むらの定量化について IEC-TC110 HHG2 への提案をベースに ソニー株式会社冨岡聡 フラットパネルディスプレイの人間工学シンポジウム

Transcription

1 むらの定量化について IEC-TC110 HHG2 への提案をベースに ソニー株式会社冨岡聡

2 むら を 定量化する とは? どちらも輝度分布の最大最小の差は 22% 画面の 4 隅に向かって暗くなる状態は 気にならない 気になるもの むら むら とは人の主観である 気になる要素 を見出し 計測可能にする

3 SEMU: 既存の定量評価方法 SEMI: 半導体 FPD ナノテクノロジー MEMS 太陽光発電 その他関連技術の製造装置 材料 関連サービスを提供している企業の国際的な工業会です SEMI D31 FPD 画質検査における輝度ムラの計量単位 (Semu) の定義 2002 年 :D 規格化 Revice:D ( 視距離ファクタの導入 対象サイズの拡張 ) 人間のムラの検知限界 (JND) でのコントラストと面積の関係 1 1) Cjnd = Sjnd 対象のムラの程度 Semu は以下の式で算出する Cx 2) SEMU = 1.97(1/ 0.33 ) S x Cjnd: 検知限界におけるムラの濃さ ( コントラスト ) Sjnd: 上記濃さにおける限界ムラ面積 (mm 2 ) SEMU:SEMI Mura の略号 Cx: 対象むらの平均コントラスト Sx: 対象むらの面積 (mm 2 ) ムラのオブジェクトを抽出した上で 1) 式による判定 及び 2) 式による計算を行う ムラのオブジェクトイメージ < 問題点 > オブジェクト抽出方法が困難 ( 背景がフラットでない場合等 ): 各自で閾値のルールを作る必要がある 実面積による計算故 画面サイズによらずオブジェクトの値は同じになる 輝度にしか対応していない

4 以下英文資料は 2012 年 Boston での IEC-TC110 HHG2 Mtg. で使用したもの Measurement Method of Mura for a Flat Panel Display Screen

5 Outline Conception of a quantitative mura evaluation method Quantitative evaluation method of mura Derivation method of the formula for quantitative evaluation Subjective evaluation method Index extraction method from the measurement data The formula of luminance mura evaluation The formula of color mura evaluation The formula of general mura evaluation ( integrated both luminance and color mura evaluation ) Summary

6 Goal of a Quantitative Mura Measurement

7 The Conception of a Derivation Method of a Quantitative Evaluation

8 Subjective Evaluation Method Magnitude Estimate Method S. S. Stevens, On the Psychophysical Law, Psychological Review vol. 64, No. 3, pp (1957) Psychophysical measurement method This method provides a perceptual measure of sensation strength to the stimulus Subjective Evaluation Evaluation Stimulus A Standard Stimulus 50 Evaluation Stimulus B

9 Measurement Data Conversion to the Perceived Image

10 Visual Spatial Sensitivity Filter Utilizing of S-CIELAB model Zhang & Wandell (1997) A spatial extension of CIELAB for digital color image reproduction Journal of SID, vol.5, pp Consideration of directivity dependence in spatial frequency characteristics of human eye Yoichi Miyake, et al. (2001) Measurement and Modeling for the Two Dimensional MTF of Human Eye and Its Application for Digital Color Reproduction IS&T and SID Ninth Color Imaging Conference, 2001: p

11 Derivation of Mura Formula Bright area Dark area Luminance edge area Color mura area Chroma edge area Subjective Evaluation Values Multiple Regression Analysis Define significant indexes Y=a Xa+b Xb+c Xc+ Xi:value of significant index(i) Various kinds of numerical Indexes extracted from the Mura image number of edge bright / dark area luminance edge area luminance edge length maximum luminance difference threshold of edge threshold of bright / dark etc.

12 Luminance mura evaluation method Y Lum = 1.90 X a X b X c Luminance mura area Maximum luminance difference Luminance edge area Observers: 40 persons (male x 20, female x20) Mura evaluation pattern: 32 patterns R 2 : 0.92 Verification test Observers: 50 persons (male x 25, female x25) Mura evaluation pattern: 32 patterns R 2 : 0.94 International conference presentation IDW 08: VHFp-5 Subjective Evaluation for Indistinct Mura of LED backlight IDW 09: VHFp-15 A Quantitative Evaluation Method for Indistinct Mura of LED Backlight IDW 11: VHF4-1 Quantitative Evaluation Method for Luminance and Color Uniformity of a Display Screen Based on Human Perceptions

13 -a * Group Correction of a * value considering of hue influence +b * Group +a * Group b * b * C * a * * mod a * a * = α a * * 2 * 2 ( α a ) b C = + -b * Group 3 Subjective Evaluation Value % 10% 20% 30% +a* 40% group 50% -1 -a* group +b* group -b* group -2 Color Mura area International conference presentation SID 2010: Applied Vision P-48 Quantitative Evaluation Method for the White Uniformity of a Large-sized LED Backlight EuroDisplay 2011: Session 10-3 Quantitative Evaluation Method for Color Uniformity of a Display Screen Based on Human Perceptions

14 Color mura evaluation method Y Color = 3.97 X d X e X f Color mura area International conference presentation SID 2010: Applied Vision P-48 Quantitative Evaluation Method for the White Uniformity of a Large-Sized LED Backlight IDW 10: VFH1-5L Influence of Multi-colored Unevenness on White Uniformity Evaluation of an LED Backlight EuroDisplay 2011: Session 10-3 Quantitative Evaluation Method for Color Uniformity of a Display Screen Based on Human Perceptions Maximum chroma Chroma edge area Subjects: 40 persons (male x 20, female x20) Mura evaluation pattern: patterns: 80 patterns Coefficient of determination: 0.92 Verification test1, 2 Subjects: 140 persons (male x 20, female x20) 250 persons (male x 25, female x25) Mura evaluation pattern: 1, 2 20 patterns R 2 :

15 General mura evaluation method Y Gen = Y Lum Y Color General Mura Luminance Mura Evaluation Value Color Mura Evaluation Value Observers: 40 persons (male x 20, female x20) Mura evaluation pattern: 45 patterns R 2 : 0.93 Verification test Observers: 50 persons (male x 25, female x25) Mura evaluation pattern: 45 patterns R 2 : 0.95 International conference presentation IDW 11: VHF4-1 Quantitative Evaluation Method for Luminance and Color Uniformity of a Display Screen Based on Human Perceptions

16 Examples of Evaluation Result Example of Mura Images Luminance Edge Luminance Mura Area Chroma Edge Color Mura Area

17 Examples of How Mura Evaluation Value is used ITU-R Case 1 Case 2 Case 3 5 0~5 0~3 0~1 4 ~10 ~6 ~2 3 ~15 ~9 ~3 2 ~20 ~12 ~4 1 ~25 ~15 ~5 Device TV Monitor Monitor for Medical Signal Input Level 20% 50% 100% 20% 50% 100% 20% 50% 100%

18 Summary Quantitative evaluation method of mura The equation of Luminance Mura evaluation Y Lum = 1.90 X a X b X c X a : Luminance mura area X c : Luminance edge area The equation of Color Mura evaluation X b : Maximum luminance difference Y Color = 3.97 X d X e X f X d : Color mura area X e : Maximum chroma X f : Chroma edge area The equation of General Mura evaluation Y Gen = Y Lum Y Color Y Lum : Luminance mura evaluation value Y color : Color mura evaluation value

19 List of International Conference Presentation IDW 08:VHFp-5 Subjective Evaluation for Indistinct Mura of LED backlight IDW 09:VHFp-15 A Quantitative Evaluation Method for Indistinct Mura of LED Backlight SID 2010:Applied Vision P-48 Quantitative Evaluation Method for the White Uniformity of a Large-Sized LED Backlight IDW 10:VHF 1-5L Influence of Multi-colored Unevenness on White Uniformity Evaluation of an LED Backlight EuroDisplay 2011: Session 10-3 Quantitative Evaluation Method for Color Uniformity of a Display Screen Based on Human Perceptions IDW 11: VHF4-1 Quantitative Evaluation Method for Luminance and Color Uniformity of a Display Screen Based on Human Perceptions IDW 12: VHF9-4L A Quantitative Mura Evaluation Method that Depends on Viewing Distance

20 Sony はソニー株式会社の商標です 各ソニー製品の商品名 サービス名はソニー株式会社またはグループ各社の登録商標です その他の製品および会社名は 各社の商号 登録商標または商標です