光學編碼器的優點

　　手機相機上的光學變焦功能避免了數碼變焦造成的質量下降，但目前的實現往往是噪音大、體積大、耗電大。Avago的aedr-8400編碼器采用了一種獨特的方法，解決了這些問題。

　　介紹

　　廣泛的商業應用使用帶有變焦機構的照相機。也許最普遍的應用是相機電話。相機變焦的關鍵設計標準包括低功耗，當然還有空間限制。本文介紹了一種光學編碼器技術，它為相機變焦設計提供了一種新的方法來應對這些挑戰。

　　光學和數字變焦

　　相機手機可能有光學變焦、數碼變焦，或者兩者都有。光學變焦改變相機鏡頭的有效焦距，使得原始圖像被放大，并可由CCD或cmos圖像傳感器捕獲。隨著放大倍數的增大，光被分散到整個圖像傳感器上，并且所有的像素都可以使用。光學變焦可以被解釋為一個真正的變焦，這將提高拍攝圖像的質量。

　　Digital zoom， on the other hand， is a bit different. In this case， a software algorithm is applied rather than a hardware movement （i.e.， changes in lens positioning） to magnify the image. Such magnification involves only a certain portion of the captured image. This is known as the interpolation technique. Using such a technique， or algorithm， requires information to be added in order to enlarge the corresponding image portion. It may seem that the captured image is being magnified. However， only a certain portion of the real image information is being utilized and the rest of the image is coming from the interpolation outputs.

　　One thing worth mentioning is that the higher the digital zoom， the smaller the portion of real information that is taken. Therefore， many of the originally captured pieces of information on the image sensor will be discarded and more interpolated image data will be incorporated in the resultant image.