Introduction to Image and Video Processing
1. Analog v.s. Digital Signals
1.1 Signals
A function containing information about the behavior or nature of some phenomenon of interest.
1.2 Analog to Digital Signals
Sound : acoustic signal( x(t) ) -> electrical signal ->discrete-time signals--quantization--> discrete amplitude (the two above is called digital signals) ->electrical signal ->acoustic signal
image:
1.3 Sampling
Consider a digital image (256*256),which mean it has 256 rows and 256 columns, and it's an eight bit image which means each element of picture which is called pixel has 256 values.
如果我們down-sampling 圖片，我們就把在水平面上的value和豎直面上的value留下一個來
zero-order hold就是用一個pixel中一個的小格的數值用於其他63個小格，就會得到右一的馬賽克的圖片。
一般來說，採樣間隔越大，所得圖像像素數越少，空間分辨率低，質量差，嚴重時出現馬賽克效應；採樣間隔越小，所得圖像像素數越多，空間分辨率高，圖像質量好，但數據量大。
1.4 Quantization
8 bit的圖片相當於有256個不同灰度的values；
量化等級越多，所得圖像層次越豐富，灰度分辨率高，圖像質量好，但數據量大；量化等級越少，圖像層次欠豐富，灰度分辨率低，會出現假輪廓現象，圖像質量變差，但數據量小.
Quantization is a reversible process in the sense that you can recover the original image after it undergoes quantization.
選擇：False 量化是不可逆的
2. Image and Video Signals
沒啥好記的,都是介紹性的內容
3. Electromagnetic Spectrum
以介紹圖片爲主就不多記了