攝像裝置之空間解析力評估

Abstract

近年來手機、平板電腦此類行動裝置的普及，使得每個人手上幾乎皆具備了攝像裝置，可做為一種簡單、快速的量測工具。隨著相機製作技術進步，相機品質也越來越高，而做為一個量測工具，相機所能還原真實世界的細節程度則影響了影像的可用性，藉由空間解析力的評估得到相機的量化品質。空間解析力的評估方法有很多種，如調制轉換函數、模糊參數及盲評估法等方法，其中模糊參數之成果具有唯一性，便於直觀的評比差異。本研究中使用量測型相機Microsoft UltraCamXp及非量測型相機Canon 650D、Nikon D80、Sony NEX3與智慧型行動電話HTC DesireHD所拍攝的影像，並以模糊參數計算結果並與調制轉換函數標準差進行比較，探討模糊參數對於數種物理變化的空間解析力差異，如對焦、光照不均、影像尺寸與相機種類。而結果顯示在各個案例中，模糊參數間關係均能與物理現象吻合。

In recent years, the mobile device is becoming popular. Almost everyone has an imaging device, which can be a simple and fast measurement tool. With the advent of camera technology, the quality of resulting image is also improving. Spatial resolution could be one of the quantitative measures. Modulation transfer function, blur parameter, blind estimation could be applied. Among these, blur parameter scheme provides an easy scheme. In this study, images obtained with Microsoft UltraCam Xp, which is categorized as a metric camera, and non-metric cameras such as Canon 650D, Nikon D80, Sony NEX3 and HTC DesireHD are used in the experiment. Spatial resolution is calculated with blur parameter scheme, and compare with the standard deviation of the modulation transfer function. The results agree generally with different physical phenomena, such as focusing, uneven illumination, image size. Comparison among several consumer grade cameras is also conducted.