本文關(guān)鍵詞： 自動白平衡 色溫 灰度世界法 完美反射法 增益 NT96211　出處：《湖南科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：數(shù)碼相機自誕生以來，3A(自動聚焦、自動曝光、自動白平衡)算法一直是被研究的核心內(nèi)容，，本文主要是對自動白平衡算法進(jìn)行研究及實現(xiàn)。由于人類視覺具有顏色恒常性，對于在不同光源下的同一物體感知為相對恒定的顏色。而數(shù)碼相機在低色溫光源下拍攝的照片偏紅，在高色溫光源下拍攝的照片偏藍(lán)，針對這一現(xiàn)象，相機必須進(jìn)行白平衡調(diào)節(jié)。所謂白平衡從字面意思可以理解為對白色進(jìn)行調(diào)節(jié)使之到達(dá)平衡，不管在何種色溫的光源下拍攝白色的物體，都能將白色的物體還原成為原本的白色。 在研究現(xiàn)有的自動白平衡算法的前提下，為了克服灰度世界法在單一色彩的場景白平衡失效，以及圖像中有亮度很高像素存在時完美反射法失效的缺陷，本文提出了一種基于光源色溫判斷的自動白平衡算法。首先，方便計算和統(tǒng)計光源的屬性，將整幅圖像分為1616個宏塊。然后，根據(jù)提供的各種色溫下光源的R/G、B/G的范圍來確定每一個宏塊屬于哪種光源。如果超過50個宏塊屬于某種光源，則將此種光源記為100分，其他情況則根據(jù)函數(shù)關(guān)系得分。單一依靠R/G、B/G的范圍來確定光源屬性會出現(xiàn)判錯的情況，光源錯判主要以亮度為標(biāo)準(zhǔn)評價，對于光源錯判有相應(yīng)的減分原則。通過最后得分結(jié)果判斷整幅圖像的所屬光源，分?jǐn)?shù)最高的光源即為整幅圖像的光源。最后，計算白平衡增益。根據(jù)灰色法原理，在某種確定光源下白點的紅、綠、藍(lán)三基色的灰度值相等。將綠色通道的增益值確定為256，計算Rgain、Bgain的白平衡增益。 為了評估算法的白平衡調(diào)整效果，將該算法移植到NT96211搭建的硬件平臺進(jìn)行驗證。采用了主觀和客觀兩種方式來評估本文提出的白平衡算法。主觀方式主要是人眼觀察圖片，而客觀方法采用圖像處理軟件采集到的數(shù)據(jù)進(jìn)行比較客觀地分析白平衡算法的效果。兩種評估方式都表明，本文提出的白平衡算法相對于典型的算法有很大的改善。同時該算法與一般數(shù)碼相機白平衡算法最大的區(qū)別在于：它的白平衡參數(shù)是依據(jù)分析當(dāng)前幀的圖像信息得到的，而一般數(shù)碼相機白平衡算法的白平衡參數(shù)是依據(jù)拍照前最后一幀圖像的信息計算得到，故該優(yōu)勢更適合在紅外監(jiān)控類產(chǎn)品中使用。
[Abstract]:Since the digital camera was born, the algorithm of automatic focusing, automatic exposure and automatic white balance has always been the core of the research. This paper mainly studies and realizes the algorithm of automatic white balance. Because of the color constancy of human vision, In view of the fact that the same object under different light sources is perceived as a relatively constant color, and that the photos taken by a digital camera under a low color temperature light source tend to be red, and the photos taken under a high color temperature light source tend to be blue, The camera must adjust the white balance. The so-called white balance is literally understood as adjusting the white to balance, regardless of the color temperature under which white objects are photographed. Can restore the white object to the original white. On the premise of studying the existing automatic white balance algorithm, in order to overcome the failure of the gray world method in the single color scene white balance, and the defect of perfect reflection method when there are very high brightness pixels in the image, In this paper, an automatic white balance algorithm based on color temperature judgement of light source is proposed. Firstly, it is convenient to calculate and calculate the properties of light source, and the whole image is divided into 166 macroblocks. Determine what kind of light source each macroblock belongs to based on the range of R / G / B / G of the light source provided at various color temperatures. If more than 50 macroblocks belong to a certain light source, mark the light source at 100 points. In other cases, according to the function relation, the light source attribute will be judged wrong by relying solely on the range of R / G / G / B / G, and the light source error judgment is mainly based on the brightness as the standard evaluation. According to the result of the final score, the light source with the highest score is the light source of the whole image. Finally, the white balance gain is calculated. The gray values of red, green and blue primary colors are equal under a certain light source. The gain value of green channel is determined to be 256, and the white balance gain of RgainBgain is calculated. In order to evaluate the white balance adjustment effect of the algorithm, the algorithm is transplanted to the hardware platform set up by NT96211 for verification. The white balance algorithm proposed in this paper is evaluated by subjective and objective methods. The objective method uses the data collected by the image processing software to analyze the effect of the white balance algorithm objectively. The white balance algorithm proposed in this paper is much better than the typical one. At the same time, the biggest difference between the white balance algorithm and the general white balance algorithm is that the white balance parameters are obtained by analyzing the image information of the current frame. The white balance parameters of the general white balance algorithm of digital cameras are calculated according to the information of the last frame of image before taking pictures, so this advantage is more suitable for use in infrared monitoring products.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TP391.41;TB852.1

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