 + 𝜖 1 − 𝛽2 𝑡 1 − 𝛽1 𝑡 𝑚 𝑡 Momentum Running average of gradient squares
- 31. Adam Adaptive Moment Estimation (Adam) stores both exponentially decaying average of past gradients and and squared gradients. 𝑚 𝑡 = 𝛽1 𝑚 𝑡−1 + 1 − 𝛽1 𝑔𝑡 𝑣 𝑡 = 𝛽2 𝑣 𝑡−1 + 1 − 𝛽2 𝑔𝑡 2 𝜃𝑡+1 = 𝜃𝑡 − 𝜂 𝑣 𝑡 + 𝜖 1 − 𝛽2 𝑡 1 − 𝛽1 𝑡 𝑚 𝑡
- 32. Visualization
- 34. Semantic Segmentation? lion dog giraffe Image Classification bicycle person ball dog Object Detection person person person person person bicyclebicycle Semantic Segmentation
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- 45. Results 45
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- 73. Results 73
- 74. Results 74
- 78. Weakly Supervised Object Localization 78 Usually supervised learning of localization is annotated with bounding box What if localization is possible with image label without bounding box annotations? Today’s seminar: Learning Deep Features for Discriminative Localization 1512.04150v1 Zhou et al. 2015 CVPR2016
- 79. Architecture 79 AlexNet+GAP+places205 Living room 11x11 Avg Pooling: Global Average Pooling (GAP) 11x11x512 512 205 227x227x3
- 80. Class activation map (CAM) 80 • Identify important image regions by projecting back the weights of output layer to convolutional feature maps. • CAMs can be generated for each class in single image. • Regions for each categories are different in given image. • palace, dome, church …
- 81. Results 81 • CAM on top 5 predictions on an image • CAM for one object class in images
- 82. GAP vs. GMP 82 • Oquab et al. CVPR2015 Is object localization for free? weakly-supervised learning with convolutional neural networks. • Use global max pooling(GMP) • Intuitive difference between GMP and GAP? • GAP loss encourages identification on the extent of an object. • GMP loss encourages it to identify just one discriminative part. • GAP, average of a map maximized by finding all discriminative parts of object • if activations is all low, output of particular map reduces. • GMP, low scores for all image regions except the most discriminative part • do not impact the score when perform MAX pooling
- 83. GAP & GMP 83 • GAP (upper) vs GMP (lower) • GAP outperforms GMP • GAP highlights more complete object regions and less background noise. • Loss for average pooling benefits when the network identifies all discriminative regions of an object
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- 85. Concept localization 85 Concept localization in weakly labeled images • Positive set: short phrase in text caption • Negative set: randomly selected images • Model catch the concept, phrases are much more abstract than object name. Weakly supervised text detector • Positive set: 350 Google StreeView images that contain text. • Negative set: outdoor scene images in SUN dataset • Text highlighted without bounding box annotations.
- 86. Image detection
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- 102. Results 102
- 103. SPPnet
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- 113. Results 113
- 114. Results 114
- 115. Fast R-CNN
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- 126. Faster R-CNN
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- 139. Results 139
- 140. Results 140
- 141. R-CNN 141 Image Regions Resize Convolution Features Classify
- 142. SPP net 142 Image Convolution Features SPPRegions Classify
- 143. R-CNN vs. SPP net 143 R-CNN SPP net
- 144. Fast R-CNN 144 Image Convolution Features Regions RoI Pooling Layer Class Label Confidence RoI Pooling Layer Class Label Confidence
- 145. R-CNN vs. SPP net vs. Fast R-CNN 145 R-CNN SPP net Fast R-CNN
- 146. Faster R-CNN 146 Image Fully Convolutional Features Bounding Box Regression BB Classification FastR-CNN
- 147. R-CNN vs. SPP net vs. Fast R-CNN 147 R-CNN SPP net Fast R-CNN Faster R-CNN
- 148. 148 Results
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- 154. RNN
- 157. LSTM comes in! 157 Long Short Term Memory This is just a standard RNN. http://colah.github.io/posts/2015-08-Understanding-LSTMs/
- 158. LSTM comes in! 158 Long Short Term Memory This is just a standard RNN.This is the LSTM! http://colah.github.io/posts/2015-08-Understanding-LSTMs/
- 159. Overall Architecture 159 (Cell) state Hidden State Forget Gate http://colah.github.io/posts/2015-08-Understanding-LSTMs/ Input Gate Output Gate Next (Cell) State Next Hidden State Input Output Output = Hidden state
- 161. Visual QnA
- 162. VQA: Dataset and Problem definition 162 VQA dataset - Example Q: How many dogs are seen? Q: What animal is this? Q: What color is the car? Q: What is the mustache made of?Q: Is this vegetarian pizza?
- 163. Solving VQA 163 Approach [Malinowski et al., 2015] [Ren et al., 2015] [Andres et al., 2015] [Ma et al., 2015] [Jiang et al., 2015] Various methods have been proposed
- 164. DPPnet 164 Motivation Common pipeline of using deep learning for vision CNN trained on ImageNet Switch the final layer and fine-tune for the New Task In VQA, Task is determined by a question Observation:
- 165. DPPnet 165 Main Idea Switching parameters of a layer based on a question Dynamic Parameter Layer Question Parameter Prediction Network
- 166. DPPnet 166 Parameter Explosion Number of parameter for fc-layer (R): DynamicParameterLayer Question Feature Predicted Parameter M N Q P : Dimension of hidden state fc-layer N=Q×P R=Q×P×M Q=1000, P=1000, M=500 For example: R=500,000,000 1.86GB for single layer Number of parameters for VGG19: 144,000,000
- 167. DPPnet 167 Parameter Explosion Number of parameter for fc-layer (R): DynamicParameterLayer Question Feature Predicted Parameter M N Q P : Dimension of hidden state fc-layer Solution: R=Q×P×M R= N×M N=Q×P N<Q×P We can control N
- 168. DPPnet 168 Weight Sharing with Hashing Trick Weights of Dynamic Parameter Layer are picked from Candidate weights by Hashing Question Feature Candidate Weights fc-layer 0.11.2-0.70.3-0.2 0.1 0.1 -0.2 -0.7 1.2 -0.2 0.1 -0.7 -0.7 1.2 0.3 -0.2 0.3 0.3 0.1 1.2 DynamicParameterLayer Hasing [Chen et al., 2015]
- 169. DPPnet 169 Final Architecture End-to-End Fine-tuning is possible (Fully-differentiable)
- 170. DPPnet 170 Qualitative Results Q: What is the boy holding? DPPnet: surfboard DPPnet: bat
- 171. DPPnet 171 Qualitative Results Q: What animal is shown? DPPnet: giraffe DPPnet: elephant
- 172. DPPnet 172 Qualitative Results Q: How does the woman feel? DPPnet: happy Q: What type of hat is she wearing? DPPnet: cowboy
- 173. DPPnet 173 Qualitative Results Q: How many cranes are in the image? DPPnet: 2 (3) Q: How many people are on the bench? DPPnet: 2 (1)
- 174. How to combine image and question? 174
- 175. How to combine image and question? 175
- 176. How to combine image and question? 176
- 177. How to combine image and question? 177
- 178. How to combine image and question? 178
- 179. How to combine image and question? 179
- 180. How to combine image and question? 180
- 181. How to combine image and question? 181
- 182. Multimodal Compact Bilinear Pooling 182
- 183. Multimodal Compact Bilinear Pooling 183
- 184. Multimodal Compact Bilinear Pooling 184
- 185. Multimodal Compact Bilinear Pooling 185
- 188. Results 188
- 189. Results 189
- 190. Results 190
- 191. Results 191
- 192. Results 192
- 193. Results 193
- 194. Word2Vec
- 195. Word2vec? 195
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- 209. Image Captioning
- 212. Language Model 212
- 213. Language Model 213
- 214. Language Model 214
- 215. Language Model 215
- 216. Language Model 216
- 217. Training phase 217
- 218. Training phase 218
- 219. Training phase 219
- 220. Training phase 220
- 221. Training phase 221
- 222. Training phase 222
- 223. Test phase 223
- 224. Test phase 224
- 225. Test phase 225
- 226. Test phase 226
- 227. Test phase 227
- 228. Test phase 228
- 229. Test phase 229
- 230. Test phase 230
- 231. Test phase 231
- 232. Results 232
- 233. Results 233
- 234. But not always.. 234
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- 236. Show, attend and tell 236
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- 241. Results 241
- 242. Results 242
- 244. Neural Art
- 245. Preliminaries 245 Understanding Deep Image Representations by Inverting Them CVPR2015 Texture Synthesis Using Convolutional Neural Networks NIPS2015
- 246. A Neural Algorithm of Artistic Style 246
- 247. A Neural Algorithm of Artistic Style 247
- 248. 248 Texture Synthesis Using Convolutional Neural Networks -NIPS2015 Leon A. Gatys, Alexander S. Ecker, Matthias Bethge
- 249. Texture? 249
- 250. Visual texture synthesis 250 Which one do you think is real? Right one is real. Goal of texture synthesis is to produce (arbitrarily many) new samples from an example texture.
- 251. Results of this work 251 Right ones are given sources!
- 252. How? 252
- 253. Texture Model 253 𝑋 𝑎 Input a 𝐹𝑎 1 𝐹𝑎 2 𝐹𝑎 3 𝑋 𝑏 Input b 𝐹𝑏 1 𝐹𝑏 2 𝐹𝑏 3 number of filters
- 254. Feature Correlations 254 𝑋 𝑎 Input a 𝐹𝑎 1 𝐹𝑎 2 𝐹𝑎 3 𝑋 𝑏 Input b 𝐹𝑏 1 𝐹𝑏 2 𝐹𝑏 3 number of filters 𝐺 𝑎 2 = 𝐹𝑎 2 𝑇 𝐹𝑎 2 (Gram matrix)
- 255. Feature Correlations 255 𝐺 𝑎 2 𝐹𝑎 2 𝐹𝑎 2 = number of filters W*H 𝐹𝑎 2 𝐺 𝑎 2 = 𝐹𝑎 2 𝑇 𝐹𝑎 2 (Gram matrix) number of filters
- 256. Texture Generation 256 𝑋 𝑎 Input a 𝐹𝑎 1 𝐹𝑎 2 𝐹𝑎 3 𝑋 𝑏 Input b 𝐹𝑏 1 𝐹𝑏 2 𝐹𝑏 3 𝐺 𝑎 1 𝐺 𝑏 1 𝐺 𝑎 1 𝐺 𝑏 1 𝐺 𝑎 1 𝐺 𝑏 1
- 257. Texture Generation 257 𝑋 𝑎 Input a 𝐹𝑎 1 𝐹𝑎 2 𝐹𝑎 3 𝑋 𝑏 Input b 𝐹𝑏 1 𝐹𝑏 2 𝐹𝑏 3 𝐺 𝑎 1 𝐺 𝑏 1 𝐺 𝑎 1 𝐺 𝑏 1 𝐺 𝑎 1 𝐺 𝑏 1 Element-wise squared loss Total layer-wise loss function
- 258. Results 258
- 259. Results 259
- 260. 260 Understanding Deep Image Representations by Inverting Them -CVPR2015 Aravindh Mahendran, Andrea Vedaldi (VGGgroup)
- 261. Reconstruction from feature map 261
- 262. Reconstruction from feature map 262 𝑋 𝑎 Input a 𝐹𝑎 1 𝐹𝑎 2 𝐹𝑎 3 𝑋 𝑏 Input b 𝐹𝑏 1 𝐹𝑏 2 𝐹𝑏 3 number of filters Let’s make this features similar! By changing the input image!
- 263. Receptive Field 263
- 264. 264 A Neural Algorithm of Artistic Style Leon A. Gatys, Alexander S. Ecker, Matthias Bethge
- 265. How? 265 Style Image Content Image Mixed ImageNeural Art
- 266. How? 266 Style Image Content Image Mixed ImageNeural Art Texture Synthesis Using Convolutional Neural Networks Understanding Deep Image Representations by Inverting Them
- 267. How? 267 Gram matrix
- 268. Neural Art 268 𝑝: original photo, 𝑎: original artwork 𝑥: image to be generated Content Style Total loss = content loss + style loss
- 269. Results 269
- 270. Results 270
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