January 2019
Beginner to intermediate
576 pages
14h 31m
Chinese
Content preview from 深度學習｜內行人的做法
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364
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第八章：向量化
圖片格式
每一種格式都採用不同的方式儲存圖片資料，並對原始資料執行不同等級
的壓縮。圖片與文字有所不同，相較之下圖片的向量化做法會比較直接
一點。
處理影片資料
影片資料向量化是圖片向量化與時間序列向量化的綜合體。在影片資料
中，我們會有一系列帶有時間戳（timestamp）的圖片。影片的向量化過
程必須隨時間追蹤圖片向量化的結果，而且以我們所考慮的單一向量而言
（例如採用單一畫格，或是跨越多個畫格的圖片子集），情況有可能還會
變得更加複雜。
圖片資料在 DL4J 中的表達方式
在深度學習的領域中，我們最感興趣的就是 CNN 的圖片向量化做法。在 DL4J 中，我們
會用
INDArray
物件把每個圖片轉換成三維張量表達方式（更多關於這個主題的介紹，請
參見附錄 E 的內容），如圖 8-1 所示。
轉換函數 激活函數
激活值
淨輸入
輸入立方體
（特別強調過濾器關注的部分）
過濾器
人工神經元模型細節
神經元
圖 8-1 CNN 的三維輸入立方體
圖片資料的向量化
|
365
我們在建立圖片的小批量資料以做為訓練之用時，正如本書範例中所見，我們實際上是
在建立具有以下維度的四維張量：
1. 小批量數量
2. 深度
3. 高度
4. 寬度
其中寬度與高度直接對映到輸入圖片的寬度與高度，深度則是圖片資料中顏色通道的數 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.