designing and specifying display systems

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Designing and Specifying Display Systems

Copyright 2012 by InfoComm International®

Visual Principles Objectives

• This seminar covers five key points: – Determining an acceptable contrast ratio– Determining acceptable ambient light level on projection

screen– Establishing actual projector brightness– Selecting projector and lens– Balancing task lighting

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System Contrast Ratio

• The light that is perceived at our eyes• Includes

– Projector– Screen material– Ambient light– Viewing task


Candle Power

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Illuminance And Luminance

• Illuminance• Light that is falling on a

surface

• Ex: light falling on a table

• Luminance• Light coming from or

transmitted through a surface

• Ex: light entering a camera


ANSI Lumen Calculation

• Meter aimed at lens• Meter readings in “lux”• Average of 9 zones• Screen dimensions in meters• Avg. lux * meters ² of screen = ANSI lumens

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System Black

• Display systems create light, they do not create dark.• The screen’s ability to reproduce black is limited to the darkness

of the screen when it is turned off • System black is defined by three parameters:

– The material of the display screen– The ambient light level– The light from the display with a solid black image input.

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• System Black


Contrast Ratio

• Measures the brightness compared with the ability to represent black simultaneously

• Measured by average readings of 8 black and white zones each

• High contrast images:– appear crisper – appear to have more

depth. – easier to read text

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System Contrast Ratio

• The light that our eyes receive• Includes the entire light path

– Projector– Screen– Ambient light


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ANSI/INFOCOMM 3M-2011

• Projected Image System Contrast Ratio• 5 viewing positions• 4 viewing tasks


Five Viewing Positions

Closest LeftClosest Left

Closest RightClosest Right

CenterCenter

Farthest LeftFarthest Left

Farthest RightFarthest Right

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Four Viewing Tasks

• Passive Viewing minimum 7:1• Basic Decision Making minimum 15:1 • Analytical Decision Making minimum 50:1 • Full Motion Video minimum 80:1


Conformance

• CONFORMS: All five measurement (viewing) locations meet or exceed

• PARTIALLY CONFORMS: One but no more than four measurement (viewing) locations falls below by less than 10%

• FAILS TO CONFORM: The contrast ratio at any one of the measured locations falls below 10%

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Calibrating With The Grey Scale Pattern

Copyright 2012 by InfoComm International®18

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Calculate Projector Brightness

Pbrightness = ((ambient light * 15 * screen area) / screen gain) / (1 – 0.XX derating)

= ((55 lux ambient light reading * 15 * 92 in x 57.5 in screen) / 1 Gain) / (1-25% derating)

Convert sq feet to meters for lumens result ( * 0.0929)

= 3743.4 lumens Round up lumens to next commercially available projector


What difference can a lens make?

Lens aperture and f-stops

Lens focal length = f-stopLens diameter

These represent full f-stops (1/2 or 2x light):

1.0 1.4 2.0 2.8 4 5.6 8 11 16 22Brighter

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Task Light Levels

• ±3x range between display brightness and task lighting levels


• This seminar covered five key points: – Determining an acceptable contrast ratio– Determining acceptable ambient light level on projection

screen– Establishing actual projector brightness– Selecting projector and lens– Balancing task lighting

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designing and specifying display systems

Technology

task copyright

camera copyright

viewing tasks copyright

available projector

lux ambient light

acceptable ambient light

task lighting levels

display screen