Παρακάτω τα απαραίτητα στοιχεία για σωστή προβολή hdr μέσω προβολέων με τις σημερινές δυνατότητες από έκθεση τεχνικών της sim2. Αναφέρει ως προυπόθεση τη χρήση δυο προβολέων, ενός βελτιστοποιημένου για τις σκοτεινές σκηνές και ενός για τις φωτεινές, συν εξωτερικού επεξεργαστή εικόνας. Το κόστος βέβαια στο θεό!
Human Vision vs Actual Luminance Range
Luminance Dynamic Range
Dynamic Range = Max Light Intensity / Min Light Intensity
• 10 f-stops=210:1=1024:1 contrast ratio
• 14 f-stops=214:1=16.384:1 contrast ratio
• 16 f-stops=216:1=65.536:1 contrast ratio
100.000:1 is normally regarded as the range that the human eye can see in a scene with no adaptation
• Standard Dynamic Range (SDR) is ≤ 10 f-stops
• Enhanced Dynamic Range (EDR) is > 10 f-stops and < 16 f-stops
• High Dynamic Range (HDR) is ≥ 16 f-stops
However, there is still no agreed definition of EDR and HDR in terms of f-stops or other metrics.
The Max luminance value
• Dynamic Range is not enough for reproducing the luminance of the REAL WORLD
• It’s needed to add the Max luminance value.
• The video community considers 10.000 cd/m2 as a good Max Luminance value for reproduction of a display
• SIM2 considers the combination of these two factors, as targets of a real world image reproduction:
- Luminance Dynamic Range: ≥ 16 f-stops
- Max Luminance Level: ≥ 10.000 cd/m2
SIM2 HDR47 MONITOR : THE 10 STEP
• Panel Type: 47” LCD TFT, High Temperature
• Resolution: 1920 x 1080 Full HD, 60 Hz
• B..LU. LED Density: 2202 Power LEDs, Hexagonal Pattern
• Dynamic Range: >17,5 f-stops
• Brightness: >6000 cd/m2 @ 15%-50% panel area >2500 cd/m2@ full white, ANSI 9 points
• Color Gamut: REC709
• White Point: 6500°K (5000-9000°K adjustable)
• Brightness Uniformity: +/- 10% (90%), ANSI 9 points
• HDR Video Coding: Agnostic, Independent
The case of Video Projection
• In case of video projection, in place of luminance (nits), illuminance (lux) has to be considered, that is the luminous power incident on a surface.
•There isn’t a standard for HDR projection displays yet
• By applying the same method to the case of projection displays, SIM2 considers the following target values for a real HDR projection:
Dynamic Range: ≥ 16 f-stops
Max illuminance Value: ≥ 70 fL or 240 lx
• Note that Digital Cinema Min Illuminance Value is: ≥ 14 fL or 48 lx
SIM2 research for an HDR solution
•Looking for an expansion of the dynamic range, many solutions have been simulated and tested in the laboratory.
•These solutions were sought for elevating the flow of light and the contrast at the same time.
Among these are the following:
• Double UHP lamp
• HDR DMD
• Static Iris
• Dynamic Iris
• Antireflective high performance coatings • Lens Buffles
• Optical Masks
SIM2 Projection platform used: the Lumis
• Technology: DLP, 3-chips, 0.95”, DC4
• Image Resolution: 1920x1080, Full HD
• Light Source: UHP Lamp, 350W, 0.9mm arc gap
• Peak Luminous Power: 5000 lm
• Ansi Contrast: 400:1 C.R.
• Colour Gamut: REC709 or DCI P3
• Dynamic Contrast: dynamic aperture@frame speed
• Dimensions: extremely compact (SIM2 Alpha Path R )
• REC 709 and DCI P3 color gamut selection, through motorized filters within the light engine
High Contrast solutions in the Lumis
A list of solutions has been taken in order to guarantee the highest contrast possible:
Some of them are the following:
• 3 x DarkChipR4 0.95” DMDs, the best for high contrast purposes • Masks for stray light control
• Stop Iris in the illumination path
• Wide angle coatings on 3 colors splitting and recombining prism • Treatments for reduction of the ghosts and halos in prism
• Baffles on Projection lens
• High Purity Lens glasses
• Well shaped Cat Eye Stop Masks
• Black paint of barrel and lenses rims
A well balanced dynamic aperture
• SIM2 developed a well balanced dynamic aperture, through optical simulations and lab tests of various blade materials and shapes.
•It permits to visualize small gray level details even in low brightness images.
• The Dynamic BlackR (TI)video processing has been applied.
• A lot of tests has been performed in order to get the best results in every video conditions, always free from artifacts.
• The thermal management required special attention for assuring a long life to the voice coil actuator.
ONE PROJECTOR IS NOT ENOUGH
• To obtain an high illuminance value, a powerful projector is needed, with a low f# and a fast lens.
• Instead, to obtain a low black light, an high f# and slow lens are needed.
• Using a single projector only one of the above conditions is achieved.
• SIM2 has chosen a 2 projection solution, which guarantees the required peak light output, but different from each other, in optics and electronics, in order to guarantee a low black light at the same time.
• The Compact 3chips Alpha Path permits to get a
relatively compact dual projectors stack.
Two Projectors ...but different each other
Different Optics:
different peak light flow (same lamps) different contrast
different lenses (same throw ratio)
Different Electronics:
different FirmWare
different settings
The differentiation between the two projectors has the purpose to obtain that the contribution of the less bright projector to the peak brightness has a negligible contribution in the black light
Overlapping two projectors
Overlapping two projectors isn’t an easy task.
Therefore there has been developed a special mechanical platform with:
• micro mechanical adjustments
• 6 adjustment axes: x,y,z and pitch, yaw and roll
• dimensional stability against temperature
• possibility of reducing the distance between the two projectors to the minimum
• Relatively short alignment procedure
A compact duo
Furthermore:
• overlapping accuracy of 1 pixel •low warm-up time
• it has been designed a thermally stable mechanical base for both single projectors
•these design choices allow a stable behaviour towards temperature and time
Input video signal
Due to lack of HDR video material, the following configuration is used:
• FullHD BRD Player
• Commercial 1080p@24Hz BR Diskettes
• REC709 color gamut
• MPEG-4 AVC (H.264), RGB 8 bit per color • 16:9:1 and 2.40:1 format ratios
• Commercial 1in-2Out HDMI 1.4a Splitter
• Optional Video Processor with both de juddering and video splitting features BRD Splitter/ video processor
Input video signal Projector 1 Projector 2
Projectors Internal Processing
• Due to the content is coming from a standard BRD Player, the RGB color depth is 8bits color
•Full chain 10bits color depth, so the processing isn’t the bottle neck
• Fully revised de-gamma /EOTF single RGB curves
• 12 bit customized LUTs has been used
• The best results were obtained using a custom made 2.4 de-gamma curve (the same indeed exponent used in film industry)
• SMPTE ST2084 PQ EOTF selection is available as well • The system is stretching the dynamic range
•Dithering 14 bit color expansion for avoiding color banding artifacts
The Viewing Environment
• To view images and videos in HDR mode, it’s is necessary to preserve the black background.
•The demo SIM2 have been made in dark environments and with dark absorbing curtains on the walls.
•It was used a Draper screen TecVision XT1000X with unity gain, to preserve the viewing angle
•The screen sizes were: 11,3 ft wide 6,5 ft high 13,2 ft diagonal 16:9 aspect ratio
Results
Screen Area 73,6 sqft Screen Gain 1
Illuminance Measurement
Peak White 1020 lx
Black Level 0,045 lx
Max Illuminance 1020 lx
Max Luminous flux 7038 lm
Max Luminous Intensity 2241cd
Max Luminance, cd/m2 325 cd/m2
Max Luminance, fL 95 fL
A high contrast image, full of realism Public demos have been made at Cedia 2015, Dallas, and at the Winter CES 2016, Las Vegas.
CEA HDR10 media profile compatibility
• CEA defined in 2015 display compatibility specs for HDR as:
HDR 10 Media Profile SIM2 DUO HDR Projection System
EOTF: SMPTE ST 2084 —→ Available Color Sub-sampling: 4:2:0 —→ Available Bit Depth: 10 bit —→ Available
Color Primaries: ITU-R BT.2020 —→ DCI-P3, available through internal motorized filter
Metadata: SMPTE ST 2086 —→ Via RS232, through a SIM2 HDMI Conditioner (MaxFALL, MaxCLL )
• Note that UHD isn’t included in the definition. In facts, HDR feature is more related to better pixels than just more pixels
Conclusions
The Peak Luminance goals> 70 fL was reached
A dynamic Range of 14.5 f-stops was reached, quite close to the 16 f-stops target.
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