高動態範圍光場相機與其內建資料處理器設計

Abstract

近年來，各種取得四維光場資料的方法，在計算攝影學領域被提出。對這些資料做處理，可以在拍攝後，事後決定對焦的位置；或者是由四維資料直接做出場景的深度圖。我們發現在針孔陣列遮罩光場相機上，若改變針孔孔徑，可使進光量改變。因此該相機可以視作許多部小相機的組合，所以我們可以對每部相機設定不同曝光程度，以這些拍攝結果組合出高動態範圍影像。 在本篇論文中，我們設計出具有四種孔徑大小的針孔陣列遮罩，光線經過不同孔徑的針孔，就相當於不同曝光程度的相片。在一次快門時間就得到四維光場資料，而且不須校正影像間的相對位移，直接組合出高動態範圍影像。傳統作法上，不能以單一部相機只拍攝一次就得到。 由於處理原始光場資料至高動態範圍影像，需經許多計算，我們提出一個高動態範圍光場相機資料處理器，處理時可同時進行數位變焦，決定對焦在何處，並於0.3秒內得到高動態範圍結果，讓相機使用者能迅速獲得相片。以TSMC 90 nm實現，晶片尺寸為1.447 〖mm〗^2，操作頻率為100 MHz時功率消耗為: 121.9 mW。

Recently, different methods have been proposed to acquire 4-D light field data in the field of computational photography. Digitally refocusing and depth maps are available after processing 4-D light field data. In the pinhole array mask light field camera, light intensities are affected by the sizes of pinholes. Since this cameras can be regarded as an array of different small cameras, we can use these cameras to obtain high dynamic range images by assigning different exposure levels to different cameras. In this thesis, we design an array mask with four different pinhole diameters, which is equivalent to taking four pictures with different exposure levels. We can use our camera to obtain the light field data and composite a high dynamic range image with only single shot. It requires several cameras or shots for these applications traditionally. Because light field data processing is time-consuming, we design a processor to speed up calculations, where digitally refocusing and high dynamic range algorithms are performed simultaneously. All the calculations can be completed within 0.3 sec. The chip is implemented using TSMC 90 nm technology. The die size is 1.447 〖mm〗^2. The power consumption is 121.9 mW when operating at 100 MHz.