臺灣博碩士論文加值系統

本論文之研究旨在於提出一種適用於影像式色彩量測的校正方法。影像式色彩量測為以二維的影像來分析被被攝物在色度學上的表現。因為CCD攝影機最初的設計並不是用來進行光學量測，所以一定會有誤差的產生。本研究針對三刺激值來做校正，拍攝的影像以sRGB訊號輸出轉換並校正成XYZ刺激值。本文提出的校正方法，於同一位置量測三筆不同顏色的畫面來得到一校正矩陣，再拿來驗證其他顏色的畫面。
藉由觀察色座標上校正點到驗證點的距離與估算誤差的關係，實驗結果顯示，用於校正的色域面積小了16％，三刺激值量測的誤差也修正了約22％，而色座標從4％修正到1％以下。另一方面校正矩陣的趨勢變化在亮度下的表現，推算精確度的平均值也從73.7％修正到98％。
我們在本論文的研究中成功地發展出一套高準確性的二維影像色彩量測技術，可以同時量測平面光源上數個的色座標，而誤差值的控制，經由實驗驗證將可大大縮小符合可用條件。此設備若能取代目前色度量測專用檢測儀（BM7），將可降低量產之準備時程及設備成本，加上在品質控管方面結合自動化，光學取像技術及圖像識別的演算等，在效益上將會提升國內檢驗業者在國際市場的競爭力。

This thesis proposes a calibration method for two-dimension optical measurement. Two-dimension image of color measurement has great potential for the analysis about chromaticity on the panel of a display. The original design purpose of CCD camera is for imaging but not for precise optical measurement. There exist some difference between the standard RGB spectrum definition and the CCD imaging system. This thesis proposes a calibration method which focuses on the analysis of tristimulus of CCD signals. The output image data with sRGB signal will be transformed and a calibration matrix to XYZ tristimulus is built. By measuring three different color frames the calibration matrix is calculated and then we go to verify our proposed algorithm by the testing measurements of other colors.
By observing the estimation errors from the verification and the distance between the calibration points and the verification points, it can be realized that the shorter distance obtains smaller error. Finally, we get results that errors of the estimation of the tristimulus in 16% narrower region on CIELUV chromaticity coordinate are reduced almost 22% than the original experiment and the errors of CIELUV coordinate are from 4% to 1%. On the trends of the calibration matrix with brightness, the average accuracy is from 73% to 98%.
We have successfully developed a high accuracy of color measurement with two-dimension imaging technology. In single measurement, one could get the chromaticity coordinate for each position on the flat panel. By the experiment, we prove that the error can be controlled as small as practical. If the system could take the place of BM7 as chromaticity measurement, it would lower the developing time and the instrument cost. Besides, to combine automations, imaging technology and image identification will grow the competitive ability of domestic instruments technology.

摘要 I
Abstract II
誌謝 IV
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Organization 3
Chapter 2 Color Vision and Colorimetry Theory 5
2.1 Radiometry and photometry 5
2.2 Tristimulus values R, G, and B 9
2.3 Tristimulus values X, Y, and Z 11
2.4 The CIE xy chromaticity diagram 12
2-5 Gamma Correction 15
2.6 sRGB Signal 17
Chapter 3 Color Imaging Process 18
3.1 Signal Grabbing 20
3.2 Image Division and Average 20
3.3 Chromaticity Transformation and Calibration 21
3.4 Procedures for Calculation of Calibration Matrix 24
3.6 Imager with CCD Camera and Color Analyzer 25
3.6.1 CCD Camera Device 26
3.6.2 Color Analyzer 28
Chapter 4 Image Techniques for Chromaticity Analysis 32
4.1 Picture Function 32
4.2 Image Division and Average 35
4.3 Sub-Pixel Array Average 40
4.3 Repeatability and Reproducibility Test to Devices 41
4.4 Chroma Color Analyzer Measurement 44
4.5 Calibration with Wide Region of Chromaticity Coordinate 46
4.6 Verification Errors in Chromaticity Coordinate 49
4.7 Verification in Narrow Region 54
Chapter 5 Gluing Light Source and Light Guide for Small Size Module 56
5.1 Abstract 56
5.2 Background 57
5.3 Construction of LED backlight module 58
5.3.1 Two types of light guides 58
5.3.2 Transparent Glue 59
5.3.3 LED Light Source 59
5.4 Result of Optic Simulation 65
5.5 Summary 67
Chapter 6 Conclusions 68
References 70
Publication List 72
LIST
OF FIGURES
Figure 1.1. Two ways of colorimetric measurement for flat surface 4
Figure 2.1. Color-matching fields with a polychromatice reference field 10
Figure 2.2. Chromaticity x – y diagram for a 10-deg (CIE 1964) 13
Figure 2.3. Hue and saturation variation in the chromaticity diagram 14
Figure 2.4. Dominant and complementary wavelengths in the chromaticity diagram 15
Figure 2.5. The scale of Vs is an encoded scale with gamma of 2.2;and I is an linear-intensity scale 16
Figure 3.1. Tree branches in colorimetric measuring system 19
Figure 3.2. Dividing and averaging to color image 21
Figure 3.3. Flowchart of calculation with transformation and calibration 23
Figure 3.4. CCD camera Basler A312fc 27
Figure 3.5. Basler A312fc spectral response 27
Figure 3.6. CCD camera measuring distance 28
Figure 3.7. System diagram of Chroma 7121 display color analyzer 29
Figure 3.8. The part of optical table touching the sample with a sensing probe of color analyzer 31
Figure 4.1. Operating interface of control program 34
Figure 4.2. Flowchart of program functions 37
Figure 4.3. Flowchart of numerous image averages 38
Figure 4.4. Steps of division, center selection, and individual arrays of R, G, and B 39
Figure 4.5. Array average for measuring area to a pixel 40
Figure 4.6. The part of optical table touching the sample with a sensing probe of color analyzer 45
Figure 4.7. Positions of wide gamut for calibration matrix M 48
Figure 4.8. Nine elements in each k and their trend lines in wide gamut experiment 48
Figure 4.9. Nine elements in each k and their trend lines for error analysis experiment 50
Figure 4.10. Points with errors in CIELUV chromaticity coordinate for error analysis in k = 0.7 51
Figure 4.11. Points with errors in CIELUV chromaticity coordinate for error analysis in k = 0.5 52
Figure 4.12. Points with errors in CIELUV chromaticity coordinate for error analysis in k = 0.5 55
Figure 5.1. The situation of ray traveling from LED into light guide 58
Figure 5.2. Structure of light guide (unit: mm) 60
Figure 5.3. Patterns within the light guide 60
Figure 5.4. The prototype with light sources and light guide 61
Figure 5.5. The cave type of light guide and LEDs 62
Figure 5.6. Placement of LEDs in light-couple face (unit: mm) 63
Figure 5.7. Angular Intensity Distribution (OSRAM LHR-974) 63
Figure 5.8. Prototype of backlight module with glue 64
Figure 5.9. Entire LED immersed in the glue of cave light guide 64
Figure 5.10. Luminance vs. Refraction 66
Figure 5.11. Error estimate at peak vs. Refraction 66
LIST OF TABLES
Table 2.1. Comparison of radiometry and photometry quantities 8
Table 3.1. Specifications of CCD camera 26
Table 3.2. Specifications of display color analyzer 30
Table 4.1. Repetition testing for CCD camera on red frame 42
Table 4.2. Repetition testing for CCD camera on green frame 42
Table 4.3. Repetition testing for CCD camera on blue frame 43
Table 4.4. Repetition testing for Chroma color analyzer on white frame 43
Table 4.5. Measurants of unofficial measurement which a distance between probe and testing surface 45
Table 4.6. Estimations of the tristimulus values with various k at the position W 47
Table 4.7. Estimations of the coordinate on CIELUV with various k at the position W 47
Table 4.8. Estimations of tristimulus values in wide region with k = 0.7 51
Table 4.9. Estimations of the chromaticity coordinate in wide region with k = 0.5 52
Table 4.10. Estimations of tristimulus values in wide region with k = 0.5 53
Table 4.11. Estimations of the chromaticity coordinate in wide region with k = 0.5 53
Table 4.12. Estimations of tristimulus values in narrow region 54
Table 4.13. Estimations of the chromaticity coordinate in narrow region 54
Table 5.1. The simulation results with prototype light guide 65
Table 5.2. The simulation results with cave type light guide 65

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