以FPGA技術來實現自動亮度控制及數位影像處理

Auto Brightness Control and Digital Image Processing by FPGA Technique

簡鴻文(Hung-Wen Chien)

指導教授 ： 宋國明

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2010年)

摘要

本篇論文主要是利用硬體描述語言來撰寫即時影像處理與自動亮度控制的硬體架構，其設計原理係採用計算影像的亮度值(Intensity)來偵測整張影像平均亮度，得到平均亮度後可以辨別出影像是否太亮或者太暗，再經過自動亮度調整機制，可以將影像調整到適中的亮度值，讓人的視覺比較舒適。

首先，將影像資料存入快閃記憶體(Flash Memory)內，接著將快閃記憶體裡面的影像讀取到記憶體裡面，讀取影像同時會將影像的RGB 三原色的數值轉成亮度數值，轉換的方式可以使用RGB轉YCbCr的公式來計算，YCbCr中的Y表示亮度的意思；轉換YCbCr時需要用到浮點的運算以及除法運算，在FPGA（Field Programmable Gate Array）架構裡面使用除法運算是比較耗資源，因此本篇的論文主要使用快速位移(Shift)的方式來實做RGB轉亮度值(Intensity)的運算。

最後的實驗結果將一張很暗的影像以及很亮的影像調整到適中的亮度，也證明了自動亮度影像處理確實改善了畫面品質，本論文提供的方法成功的與液晶面板結合，使得顯示的畫面能夠更好。

關鍵字

FPGA ； Verilog硬體描述語言 ； 影像處理 ； 自動亮度 ； 即時影像處理 ； 液晶顯示器

並列摘要

This thesis focuses on the FPGA utilization for hardware architecture of real time image processing and automatic brightness control. The designed principle is to monitor the average brightness of whole image by calculating its intensity. If the average intensity value, which is used to evaluate the sufficient of bright, was uncomfortable, we can regulate the proper intensity to provide the user a suitable intensity.

Firstly, the image data needs to be put into flash memory and then read it to system memory. Meanwhile, it needs to convert the RGB data to calculate the intensity value via RGB-to-YCbCr formula. The conversion process includes some multiplications and divisions of floating point operation. In the architecture of Field Programmable Gate Array (FPGA), division would cause more resource consumption; then a rapid shift method is provided to calculate the intensity of RGB.

According to experiment result, a low intensity image can be adjusted to a suitable intensity image and quality of it can be improved by automatic brightness image processing. Contribution of this thesis is to provide an image algorithm integrated FPGA to improved quality of an image.

並列關鍵字

FPGA ； Verilog ； Image processing ； Auto brightness ； Real-time image processing ； LCD

參考文獻

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