應用於高動態範圍影像之新色調映射技術之研究

A New Approach to Tone Mapping for High Dynamic Range Image

竇祥庭(Hsiung-Ting Dou)

指導教授 ： 蔡吉昌

義守大學/電機資訊學院/資訊管理學系/碩士(2015年)

https://doi.org/10.6343/ISU.2015.00193

摘要

高動態範圍影像(High Dynamic Range Image; HDRI)是一個能真實表現實際景象的影像，然而這個影像卻時常無法在現實生活的顯示裝置上呈現，因為顯示裝置能顯示的影像動態範圍是非常有限，所以要將高動態範圍影像於顯示裝置上顯示，就必須做動態範圍的映射。
壓縮或展開真實景像動態範圍到顯示裝置可顯示的範圍之過程被稱為色調映射(Tone Mapping)，由於色調映射的好壞會影響顯示影像主觀的品質，因此如何建立良好的色調映射已有許多年且許多相關的論文被發表出來。
目前色調映射技術已應用於實際的生活中，且漸漸廣為一般大眾所認知是一個非常實用的技術，因此本研究論文主要的目標亦是要研究一個優質的色調映射技術，研究中先對高動態範圍影像採取全域映射(Global Mapping)處理得到低動態範圍影像，接著分析低動態範圍影像的像素對比(Contrast)的統計分布，找出低對比像素值所在範圍，接著以直方圖均化技術(Histogram Equalization)來增加低對比像素的對比，以使得低動態影像較暗或較亮區域的細節部分亦能很明顯的呈現。

關鍵字

高動態範圍影像 ； 色調映射 ； 像素對比 ； 直方圖均化技術

並列摘要

High dynamic range image is a real image that can show the actual scene, but this image cannot be rendered on the display device in real life, because dynamic range of images displayed on the display device is very limited. Therefore, before a high dynamic range image is put on display device, its dynamic range must be mapped into low dynamic range.
The process of compressing or expanding a high dynamic range image for displaying on display device is called tone mapping. For the tone mapping effects subjective quality of rendered image, hence many papers discussing how to establish good tone mapping have been published in recent years.
Currently, tone mapping techniques have been applied to real life, gradually are widely perceived by the general public, and are a very practical technology. The main goal of this thesis is to study an excellent tone mapping technique. First, take the global mapping process on high dynamic range images to obtain a low dynamic range image. Then, analyze the statistical distribution of the contrast of pixels of the low dynamic range image to find the pixels with low contrast. Last, increase the contrast of pixels with low contrast in a low dynamic range image by histogram equalization. Consequently, darker or lighter area details in a low dynamic image can also be clearly presented.

並列關鍵字

High dynamic range image ； Tone mapping ； Pixel contrast ； Histogram equalization

參考文獻

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