图像的感知与获取

图像的感知与获取Image sensing and acquisition

图像是由“照射”源和形成图像的“场景”元素对光能的反射或吸收相结合而产生的。

传感器装置用来把照射量变为数字图像。

原理：通过将输入电功率和对特殊类型检测能源敏感的传感器材料组合，把输入能源转变为电压。输出电压波形是传感器的响应，同时，一个数字量可从数字化该响应的每个传感器得到。

图像感知的方法

• Using single sensor, such as photodiode.
• Using linear sensor strip, such as line Charge Coupled Devices(CCD), Scanner, etc.
• Using circular sensor strip（常用于医学映像）
• Using sensor arrays, such as CCD array, etc.（数码相机，二维阵列传感）

🎯A simple image formation model——一个简单的图像形成模型

2-D brightness function: f (x, y)
Brightness is a measure of the energy , f(x, y)must be nonzero and finite

当一个图像产生时，光度值正比于物理源所辐射的能量，f(x,y)一定时非零的并且时有限的

\[0<f(x,y)<∞ \]

The function f(x, y) may be characterized by two components:
(1) the amount of source illumination incident on the scene viewed: i(x, y)

入射到被观察场景的光源照射总量，称为入射分量用i(x,y)表示

(2) the amount of illumination reflected by the objects in the scene: r(x, y)

场景中物体反射的光照总量，称为反射分量用r(x,y)表示

The nature of i (x, y) is determined by the illumination source

i(x,y)的性质有光源决定

\[0<i(x,y)<∞ \]

r (x, y) is determined by the characteristics of the imaged objects

r(x,y)由场景物体反射率决定

\[0<r(x,y)<1 \]

f (x, y) is proportional to i (x, y) and r (x, y)

f(x,y)可由i(x,y)和r(x,y)表示成：

\[f(x,y) = i(x,y)r(x,y) \]

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