JONATHAN Brawn Principal, Brawn Consulting Director, Digital Signage Experts Group Director, Imaging Science Foundation Commercial
Projected Growth! • Pacific Media reports that the sale of projectors is increasing at 13% year over year, and forecasts that this will continue in the near term. • The Digital Signage Federation reports that 25%-30% of digital signage utilizes projection of one type or another. • Advances in technologies such as liquid crystal on silicon have stoked interest in projection.
A Long Time Ago…… • Projection of an image using a light source actually goes all the way back to the 1700s, but in modern times it began with the projection of film, and in 2011 it has come full circle.
Projection Selection: Ready-Set-Stop • Before we begin to delve into the technical analysis of projectors for a given application, we must start with a needs analysis, interacting with the customer to establish the parameters under which the selection will reside. We must explore the following: • Objective/purpose of the system and how the projector selected will meet those needs. • Environment/space/orientationof the room including size, shape, obstacles, and any impediments that might affect the system. • Ambient lightis a “necessary evil” but in all cases it decreases the quality of the image on the screen. We need to examine where it comes from, quantify it, and see how we can control it. • Audiencesize and position. • Content to be displayed is important in terms of type, legibility, and quality required. • Service of the projector relates to accessibility, frequency/quantity, and availability of spare parts tied into MTBF estimates. • TCO relates to an analysis of the cost of the projector, serviceability, and how long the projector is expected to last before replacement.
Categories: Pico Projectors • A Pico or pocket projectoris an emerging technology in the world of a handheld devices. • Handheld projectors involve miniaturized hardware and software that can project digital images onto any nearby viewing surface, such as a wall. • These units will often weigh less than a pound, and typically offer a built in battery. • Some even provide a built in media player. • Generally less than 50 lumens of light output.
Categories: Micro/Mini Portables • This projector category is slightly larger than a Pico Projector and in terms of order of magnitude a “lot” brighter. • Micro Portables weigh from a pound to just over 2 pounds and will fit in the palm of your hand. • They feature light output from 50 Lumens up to 200 Lumens. • They can project up to a 100” diagonal image in a dark room. • Do not forget that this was in the range of the light output of the original CRT projectors!
Categories: Ultra Portable Projectors • This category of projectors is all about portability for multiple uses in office, schools and road warriors at under 4 pounds in weight and some as light as 2.4 pounds! • They feature 2k or greater light output and most include HDMI, VGA, s-video, composite video and USB. • Many include models that are available in XGA and WXGA resolution for both 4:3 and 16:10 aspect ratios. • Examples: • Optoma EW330 at 2.4 Lbs (2200L) • Epson PowerLite 1730W at 3.74 Lbs (3000L) • Hitachi CPX5 at 3.8 Lbs (2500L)
Categories: Portable Projectors <10 Lbs • The next step up the projection chain is still portable but might weigh as “much as” 10 pounds but the majority fall in the 7 to 8 Lb range. • They are brighter, provide better contrast and in most cases a better overall picture experience mostly due to optical design and more advanced processor circuitry. • They also feature longer zoom lens ranges than the typical ultra portable. • Many in this class provide networking capability as well. • Examples: • Epson PowerLite 1915W 7.82 lbs. (4000L) • Hitachi CP-WX410 7.7 lbs. (3000L) • Optoma TX762 at 6.4 lbs. (4000L)
Categories: Installation Projectors • Installation projectors are as the name implies intended for permanent system installation. • In this regard they are not constrained by size, weight, limited optics, or other impediments to image quality and performance. • This category focuses on the larger, brighter and more feature laden projectors on the market. Although today, many companies find that smaller, "portable" projectors are more than adequate for installation in training, board and conference rooms, there is still large demand for the brightest and the best. • Here we look at projectors, typically over 12 pounds, (and up to a couple hundred pounds), that may offer interchangeable lenses, and typically offer brightness from 3000 to 15,000+ lumens.
Categories: Large Venue Projectors • Large venue projectors are at the top of the performance tree. They are used for large auditoriums, conference centers, high ambient light situations, and for large screens requiring the light output fro impact of the image. They are also use predominantly for rental and staging applications. • They provide light output from 10K lumens up to nearly 35K Lumens! • They feature interchangeable lenses, electronic lens shift, and in most cases dual lamp capabilities. • The big guys may also include built in warp engines and edge blending processors. • The construction is strictly heavy duty and many are available with rigging fixtures for ease of flying and handling in rental and staging applications.
Categories: Specialty Projectors • Specialty projectors due not fit a single category although they may have elements in common with other types. • Short throw projectors • All in one projectors • Simulation projectors • Others
Categories: Home Theater Projectors • Home theater projectors are closely related to cinema projectors in that they are designed with the attainment of the best video image possible in mind. • Today's models are true HD capable at 720P or 1080P resolution • They are high performance single chip DLP or three chip LCD, or LCoS with some higher end models using 3 chip DLP. • They feature better optics, higher performance processing “engines”, lens shift, and in some cases auto iris designs. • They are also typically lower light output below 2K lumens since they will be used in controlled light environments which also permits higher contrast. • After the installation, calibration is an important part of home theater projection
Categories: Cinema Projectors • Digital Cinema projectors are a special class of projector that meet specific standards dictated by the Digital Cinema Initiative (DCI) • DCI calls for digital cinema projectors to have a resolution of 2K (2048×1080) or 4K (4096×2160) . • Most digital cinema projectors are 3 chip DLP based. • Three main manufacturers provide these projectors, and as of 2010 there are over 6K units with 80% in North America: • Christie Digital • Barco • NEC • Another technology by Sony called "SXRD" is a type of LCoS. They offer 4096x2160 (4K) resolution. These projectors suffer from low yield, and are not commonly available.
Where Canon fits Large Venue Models High resolution (HD/WUXGA) WUX4000 7000lm or more Installation Models High resolution (HD/WUXGA) Weight 5kg or more SX Series Portable Models High resolution (SXGA+/WUXGA) Medium resolution (XGA/WXGA) LV Series
The Effect of Display Specifications • In most audiovisual systems design, the display is the key component in the room. With this in mind, it is a requirement to match the display to the environment, and to the explicit needs set forth in the sales proposal. • It is necessary to understand the specifications relating to display technologies, in order to properly design for individual applications. The key considerations are: • Brightness • Contrast • Color Reproduction
Brightness Defined • Brightness is the measurement of light falling on a surface, or light emitting from a source. It is most commonly measured in two units, when relating to display technologies: • Lumens • A lumen is a measurement of light falling on a surface, such as a projector illuminating a screen. • A lumen is equal to one foot-candle falling on one square foot of area. • Properly specified, they are referred to as ANSI lumens, which infers adherence to the American National Standards Institute method of measurement. Note: The original ANSI Standard is no longer a recognized reference. • This is essentially a measurement of projector horsepower, and is not what we actually see when we look at a screen. Light Falling on Screen
Brightness Defined • When dealing with projectors, the lumen measurement is not actually what we see. What we see when we look at the screen, is reflectedlight, measured in the following units: • Foot Lamberts: The luminance (brightness) resulting from a surface emitting a luminance flux of one lumen per square foot. The luminance of a perfectly reflecting surface receiving an illumination of one foot candle. Foot Lamberts are measured as reflected light off the screen. This is the specification that we actually see when looking at a screen. • Foot Candle: The illumination from one candle at a distance of one foot. Equal to one lumen incident to one square foot. This specification and measurement applies to ambient light in an environment. Light Falling on Screen Light Reflected from Screen
Brightness Defined • Types of Light Meters • There are two kinds of light meters in common use. • Spot Photometers or Spot Meters are used to measure a targeted area’s illumination, such as measuring screen brightness. They have a designated angle of acceptance, stated in degrees, showing how wide an area they measure. The ANSI specification for a spot meter requires a 2° or less measurement area. • Incident Light Meters are used to measure light falling on the meter. They will have a white sphere that allows them to accept light over a wide angle. Incident meters are used to measure ambient light.
Brightness Defined • Measuring Projector Brightness 3 2 1 6 4 5 7 8 9 ANSI lumens are measured across a 9 zone average, using a 2° or less Spot Photometer (Light Meter)
Contrast Defined • Contrast is a measure of an image, defined as the ratio of the luminosity of the brightest value (white) to that of the darkest value (black). • Contrast is stated as the ratio between maximum and the minimum brightness values. e.g. 100:1 • In digital technologies, contrast is the difference between the luminance or brightness of an ON pixel and that of an OFF pixel. • Note: In real world applications, the way we perceive contrast is a function of the display, seating, ambient light, content, and even the color of the viewing environment. Luminance for ON Pixel Luminance for OFF Pixel Off Pixel On Pixel Contrast Ratio =
Contrast Defined • Low Contrast Image High Contrast Image • Note: Contrast is the element of a picture on a display that most notably drives the perception of quality in a picture, i.e. increased depth of field and the appearance of more details.
Contrast Defined • Full On/Off Contrast • This measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. This is the measurement most favored by manufactures as it yields a larger number for the contrast ratio - typically 25% or more - than ANSI contrast measurements for the same display device. • ANSI Contrast • This is measured with a pattern of 16 alternating black and white rectangles - also referred to as the 'checkerboard' test pattern. • The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. • ANSI contrast represents a more fair way to test contrast ratio as the presence of black and white at the same time is closer to the real world environment rather than the all black or all white image used during the full ON/OFF contrast measurement. • This renders the average reading obtained from the ANSI contrast more realistic. A 2° Spot Photometer is used for these measurements.
Contrast Defined • Full On / Full Off Contrast Measurement
Contrast Defined • ANSI 16 Zone Contrast Measurement
Contrast Defined • Grayscale: • One cannot talk about displays without mentioning something on the grayscale performance of a display or video projector. • An analog grayscale is a smooth ramp of values going from completely black at one end, to completely white at the other. • The truth is that while contrast is an important attribute, it alone does not provide useful picture information - only grayscales do. • It is the gray-scaling performance of an imaging device that is the single most important attribute to consider. This is dictated by the processor in the display. A higher bit depth processor allows for more “steps” in the grayscale. • A larger number of grayscales would imply a device greater ability to display subtle detail in dark or bright scenes. • It is also this element that enables a display to create a wide color palette. Without shades of gray, contrast alone is of no use in delivering image detail.
New ANSI Contrast Ratio Standard • ANSI/InfoComm 311M – Projected Image System Contrast Ratio (PISCR) • Informational Viewing (7:1) • The viewer is able to recognize what the images are on a screen and can separate the text or the main image from the background under typical lighting for the viewing environment. There is passive engagement with the content (e.g., casual television viewing). • Basic Decision Making (15:1) • The viewer can make decisions from the displayed image. The decisions are not dependent on critical details within the image. The viewer is actively engaged with the content (e.g., photos, typical informational presentations, public transportation informational displays). • Critical Decision Making (50:1) • The viewer can make decisions from the displayed image based on critical details within the image. The viewer is fully engaged with these details of the content (e.g., architectural/engineering drawings, legal evidence, medical imaging and photography). • Full Motion Video (80:1) • The viewer is able to discern key elements present in the full motion video, including detail provided by the cinematographer or videographer necessary to support their story line and intent (e.g., home theatre).
Display Color • When dealing with a display, another important specification is it’s color reproduction. • Color reproduction is the ability of a display device to reproduce a range of colors that will meet, or exceed, the range of colors needed by the intended content to be shown on that display. • Display color reproduction relates to 4 specific terms that define how a display produces color, and in what amounts: • Primary color • Colorspace • White reproduction or color temperature • Gamut
Display Color • What is color? • Color is a perceived property of light. • Light is essentially a wave of electromagnetic energy, measured in nanometers (nm), that falls within the range of frequencies perceived by the human eye. • Different wavelengths of light are perceived as different hues, that we define as colors. • The main color “categories” we recognize are red, orange, yellow, green, blue, indigo, and violet. • White and black are not true colors, but really the presence of ALL wavelengths of light (white) or absence of all wavelengths of light (black).
Display Color • How does display color work? • Display devices, whether flat panel or projection, and regardless of technology, all use the additive mixing process to produce color. • Additive mixing is the combination of wavelengths of light to produce colors, based on the use of reflected light. Printed or dyed materials use subtractive mixing, or the absorption of wavelengths of light, to produce color. • A display device will achieve this by establishing 3 fixed hues, or colors, of light, called primary colors, and combining them together in various amounts to create other colors, and in equal amounts to create white. • The three primary colors used by the display industry are red, green, and blue.
Display Color • Understanding Colorspace • The chart shown to the right is the CIE Chromaticity Diagram. This chart displays all of the colors that make up the range of human vision, and provides us with a way to measure, chart, and understand how a specific color, or range of color, fits into our sight. • No display device produced today can replicate all of the wavelengths of light that make up human vision, and no content produced today requires the entirety of the area shown. However, content will frequently be produced with a range of colors in mind, known as a colorspace. • A colorspace is a group of three sets of coordinates, corresponding to three primary colors shown on the CIE Chromaticity Diagram. There will be lines drawn on the diagram, to define a triangle. This triangle now contains the range of colors that make up that colorspace. • Different types of content can require a display to be capable of producing a specific colorspace, and either meeting, or exceeding the range of colors that make up that colorspace.
Display Color • What is color temperature? • Color temperature, sometimes called white balance, is a metric by which we can relate how a display is configured to reproduce white, and how warm (reddish) or cool (bluish) it will be. • Color temperature is measured based on the scientific measurement of heat, called Kelvin. The more Kelvin, the cooler, or more blue, the white will be. The less Kelvin, the warmer, or more red, the white will be. • The ideal standard for color temperature, based on standards from the Society of Motion Picture and Television Engineers (SMPTE) and the Digital Cinema Initiative (DCI) is 6500 Kelvin, which relates to optimal sunlight. • Proper reproduction of white is required to display content correctly, so the display’s calibration of color temperature should be set to match what the content is developed for.
Display Color • Display Gamut • A display’s ability to reproduce color is known as it’s gamut. A gamut is essentially the colorspace a display is capable of producing. • This will commonly be shown as a triangle, drawn over a simplified CIE Chromaticity Diagram. • A display’s color gamut can also be related as a percentage of a specific colorspace, such as “98% of NTSC”, or “108% of REC709”. • It is important to ensure that a display device of any type is capable of producing a gamut covering as much of the colorspace required by the intended application as possible, or to even produce a greater gamut than required, in order to properly render the content.
Display Resolution • In digital displays, resolution is the number of pixels (individual picture elements) contained on a display, expressed in terms of the number of pixels on the horizontal axis and the number of pixels on the vertical axis. e.g. 1920x1080 • The sharpness of the image on a display depends on the resolution and the size of the display. The same pixel resolution will be sharper on a smaller display and gradually lose sharpness on larger display because the same number of pixels are being spread out over a larger number of inches. 1366x768 1920x1080 1024x768
Signal Formats • Aspect Ratios • What is an aspect ratio? Aspect ratio is typically described as the ratio of screen width to screen height. • There are two common aspect ratios, the first is that of a standard television which has a 4:3 (referred to as "4 by 3") aspect ratio. Also note that the television aspect ratio is listed as 1.33:1. This is another way of listing aspect ratios—dividing the width by the height (e.g., 4/3 = 1.33). This is referred to as "1.33:1" or "1.33 to 1". A widescreen display, such as a plasma or LCD panel, will usually have a 16 by 9 aspect ratio (16:9). Since 16/9= 1.78, the aspect ratio is also known as "1.78:1" or "1.78 to 1".
Scaling – Making it fit! • By definition, a digital display can also be referred to as a fixed matrix display, with a finite number of horizontal and vertical picture elements, or pixels. e.g. 1024x768 • In many instances the resolution of the video signal, and the physical resolution of the display do not match. The “mismatch” requires what is known as scaling. • Scaling refers to a process of taking a higher resolution signal, and modifying it to be displayed on a lower resolution device, or a lower resolution signal, and modifying it to be displayed on a higher resolution device. • This process is a complicated mathematical algorithm that analyzes the video signal and performs the adaptation of the resolution. 800x600 ¹ 1024x768 ¹ 1280x1024
Scaling Algorithm • A fundamental understanding of the way basic scaling works is illustrated below. Take 2 adjacent pixels of the signal and divide by 2 Signal Resolution 800x600 Scaling is an interpretation or interpolation of a lower resolution or higher resolution signal into a native resolution chip Native Resolution 1024x768 Take 2 adjacent pixels and add together Signal Resolution 1280x1024
LCD Construction Principle • To create an LCD, you take two pieces of glass with polarizing films applied, which are assembled together with a carefully controlled gap between. • When liquid crystal material is introduced to this cell, the layers adjacent to the glass will align, resulting in a helical structure of molecules between the two glass plates. • As light strikes the first plate, it is polarized. • The molecules in each layer then guide the light through the display, changing the angle of polarization to match.
LCD Construction Principle • When light reaches the final layer of the crystal material its plane of polarization will have been rotated through 90 degrees and since the plane of polarization matches the plane of the polarizing film, light will be transmitted. • If we apply an electric field to liquid crystal molecules, they untwist. • When they straighten out, they change the angle of the light passing through them so that it no longer matches the angle of the top polarizing filter. • Consequently, no light can pass through that area of the LCD, which makes that area darker than the surrounding areas.
LCD Addressing Data Lines Address Lines Pixel
LCD Color Production • LCD projectors utilize three LCD panels or chips as the imaging devices, one for each of the primary colors. The lamp approximates pure white light from which the colors of the spectrum can be extrapolated.