1) Capsule networks use vectors instead of scalar outputs from neurons to capture spatial relationship information between objects, unlike traditional CNNs. 2) Dynamic routing replaces max pooling by using an iterative routing-by-agreement mechanism to determine the influence weights between capsules in different layers. 3) Experiments on digit classification show that capsule networks with dynamic routing outperform CNNs while using less data augmentation due to their ability to better preserve spatial relationships under transformations like scaling and translation.

1. Deep Learning Advance
# Capsule Net
Terence Huang

2. Abstact
• Paper
- (2017) Dynamic Routing Between Capsules
- (2018) Matrix Capsules with EM Routing
• Abstract
- Capsules: 用向量代替元素輸出，可捕捉空間結構信息的膠囊概念
- Dynamic Routing: 用 routing-by-agreement 取代 max-pooling
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3. Outline
• Drawbacks of CNN
• Capsule
• Dynamic Routing
• Experiments
- 數字分類
- Train 時額外提供少量標記的 test set
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4. Drawbacks of CNN
• Drawbacks of CNN
- Pooling weak
- Ambivalent the spatial relationships of the previous layer
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15 9 4 2
11 5 8 6
8 7 3 17
2 3 7 3
15 8
8 17
10 5
5 8
Max pooling
Average pooling
Only keep partial feature
Max is define by input layer, not Bi-layer
旋轉縮放和平移不變性，適應程度較小，需要大量 augmentation 協助
Weight are equal
Who

5. Capsule
• Capsule
- 用向量代替元素輸出，可捕捉空間結構信息的膠囊概念
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Tradition NN Capsule Net
Unit: List of objects
objects can be different attributes
Unit: One object
Ex. value, one-hot vector, pixel

6. Dynamic Routing
• Dynamic Routing
- 用 routing-by-agreement 取代 max-pooling
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7. • Dynamic Routing
- 用 routing-by-agreement 取代 max-pooling
Dynamic Routing
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⋯ ⋯
Layer I Layer JLayer A Layer B Layer C Layer ZLayer Y

8. Dynamic Routing
• Dynamic Routing
- 用 routing-by-agreement 取代 max-pooling
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定義
𝑊𝑖𝑗, 𝐶𝑖𝑗
Layer I Layer J
Layer I：3 個 capsules, 𝑖 = 𝑅, 𝐺, 𝐵
Layer J：2 個 capsules, 𝑗 = 1,2
𝑊𝑖𝑗: 傳統 CNN 的權重
由 backpropagation 計算，Dynamic Routing 迭代過程中不改變
𝐶𝑖𝑗: capsule 𝑖 對 capsule 𝑗 的影響力，迭代過程中自行調整
𝑖 𝐶𝑖𝑗 = 1，迭代開始時影響力皆均等

9. Dynamic Routing
• Dynamic Routing
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幾乎傳一樣
所以不能迭代太多次
R
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1st 迭代後
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G
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2nd 迭代後
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G
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nth 迭代後
𝑊𝑖𝑗, 𝐶𝑖𝑗
𝑊𝑖𝑗: 傳統 CNN 的權重，不變
𝐶𝑖𝑗: 𝑖 對 𝑗 的影響力，迭代改變
Layer I Layer J
1 = 𝑖=𝑅,𝐺,𝐵 𝐶𝑖1 ⋅ 𝑊𝑖1 ⋅ capsule 𝑖
𝑊𝑖𝑗, 𝐶𝑖𝑗𝑊𝑖𝑗, 𝐶𝑖𝑗 𝑊𝑖𝑗, 𝐶𝑖𝑗
更新 𝐶𝑖𝑗 ⇒ 𝐶 𝑅1 ↑, 𝐶G1 ↓, 𝐶 𝐵1 ↓,
𝐶 𝑅2 ↓, 𝐶G2 ↓, 𝐶 𝐵2 ↑
再更新 𝐶𝑖𝑗 ⇒ 𝐶 𝑅1 ↑, 𝐶G1 ↓, 𝐶 𝐵1 ↓,
𝐶 𝑅2 ↓, 𝐶G2 ↓, 𝐶 𝐵2 ↑
新的
初始均等
定義

10. • Dynamic Routing
- ex. rounting 次數: 3
Dynamic Routing
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Layer I Layer J
⋯ ⋯
調整 𝐶𝑖𝑗
調整 𝑊𝑖𝑗
⋯
⋯
𝐶𝑖𝑗 的傳遞 & 修正
W𝑖𝑗 的傳遞 & 修正
Layer A Layer B Layer C Layer ZLayer Y

11. Dynamic Routing
• Dynamic Routing
- 用 routing-by-agreement 取代 max-pooling
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壓縮到 [0,1) 保留向量特徵

12. Recall
• Paper
- (2017) Dynamic Routing Between Capsules
- (2018) Matrix Capsules with EM Routing
• Abstract
- Capsules: 用向量代替元素輸出，可捕捉空間結構信息的膠囊概念
- Dynamic Routing: 用 routing-by-agreement 取代 max-pooling
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13. Q&A
Thanks for your attention!
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