基於失真圖的概念對彩色影像傳真量尺的評估研究

ASSESSMENT OF THE FIDELITY METRICS FOR COLOR IMAGES BASED ON THE CONCEPT OF DISTORTION MAP

顧頌恩(Sung-En Ku)

指導教授 ： 周俊賢

大同大學/電機資訊學院/通訊工程研究所/碩士(2011年)

摘要

高品質彩色影像的重現與複製對許多數位影像處理系統而言是非常重要的。在本研究中，提出一系列色彩量尺作評估，例如RMS，CIELAB△94，S- CIELAB △94，PSPNR，設法從其中找到能夠提供與人類視覺系統對失真的重建影像品質的感知一致的量尺。本研究將對彩色影像傳真量尺的評估實驗設計成量取人眼所能感受到的失真量，或是量取超過人眼臨界可視色差(Just Noticeable Color Difference, JNCD)的失真量。所提出的彩色影像傳真量尺的正確性，將藉由原始影像與重建影像間的失真圖來驗證。
透過失真圖提供的資訊，代入各色彩量尺公式中，取得原始與重建影像各像素的失真值，所有的數據經過有條件的篩選後，再經過統計的過程得到 hit rate (HR) 與 flase alarm rate (FAR)兩組機率數值，依此繪出ROC 曲線，由此來評估各量尺的傳真度的精準性。這四個量尺以四條不同的曲線呈現，最後發現PSPNR是最符合人類視覺系统(HVS)要求的色彩量尺，這有助於未來彩色影像處理應用在不同的領域。

關鍵字

ROC 曲線 ； 假警報率 ； 命中率 ； 失真圖 ； 色彩量尺

並列摘要

High-quality color image reproduction and duplication for many digital image processing systems is very important. In the this research, the author proposes a series of color metrics for assessment, and they are RMS, CIELAB △94, S-CIELAB △94 and PSPNR, trying to find which color metric can accurately predict the response of the human visual system (HVS) to the distortion occurring in the reproduced color image. In this research, color images fidelity metric are evaluated and designed to take only the part of the distortion that is perceivable by the HVS, or the part of the distortion that exceeds just noticeable color difference (JNCD). The validity of the quality metric is verified by using the image distortion maps that are to be obtained empirically from the pairs of the original and reproduced images in the spatio-temporal domain by a number of subjects under a specified viewing condition.
In order to obtain each pixel's distortion value of the reproduction image, the information provided through distortion map is brought into the formula for each metric. All data is conditional screening through the statistical process to get two sets of probability values, hit rate (HR) and false alarm rate (FAR), and to draw the ROC curve. The four metrics demonstrate four different curves, among which PSPNR is found most consistent with human visual system (HVS), which helps the applications of color image processing in different fields in the future.

並列關鍵字

Hit Rate ； Distortion map ； Color metric ； False Al

參考文獻

[3] T. Smith and J. Guid , “The C.I.E. colorimetric standards and their use,” Transactions of the Optical Society 33, 1931-1932.

[5] L. L. Thurstone,“A Law of Comparative Judgement,”Psychological Review, vol. 34, pp. 273-286, 1927.

physiologicae,” Leipzig: Koehler, 1834.

[7] D. H. Brainard and B. A. Wandell, "Analysis of the retinex theory of color

[9] R. A. Robertson, “Historical development of CIE recommended color difference equations,” Color Research and Application, vol. 15, 1990, pp. 167-170.