Radiant Vision Systems | A Konica Minolta CompanyRadiant Vision Systems | A Konica Minolta CompanyPresented By Matt Scholz | April 3, 2018
DEFINING A SPARKLE MEASUREMENT STANDARD FOR QUALITY CONTROL OF ANTI-GLARE DISPLAYS
Global SupportAutomated Visual InspectionLight & Color
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TODAY’S AGENDA
• Anti-Glare Displays
• Background and Application
• Effect of Sparkle on Display Quality
• Measuring Sparkle: Considerations
• Creating a Standard Measurement Method
• System Specifications
• Measurement Setup
• Software Testing
• Defining Tolerances based on Human Perception
• Customer Success Story
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ANTI-GLARE DISPLAYSBACKGROUND AND EFFECT ON VISUAL DISPLAY QUALITY
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VIEWING DISPLAYS IN AMBIENT LIGHT
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VIEWING DISPLAYS IN AMBIENT LIGHT
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SOLUTION: ANTI-GLARE
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LCD with AGLCD without AG
ANTI-GLARE DISADVANTAGE
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Anti-Glare MicrostructureNuijs, Horikx, Applied Optics 33,18 (1994) p.4058
ANTI-GLARE DISADVANTAGE
LCD with AG
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ANTI-GLARE DISADVANTAGE
LCD with AG
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OPTIMIZING THE AG LAYER
Evenly-diffused Sunlight Sparkle
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MEASURING SPARKLE
• Pixel-level luminance variation calculated using standard deviation (σ) of a population
• Measured as a % deviation across a region or averaged for multiple regions (ROI)
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MEASUREMENT CONSIDERATIONSADVANTAGES FOR ACHIEVING DATA REPEATABILITY
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OBJECTIVES FOR EVALUATION
1. Effective display characterization
• Define measurement system
• Define measurement setup
• Isolate sparkle
• Reduce effects of other display anomalies
2. Evaluation based on human perception
• Perform initial human evaluation
• Correlate system measurements with human rankings
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1. EFFECTIVE DISPLAY CHARACTERIZATION
Reduce effects of display gradient
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1. EFFECTIVE DISPLAY CHARACTERIZATION
Reduce effects of display gradient
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1. EFFECTIVE DISPLAY CHARACTERIZATION
Register active display area (RADA)
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1. EFFECTIVE DISPLAY CHARACTERIZATION
Reduce other display anomalies
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1. EFFECTIVE DISPLAY CHARACTERIZATION
Color Variation (if required)
• CIE-matched tristimulus color filters
• Color calibration
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2. EVALUATION BASED ON HUMAN PERCEPTION
Define Tolerance Using Several Participants
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2. EVALUATION BASED ON HUMAN PERCEPTION
Define Tolerance Using Several Participants
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2. EVALUATION BASED ON HUMAN PERCEPTION
Define Tolerance Case by Case
Customer A Suppliers X, Y, Z
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CREATING A STANDARD METHODHOW TO ACHIEVE REPEATABLE SPARKLE MEASUREMENT FOR AG DISPLAYS
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SYSTEM SPECIFICATIONS
• ProMetric® Camera:
• I-series imaging colorimeter
• Y-series imaging photometer
• High resolution (to 29MP)
• 61 dB dynamic range
• Per pixel, 1x1 binning
• Thermoelectrically-cooled sensors
• High SNR
• Factory calibration
• 50mm electronically-controlled lens
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SYSTEM SPECIFICATIONS
• TrueTest™ Software
• Data acquisition & analysis
• Test sequencing
• RADA
• Gradient filter
• Blob removal
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HOW TO SET UP THE MEASUREMENT
1. To ensure stability, use breadboard and lock down the display
and camera.
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HOW TO SET UP THE MEASUREMENT
2. Measure to the location where
grey meets black on both sides
of the camera (CCD plane).
CCD Plane
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HOW TO SET UP THE MEASUREMENT
3. The distance from side to side should be equal to ensure the
camera and the display are parallel.
CCD Plane
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HOW TO SET UP THE MEASUREMENT
4. Measure using the offset of physical to focus distance from the
screen to the CCD plane of the camera.
CCD Plane
0.5m
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HOW TO SET UP THE MEASUREMENT
< 0.1 mm
< 0.1 mm
< 0.5°
< 0.5°< 0.5°
5. Check Alignment of the Display
• The display must be centered at the camera’s optical axis, with no rotation or tilt
- x < 0.1 mm / y < 0.1 mm
- Axial rotation < 0.5° / Horizontal tilt < 0.5° / Vertical tilt < 0.5°
• Display orientation is measured by the software
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SPARKLE ALIGNMENT
Example Application:Software alignment window refreshing the angular & offset measurement by localizing the 5 dots
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HOW TO SET UP THE MEASUREMENT
6. Double-check Focus Mode in software to ensure you are
centered in the display.
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0.5m
CCD Plane
HOW TO SET UP THE MEASUREMENT
7. Set the display to green.
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HOW TO SET UP THE MEASUREMENT
8. Ensure all ambient light is removed.
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HOW TO SET UP THE MEASUREMENT
9. Using the Sparkle Measurement Setup in software, take a
measurement and record the value.
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HOW TO SET UP THE MEASUREMENT
10. Adjust the exposure for the Y filter in software.
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TAKING A MEASUREMENT
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TAKING A MEASUREMENT
Using the Subframe Tool in software, create a subframe of
500x500 pixels located at the center of the display.
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TAKING A MEASUREMENT
Analysis AreaSub frame
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SOFTWARE TEST
TrueTest Random Mura Algorithm
• Standard deviation of a population – Avg for all ROI
7 8 9
4 5 6
1 2 3
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SOFTWARE TEST
TrueTest Random Mura Algorithm
• Standard deviation of a population – Avg for all ROI
7 8 9
4 5 6
1 2 3
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SOFTWARE TEST
TrueTest Random Mura Algorithm
• Standard deviation of a population – Avg for all ROI
AVG%
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DEFINING ACCEPTABLE TOLERANCES
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1 2 3 4 5 6 7 8 9 10
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7 8
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DEFINING ACCEPTABLE TOLERANCES
Ran
kin
g
Human Observers
Display A
Human Ranking 10 (best) ≈ Measured Sparkle Value 1.36%
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DEFINING ACCEPTABLE TOLERANCES
Ran
kin
g
Human Observers
1 2 3 4 5 6 7 8 9 10
Display B
Human Ranking 7 (acceptable) ≈ Measured Sparkle Value 2.21%
1
2
3
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5
6
7 8
9
10
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DEFINING ACCEPTABLE TOLERANCES
Ran
kin
g
Human Observers
1 2 3 4 5 6 7 8 9 10
Display C
Human Ranking 6 (poor) ≈ Measured Sparkle Value 3.05%
1
2
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7 8
9
10
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DEFINING ACCEPTABLE TOLERANCES
Ran
kin
g
Human Observers
1 2 3 4 5 6 7 8 9 10
Display C
Human Ranking 6 (poor) ≈ Measured Sparkle Value 3.05%
1
2
3
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5
6
7 8
9
10
Acceptable tolerance 2.21%
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MEASUREMENT RESULTSCAMERA-TO-CAMERA & CAMERA-TO-HUMAN REPEATABILITY
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RADIANT DISPLAY TESTING
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SYSTEM USED 1 2 3 4 5 6 7 8 9 10 AVG
I16 .5M DISPLAY C
500X500 SN 31523.624 3.618 3.611 3.613 3.616 3.613 3.606 3.607 3.613 3.6 3.6121
I16 .5M DISPLAY B
500X500 SN 31522.87 2.854 2.871 2.83 2.86 2.808 2.756 2.843 2.809 2.878 2.8379
I16 .5M DISPLAY A
500X500 SN 31522.472 2.469 2.474 2.453 2.475 2.45 2.47 2.469 2.474 2.468 2.4674
1 2 3 4 5 6 7 8 9 10 AVG
I16 .5M DISPLAY C
500X500 SN 5553.652 3.691 3.686 3.692 3.68 3.684 3.679 3.69 3.696 3.681 3.6831
I16 .5M DISPLAY B
500X500 SN 5552.973 2.971 2.964 2.968 2.975 2.967 2.984 2.968 2.971 2.975 2.9716
I16 .5M DISPLAY A
500X500 SN 5552.57 2.563 2.563 2.57 2.561 2.563 2.585 2.578 2.588 2.588 2.5729
SYSTEM REPEATABILITY
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SYSTEM REPEATABILITY
DUT% diff Camera to
Camera
Display A 1.95%
Display B 4.60%
Display C 4.19%
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Camera To CCD Plane (m) Focus Distance (m) Display C
I29 0.483 0.5 3.424
I16 0.483 0.5 3.417
I8 0.483 0.5 3.48
I2 0.483 0.5 3.452
RESOLUTION REPEATABILITY
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SPARKLE MEASUREMENT RESULTS
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SPARKLE MEASUREMENT RESULTS
Maximum Pixel Variation %for a single display
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CUSTOMER SUCCESS STORYSPARKLE MEASUREMENT CORRELATED TO HUMAN VISUAL PERCEPTION
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SUPPLIER IQC/OQC STANDARDS
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SPARKLE IN SUPPLIER DISPLAYS
Without AG layer With AG layer
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0
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10
0 1 2 3 4 5 6 7 8 9 10
Hum
an R
ating
Radiant Camera (Sparkle) Rating
SPARKLE/HUMAN CORRELATION
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DIRECTIVE FOR STANDARD MEASUREMENT
“Moving forward, all suppliers must use Radiant’s Sparkle Solution.”
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SUMMARY
✓ Anti-glare layers improve display visibility in reflective light, but
introduce sparkle, which can affect perceived quality of the display.
✓ Lack of a repeatable measurement method for sparkle has been a
barrier to defining standard quality control processes.
✓ A method employing a Radiant ProMetric imaging system, TrueTest
Software, and defined setup criteria has been proven at automotive
OEM facilities for repeatability with direct correlation to human perception.
✓ Using this method, OEMs and manufacturers of displays can set precise
tolerances for sparkle and define standards for quality control.
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