This article gives a small introduction to some of the individual components that make a Digital Cinema – The Digital Camera, Processing Tools, Content Distribution, Server/Theatre Management and Digital Projectors. As the name suggests, Digital Cinema aims to make all the processes completely digital using the above individual components.

In this near to digital world ruled by the 1′s and 0′s, the cinema industry has long been ruled by the Analog Film based acquisition, distribution and projection techniques. The purists have been, and still favour films to make and show their cinemas. But all that is changing fast with the introduction of Digital Cinema.

Digital Cinema is not only about digital acquisition, digital mastering, digital distribution and digital projection. Though, that’s what we will talk about in this article, Digital Cinema is more about a paradigm shift in the way in which cinema is conceived, shot, processed and shown. The concept that what ever happens in front of the camera being recorded and shown as a cinema is changing. The recorded material becomes just a small portion of what is actually shown in the screen – for example, the background setting/colour can be completely changed or even created in the PC and characters can be introduced in this new setting. Animation and special effects create an alternate reality that may not exist, but still catch the fantasies of the movie audience. Digital cinema can bring even extinct creatures before the screen and give us a perception of them being real.

The digital processing has also been happening with analog films – the video shot by the analog cameras with the films were converted in to digital data for editing, mixing, adding special effects/animations etc and then converted back to analog films for displaying them in the theatres. But now, the entire process is slowly being converted digital end to end. Let us look at the major components that make a Digital Cinema:

Digital Cameras:

Digital cameras can shoot with a resolution of 2k, 3k, 4k and some even higher! Depending on the resolution, the frame rates vary from 20 to 120 fps. Of course, the higher the resolution, lower the possible frame rates. The depth of field is usually equivalent to 35 mm cine lenses. These cameras generally contain more than 10 Mega Pixels and 4k resolution means 4520 x 2540 pixels.

There is also a video preview to enable directors to see the video shot immediately and decide if a change is required in the lighting conditions or a re-shoot is required. There is also an option for direct audio recording with attached external microphones. Digital media connectivity for direct recording is provided with the cameras via USB, HDD, Compact Flash Module, Solid State RAM etc.

The video data is sometimes compressed before transferring it to the attached external media as the storage required is as high as 20GB/min for higher resolutions. RAW data can also be recorded, if required. One striking advantage of certain digital cameras is the ability to upgrade them indefinitely by replacing the electronics/sensor units, without having to change the peripherals/accessories.

Digital Processing:

Of course, this is the heart of the digital cinema. Once the digital data is shot with the digital cameras, it is much easier to do editing, picture enhancement, colour correction, composting, visual effects, multi-format delivery etc, using digital processes. You can also mix and match formats, frame rates and resolutions much easier with digital cinemas.

Animation and special effects, no need to say, have become the mainstay of many super hit digital cinemas. Interestingly, even the digital re-mastering of classic movies shot with analog films are done using digital processes.

Digital Distribution:

Once the cinema is processed and edited, it is ready to be distributed to the various movie halls. But now, instead of the individual heavy tapes being shipped across the world, the digital data is sent electronically over the Internet, leased lines, satellites and even inexpensive hard-disks and DVD’s. This saves time, money and effort. The data is encrypted while sending them across public networks like Internet.

Digital Cinema Servers:

The encrypted data is received and decrypted by the digital cinema servers which are located at the individual cinema halls. It then re-encrypts it and outputs the image data to the digital cinema projector and audio data to the sound processor. The theatre projectors of today support 128 bit AES encryption/decryption for media.

The digital cinema servers generally support the most common JPEG 2000 media playback format for compatibility as required by the DCI multi-vendor Compliance and may optionally support additional formats like MPEG-2 etc. The media block in the server which does the bulk of the work is reprogrammable to accommodate for future developments in image and sound formats. Generally, the industry standard audio/video formats are supported for the output.

The hard disks are generally in the form of an array and they support RAID to ensure redundancy of stored data. All the hard-disks, power supplies, cooling fans etc. are hot swappable. Some of them have a direct fiber termination option for connecting to the network.

The digital cinema projectors can be monitored and upgraded over the network. Some of them even provide a sort of an external remote to control basic functions like Play, Pause, Stop etc. There is an optional theatre management software to enable easy set-up, scheduling and management of multi-screen shows (usually in a multiplex with multiple screens) over the central network so that subsequent manual intervention may not be required.

Digital Cinema Projectors:

These projectors directly accept and play digital format images in high quality. Majority of the digital cinema projectors use DLP – Digital Light Processing technology to project images while some of them might use LCD or some kind of modified LCD crystals for projection. Some projectors come with media block as well which can store/decrypt the digital data.

Common projectors support 2k, 4k resolutions and have a brightness level in excess of 15,000 Lumens. They employ 1.5-7.5W Xenon Lamps (some times two lamps together) as a source of illumination (LED lamps are also getting popular) and the contrast ratio is around 2000:1 which is sufficient to show the minute variations of shades for colours.

The digital cinema projectors support input/output formats according to the DCI standards so that interoperability is not a issue. There are optional lenses to change the throw distances (as they are normally fixed for a particular distance) to adjust according to the theatre conditions. There are even 3D Lens adaptors which enable playing of 3D digital content, whose effect can be felt along with 3D polarizing glasses.

These projectors implement normal projector functions like keystone correction (to make the image appear like a perfect rectangle), electronic focus and zoom (with memory, so that the picture size doesn’t change on the screen when the display format is changed). Some projectors also help maintain the luminance levels automatically.

The digital cinema projectors must confirm to the SPB-2 and other anti-tampering requirements of the DCI – Digital Cinema Intitiatives which might want the projectors to require physical keys to open the body (instead of screws), automatically start recording logs when the projectors are opened and a host of other security measures.

Related Reading: Advantages and Disadvantages of Digital Cinema

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Digital Cinema is much more than using a digital projector to display the cinema… In this article we will have a look at the advantages/benefits of Digital cinema over the analog film based cinemas to understand why so many theatres/production houses in the world are converting to digital cinemas and we will also see some limitations of digital cinemas – why the film based cinematography is still popular in this near to digital world!

What is a Digital Cinema?

To understand the concept of digital cinemas, we need to understand about the film based cinematography – In a large number of cases (even today), the pictures are shot using analog film based cameras, then converted in to digital format for editing, mixing, re-recording and adding special effects and converted back to analog films for projecting them through the analog film based projectors.

Digital Cinemas use digital processes end to end – right from the capture (digital movies are shot using digital CCD based cameras with high resolution), storage (they are stored in digital tapes, hard disks or flash drives), processing (editing, mixing, re-recording, sound, special effects etc are handled in the digital format), display (digital cinema is displayed using digital projectors which are controlled by industry standard servers with management software in the theatres) and distribution (digital cinema copies are mostly transmitted electronically over the Internet or satellites or even hard disks).

Advantages of Digital Cinemas:

¤ The films used in analog cinemas (based on vinyl records) degrade with time, but digital images do not. And even if a DVD is scratched, it could easily be backed up in a hard disk or another DVD, for example.

¤ Digital cinemas can be shown and managed in the theatres by unskilled labour (with minimal training) as the management terminal is PC-based and simple to handle, unlike analog film based cinemas, which need dedicated personnel for receiving, prepping, showing, dismantling and returning the movie tape films.

¤ Distribution of digital cinema’s (electronically via Internet, satellites or even hard disks) are simpler, fast and in-expensive than the time taken and cost incurred for the shipping and handling of heavy film tapes.

¤ Supply rarely matches the demand in the movie industry – suddenly a picture might become a huge hit and the demand for showing it in additional screens might arise. It is much easier and faster to distribute additional copies for digital cinemas in those situations.

¤ Addition/deletion of scenes after the movies have been released is easier/cheaper with Digital cinemas.

¤ Piracy could be more effectively monitored with robust copy protection, encryption and water marking processes for digital cinemas. The chances of introducing a new anti-piracy technology is higher in the digital format.

¤ The solid state projectors used with Digital Cinemas are smaller and occupy less space than their analog counterpart.

¤ The digital tapes/external hard disks used in digital cameras (camcorders) cost much lesser than analog film based cameras – the same scenes can be shot many more times till the director is satisfied without worrying about the cost of the film tapes.

¤ The scenes can be previewed immediately after they are shot with a digital camera – so the director can immediately judge if a change in lighting conditions are required or a re-shoot is required etc.

¤ A lot of tools are available for introducing special effects in digital cinema. In fact, the scenes could be created fully using special effects/animation in the computers.

¤ There are management software’s available for digital cinemas which can automatically schedule the movies showing in various screens in a multiplex without manual intervention.

¤ There is a body formed by the major production studios called DCI – Digital Cinema Initiatives which is engaged in standardising the major specifications for digital cinemas to ensure interoperability between major vendors of digital cinema.

¤ Digital cameras are often highly configurable and use detachable modular components for flexibility and upgrade-ability. They can also record high resolution images up to 4096 x 2304 pixels.

¤ If a theatre can play digital cinemas, it can also broadcast events – live or hold meetings/conferences with minor changes in the theatre facilities.

¤ Digital 3D uses polarization instead of coloured glasses (used by older 3D cinemas) to portray the 3D effect. This ensures that the colour of the finished image is not corrupted.

¤ Digital cameras are considered to be better for indoor shooting/ shooting at nights with a very low light.

¤ Digital cinema is advantageous for low budget cinemas made with limited man-power as such movies  have lower budgets and alternatives are available for cheaper capturing, editing, processing, recording and distribution of digital cinemas.

Limitations of Digital Cinema:

¤ Even though the digital data may not get scratched/grained etc, the digital projector pixels would break/degrade over time.

¤ The quality of digital projection is comparable with analog film based projection. Some people feel that the quality of analog film based projection is better than digital projection and the image reproduction is more natural. But digital technology is improving everyday.

¤ Most of the theatres are equipped with film based projectors and to replace them entirely with digital projectors would involve a lot of cost and re-designing for the theatre owners.

¤ Digital data always has a higher risk of getting pirated than their analog counterparts.

¤ Digital technologies are prone to technological obsolescence. With newer technologies/improvements introduced so fast, the existing digital equipments might get outdated faster and some of them may not be upgradeable to newer technologies, introducing a higher risk on investing in them.

¤ Analog/film based cameras are even today considered better for outdoor/day-light shoots as digital cameras produce inconsistent images when exposed to high brightness environments.

¤ If the digital camera uses 4k resolution to capture digital images for good clarity, the cine projector displaying that image also needs to support 4k resolution to display the images at that clarity. But, there are a very few 4k projectors installed in theatres around the world.

¤ The digital standards of recording/playback keep changing and hence many digital cinemas are converted to analog films for storage and archival.

¤ Some Analog high-quality formats like IMAX etc, cannot be achieved by their digital equivalent cameras/ projectors.

¤ The chemical process of exposing film to light is well documented and understood by cinematographers. It also produces reliable images, based on film-stock. In contrast, each digital camera has a unique response to light and digital treatment processes are not mastered fully by cinematographers.

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This article analyses the advantages and disadvantages of using PC as a media player and proprietary media players (hardware based) for controlling the display devices (like Plasma/LCD) in a Digital Signage solution.

There are four main components of a Digital Signage solution – The Content server (where the content is created, organized and distributed centrally), the media players which receive the content at the local site and provide playback features (they can also control what is being played at individual display units), the display units like LCD screens or Plasma terminals which accept an input from the media players and display the same and the network which carries the content and helps in the communications between the various elements of a Digital Signage solution. You could refer to this article if you want a detailed analysis of each of the components of Digital Signage Solution.

In this article, we look at only the media player component (Please note that the media player can be totally discarded in case of small digital signage networks or if same content needs to be broadcast to multiple screens at all times in a medium sized network). But in larger networks, it becomes inevitable. There are two choices for the customers as far as the media players are concerned: They can use a standard PC as a media player (along with the media player software provided by the company) or they can use a hardware based media player appliance made specifically for playback. There are advantages and disadvantages of both, and we will look at some of them below:

¤ A PC is a computer and it is more of a general purpose device that can handle multiple operations other than the playback required for digital signage (For example, it can include administration and network management capabilities and even other tasks) but a dedicated media player appliance includes only the necessary features like playback of MPEG, MP3, VGA, DVI, Live TV, Streaming Video, transitions, scrolling ticker, multiple area layout, real time info. Basically, it has limited media support.

¤ Dedicated appliance based media players is more cost effective than having PC’s near each display device. Especially considering the operating system licensing costs etc, the price reduction could be considerable for a big project. But the cost depends on the vendor too.

¤ Appliance based media players are smaller and easily mountable near a display device. They don’t take up all the space of a CPU, for example.

¤ Appliance based media players are simple to install, configure and maintain. They also have a lower power requirement, when compared to PC’s. The maintenance costs and efforts in a PC are generally higher.

¤ An appliance based media player has limited screen segmentation and sizing options. They also have limited content aggregation from external sources. But PC’s can handle multi-zone, high resolution, dynamic content. They can even aggregate data from Internet sources like RSS etc.

¤ The storage capacity in an appliance based media player is limited, but in a PC, it is quite high and can be extended if required. This would be useful in situations where the connectivity to the central server is lost and content needs to be played back from the local storage.

¤ Both are proprietary – the appliance based media players and the media player software in the PC. But the PC hardware is generic. So, if ever the digital signage vendor needs to be changed, all the appliance based media players are not going to be of much use – as they are proprietary and work with only one vendor, at least right now. There is also no control on the prices for upgrades, additional add-ons, maintenance etc, as the reliance is on one vendor.

¤ PC’s can be hacked. But the appliance based media players generally don’t come with any external interfaces and hence it is harder to hack or take control over them.

¤ With appliance based media players, there is limited scope for adding interactive features. But with PC’s, the expansion and the addition of features and functionalities (like touchscreens which might need a local interface) is going to be easier.

¤ One PC can stream the content to multiple display units if all of them are nearby and would play the same content.

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In this article, we take a look at what is a digital signage, some applications of digital signage, components of digital signage solution like content server, media player, display devices and network.

You go to a restaurant. You order for your favourite food but it would take some time for it to be prepared and served. So, you casually look around. There is a huge display in the wall which is placed slightly above your normal viewing angle that catches your attention. The screen is divided in to three parts. There is a stock market ticker and latest news feed in the bottom which keeps moving from left to right (in a text box), there is also a weather forecast/ local/interesting info in the right hand half of the screen. And on the left half, there are advertisements on cell phones which keep rotating. You were thinking about buying a lesser priced cell phone, but one of the higher priced advertised model looks very interesting to you. You decide to check out both, when you go to the shop. Then the food arrives.

You were watching the display from a centrally controlled digital signage solution, which was installed in the hotel to keep the customers engaged during the waiting time as well as to provide some Out Of Home advertising. These Plasma/LCD terminals are normally owned and centrally controlled by some ad-agencies and hotels may also earn some additional revenue by putting them up in their locations, depending on a lot of factors like location of the hotel, category of people visiting them, the number of people visiting them etc. There are other applications to the Digital Signage solution like corporate communications, emergency messages, Out Of Home advertising, In-Store advertising, Public Information, Movie theatre advertising etc.

What is a Digital Signage solution?

A digital signage solution is a mass but targeted media channel which enables companies and organizations alike to communicate and promote their brands/products at places where they expect their target audience to congregate. The basic components of a digital signage solutions are: Content server (where the content is created, organized and distributed), Media Player/PC (from where the content is played to the screen), Display device(s)(from where people can view the content) and a communications network (through which the content is transported – like Internet). Digital signage can take any of the following form :

¤ Single Screen/ Single Zone display
¤ Single Screen/ Multi Zones display
¤ Multiple Screens/ Multiple Zones display with same content on all the screens
¤ Multiple Screens/ Multiple Zones display with different content in different screens

Here, ‘screen’ refers to the display unit like Plasma/LCD terminals etc, and ‘zone’ refers to an area of the screen (Single zone refers to full screen and multiple zones refer to multiple streams of content on the same screen each in its own allocated sub-region of the screen).

Individual components of a Digital Signage solution:

Content Server:

New content is always organized, created and distributed from here while the actual content is stored and played on the Media player.

First, content need to be created. If there is a huge network of display devices across multiple locations, it is imperative to decide what needs to be shown in those display devices. The content can be in any form like text, flash images, graphics, animations, IPTV, video, sound, interactive etc.

Many Digital signage vendors offer specialized software to create content in the format that can be understood by the media player and displayed in the display devices. The designer module comes with many clip art images, stored images and video, background templates etc, to help create professional looking content. They also allow the users to create text boxes where text can be scrolled, they help in partitioning the screen and letting the users decide which size fits which application. In fact, many such software’s help provide content from external sources like RSS feeds, weather reports, stock market quotes and other content. A lot of features like auto scaling of content for different screen resolutions, auto rotation of content/ads, portrait/landscape display, full screen effects/transitions etc are supported by them. They even allow real-time editing and updating of the content without interruption to the running media.

A Content server is provided by the vendors in the form of software, which runs on servers. They are the centralized source from where the content is organized and distributed. They can even distribute multiple channels of data – each stream with different content to be played at a particular group of the displays (based on geography etc). It allows the users to schedule content based on time tables. So, the users can decide which stream of content is played where and when and whether it should be repeated after a point of time etc. It helps create play list like routines in the case of media like video, flash images etc.

The media servers can take control of the input/output devices independently at each point of playback and each point in the network. So, remote monitoring and administration of individual devices is possible from the content server. Some vendors support back-end database integration (Like MySQL etc), for better organization of content.

Media Player:

A media player is an optional appliance/ PC (software based) which is placed near a display device for 24×7 playback of the content/media received from the content server. One advantage of using a separate media player is in applications where separate content needs to be played at different display devices. If all the display devices are going to play the same content, then streaming of the content from a single content server over the network would be a cost effective option. But a media player gives flexibility and redundancy (during network connection failures) where the previously stored content can be played once again.

The media player can be deployed individually (with a single display device) to play the MPEG video content (the source could be a DVD/flash drive) or it could also have a more complex configuration where there are a network of media players across many locations and content can be pulled from the central content server and played across the display devices as determined by the media players, individually at each location (or a group of display devices) whenever required. Both audio and video are played from the media player.

Display devices:

There are a lot of display devices that can be used for a digital signage solution. Some of the common displays that are used are: LCD Display, Plasma Display terminals, LED Video Walls, LCD/DLP Projectors, DLP monitors, etc. There are many more display devices that can be used in the future like Organic LED (OLED), e-ink (epaper type of display which is used in e-books like Kindle etc). In fact, some display devices have options for built-in PC/Chipset modules which can store and process the content server software, eliminating the PC/Media Servers and also the Content Servers. It can be used in individual applications.

Display devices used in digital signage solutions are increasingly building interactivity with the users by using innovative technologies like touch screen technology, blue tooth, SMS interactivity through cell phones and also social media interactivity (by publishing content from facebook, twitter etc).

Network:

Well, mostly it’s an IP Network (broadband, leased lines, 3G etc) that carry the content from the content servers to the media players and then to the display devices in real time. The last end might have some VGA cables or Audio/Video cables from the PC/Media players. Some times, even wireless networks are used in the last end to transmit data from the PC to the display devices using wireless adapters. Video over Cat 5 cables is the most cost effective technology to transmit content and there are even specialized ‘VGA video extender remote receiver over Cat 5′ devices to receive the content in IP format and convert it to VGA format, which is used to display images in the display devices. This could be more useful when the content is directly streamed from the content server to multiple display units in a broadcast modes with out using the media players.

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This article is more on the lines of why a control system is required for Audio/Video systems in a board room/ conference/meeting rooms and what all you can do with such a control system. We would also discuss certain advanced features supported by such A/V control systems.

The Audio/Video components in a Board Room/Conference room:

First, let us try to list down the various audio-video components that are normally found in Conference rooms:

¤ LCD/DLP Projectors (For projecting the content of a laptop/DVD player etc. on a bigger screen).
¤ Motorized Projector Screen (To provide a plain surface/screen for projected image. Some of them can be controlled by a remote control to automatically come down from a folded state, and go back).
¤ Motorized Ceiling Mount (In some conference rooms, the projector is hidden beyond the ceiling. To, bring it down automatically, a motorized ceiling mount is used along with a remote control).
¤ Audio System (This can be just amplifiers and speakers or additional devices like audio switchers and mixers are also used in a conference room).
¤ Microphones (Different type of microphones like podium mic, collar mic, table mic etc. are used for the speech to be audible in bigger conference rooms).
¤ Video Conferencing Systems (With Camera, codec and mic to see and talk to people from a remote location over IP/ISDN lines)
¤ Plasma Display/ LCD Monitors (This is used as a display unit for video conference systems or shows the output of a DVD player etc.).
¤ Document Camera (This is used to present some object or a page of text in real time by connecting to the projector or video conference system).
¤ PC, Laptop, Monitors etc.

What does an Audio/Video Control System do?

An Audio/Video control system primarily consists of a Central Controller where all the various audio/video devices converge and are controlled through some type of a control interface like a touch panel etc.

Imagine that you have an important meeting on a Monday. You walk in to the conference room in the morning, switch on the touch panel and select the meeting mode (one touch). The projector screen gets lowered automatically, the projector comes down from the ceiling with the motorized ceiling mount kit, the projector is switched on, your laptop source is automatically detected and the laptop screen is projected via the projector. Wait, it’s not yet over! The audio system is switched on (speakers, mixers, amplifiers etc) and the Mic’s are activated. The video conferencing system is switched on and the camera’s are focused as per their preset positions, ready for the conference to start!

With the same touch of a button, some vendors provide additional functionalities too: The lights are automatically dimmed (zone wise), the air conditioning system can be set to a specified temperature required for the meeting, the widow drapes can be automatically closed to ensure that it is dark enough to see the projector display properly.

The above is just for one preset mode, and there could be multiple such preset modes – For example, for a casual meeting, it could be programmed to just switch On the plasma display, DVD player, open the window drapes and switch On the Air Conditioning with a single touch of a button.

Some Interesting features of Audio/Video Control Systems:

¤ The touch panel can have a wireless (Wi-Fi) interface to connect to the Controller. This ensures that there is no cluttering of the cables and it is mobile. The speaker can annotate, draw and type directly over any computer source right on the touch panel and save them for future use. Trainers are also allowed to preview multi-video/source content on the touch panel prior to showing it on the display devices. There are button based non-touch type panels, flip tops, table top panels etc.

¤ The controllers can control all the audio/video devices through the LAN over the IP Network. That enables a centralized control over a large number of devices easier – the devices can be across the building or even across the LAN. Some vendors also provide web based control/management.

¤ Audio/Video devices, PC’s, Printers, lamps etc. can be programmed to automatically shut down when they are not used or at a certain point of time. The LCD projectors can be programmed to be switched off automatically when no active source is detected for a certain period of time. Or the whole thing can be coordinated to be switched on or switched off at certain times (like prior to a meeting, after a meeting) or on certain days (Switched off automatically during weekends etc).

¤ On a slightly advanced level, even motion sensors can be integrated to detect the movement of people in a particular room and when detected, a certain section of the audio/video devices can be automatically turned on.

¤ The lighting of the conference rooms can also be controlled. There are lighting dimmers which reduce the brightness of a certain zone of lights (near the screen etc.) when the projector is switched on. The lights can be made to glow in their full brightness during the discussion. The A/v controller and touch panel enable the centralized control of such lighting systems as well.

¤ In a HVAC centralized cooling environment, zones could be defined and certain sensors can detect if people are there in a particular zone and the Air Conditioning can be turned on only for that zone. This helps save energy.

¤ Audio/Video Controllers can help apply input compensation to help maintain consistent volume levels when switching between multiple sources. With some vendors, amplifiers are built-in.

The above points describe just some of the features to give a glimpse of the functionalities of the audio video control system in enterprise boardrooms/conference rooms. There are some disadvantages of such A/v controllers too as they are expensive and complex to deploy and program in large installations. Some of the cables used with such control systems are proprietary, and may not be available in the general market. The code is also proprietary but some of them give an API or SDK to extend the functionalities of the control systems.

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There are a few options available for viewing multimedia in bigger displays – LCD/DLP Projectors, Rear projection Video Wall Cubes, LCD Monitors and Plasma Display Terminals. Though the production of LCD Monitors have overtaken the Plasma display terminals, if you strictly consider the number of devices sold for both,  these two technologies are totally different from each other and the segment they address is also different. While 42″ and higher LCD monitors are available today, they are not as good as Plasma display terminals at higher sizes. LCD monitors do have a cost advantage as they are manufactured in bulk. And at smaller sizes, they are dominating the market today. The main problem with LCD/DLP display projectors is the lack of support for HDTV format and the overly costly Lamp (which needs to be changed every 2000 hours). But they give decent quality big display in any size you want (Up to 300″ Diagonal but at higher sizes, the images are of lesser quality). And yes, rear projection video walls too can give really big and high-quality images by arranging them together, but the cost of such video wall cubes can be justified for special purpose applications like control rooms or network monitoring stations of large ISP’s etc.     

Plasma display terminals:

That leaves us with Plasma display terminals. You should really see one to appreciate the quality of images they give. They start from around 32″ (Diagonal Screen size) and go up to 150″. But at 29″/32″, the CRT or LCD display monitors might be a better buy.  When you want to 42″ or higher display, Plasma display terminals are a serious consideration. They also come in sizes like 50″, 65″, 103″ etc.

Plasma display terminals have a very high contrast ratio (Don’t go with the manufacturers specifications though – each of them measure Contrast ratio in a different way). There is an ANSI standard, which none of them follow! Technically, they should have a higher brightness, but LCD monitors beat them on a well lit room. But there can be nothing better than a Plasma in darker conditions – their colour reproduction is more life-like with deep richer blacks. And they support a wide colour palette as required by the HDTV standard – but such minute differences, the human mind can never perceive! But when compared to LCD monitors, the colour reproduction is better. What colours you see in your laptop (Which is also LCD display), is not accurate – compare it with the colours of a CRT monitor and you will know why!

Plasma display terminals also support HDTV formats and the 16:9 wide-screen format required for HDTV. Some of them come with anti-reflective screens to reduce in-room reflections, and this could be a boon in moderately lit conditions.

Before some years, the maximum life of Plasma display units were advertised as 10,000 hours, but now they are being advertised as 60,000 hours. This is the time that takes for the Plasma display terminals to come to half of its brightness levels. So, the brightness does reduce as it is used more and more, but if the life is anywhere close to the advertised 60,000 hours, then it should be sufficient for most of the applications. And yes, there is no gas recharge required as long as you own the Plasma display.

Another striking advantage of Plasma terminal is their wide viewing angle. So, you can view it from any angle and the image quality or colours will not suffer. Compare this with LCD displays which have quite a narrow field of vision. Try going sideways and looking at your laptop, to understand this point. But the recent LCD monitors have improved on this. The Plasma display can be mounted both vertically and horizontally – could be useful for certain advertising applications/ displays in malls etc. Plasma display terminals have a faster response times for image display. Especially the super fast images of sports etc.

Plasma display terminals are slim and lighter than the CRT display units, and can be wall mounted too but LCD displays beat them on both counts. Partly because of the lower sizes, and partly because there is a full screen size glass mounted on a plasma display to hold the gasses intact.

Applications:

As you might have guessed, home theatre is a segment that is being targeted for Plasma. Except for the cost, there are no other major dis-advantages in this segment. Digital Signage solutions require Plasma display terminals. Advertising in malls, movie theatres, shopping complexes, hotels etc. could do better with a Plasma display. In the enterprise application, they are mostly seen in the reception or the board rooms. Plasma display terminals are the preferred choice for video conferencing output, as the pictures are more life-size. But with bigger displays, the small errors in receiving the video packets(due to packet drops etc) that might be negligible in smaller monitors could appear noticeable in Plasma. They are also used for making presentations in a small meeting room.

Disadvantages:

As was mentioned earlier, Plasma display terminals are not very clear in brightly lit rooms. Most of the normal accessories like VGA input, DVI Input, HDTV inputs, S-Video/RGB inputs, Speakers etc. might be available only at extra cost – so careful with this one. Screen burn-in (Especially visible with smaller text like spread sheets etc.) might affect a few of them. LCD terminals are much better at displaying text and small characters. Strange though it may sound, they do not come at sizes less than 32″ diagonal! They are heavier than LCD terminals because of the full screen length glass, and if it breaks, it might be harder to replace/repair them. The brightness decreases with usage, so for very heavy usage applications, this may not be suitable. The main disadvantage is the cost of production and cost of buying them. And the fact that they are not manufactured in bulk – when compared with LCD terminals.

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This article gives a short introduction to the various features supported by business projectors, and what are their advantages/ dis-advantages, if any. We discuss features in three categories: vital features, features that add-value and speciality features for the business category projectors.

Vital features of business projectors:

¤ Auto-Input: When you switch on your projector after having connected the PC to it, the projector should be able to detect the input signal automatically and start projecting the screen from PC. Alternately, it should also be able to identify if a video source / High Definition (HD) source (component input) is plugged in and project them automatically.

¤ Auto-Keystone Correction: A keystone error is formed when you tilt the projector slightly upwards to project to the screen which is above the viewing angle of the projector. A trapezoidal projector screen image is formed instead of the rectangle projection image that is expected of it. Normally, you need to get to the remote and adjust the keystone error manually. Some projectors allow you to do that by a single touch of a button. But there might be a slight loss in the image quality when this feature is used.

¤ Resolution and Display: Business projectors are either SVGA (800 x 600) or XGA (1024 x 768). Laptops are inherently XGA. So, when projecting from a laptop to an SVGA projector, there would be a quality loss and some shadow formed behind characters. In such cases, if you want a smooth picture, don’t do anything with the projector. Adjust the laptop display to SVGA. XGA Projectors are highly recommended.
The inherent display for projectors is 4:3 (Length by width), but laptops use mostly 16:9 display ratio. There are some projectors which can display 16:9 display ratio output, and that is recommended for laptops.

¤ Lamp Life: The lamp in a business projector is a consumable. It is required to change it every 2000 to 3000 hours. It is quite expensive, so it is better if the lamp prices/lamp is ascertained beforehand. It is also important to note the lamp warranty which is mostly for 3 to 6 months while the projector itself has  warranty of 2-3 years.

¤ Cooling Fan (Auto Off mode): The main power for the projectors normally need to be switched off only after the lamp is cooled for a minute or two. This is quite critical for enhancing the lamp life. But most of the users just remove the plug immediately after the presentation. Some projectors allow such auto-off by making the Fan run on saved power for about a minute, not affecting the lamp life. Water cooling method, if available is better and also gives a quieter operation.

¤ Freeze/Shutter: When you are running the presentation by connecting your computer, suddenly you need to refer a price list. But you don’t want everyone to see it on the projector screen. You can freeze the projector output to whatever presentation you are making (temporarily), see the prices, and release the freeze after you come back to the presentation. There is a digital shutter which temporarily blocks the lamp output, and you could write down something on the board to carry the explanation further, delete it, and then release the digital shutter to see the projector output back.

¤ Weight: There are projectors starting from 1 Kg, which are very light weight and easy to carry. But the lamp life of such projectors would be lesser as they generate more heat in a compact environment. If it is going to be fixed projection in a board room, it is better to go with the projectors which are larger and have more cooling fans.

¤ Ceiling Mountable: When the projectors are kept on a ceiling mount, they are essentially inverted upside down. So, the image also needs to be inverted upside down in order to appear straight for the users sitting on the conference hall. Most of the projectors do this, and they also come with a ceiling mounting kit, to fix them on a ceiling. Remember that if the VGA cable is longer than 20-25 meters, there might be a reduction in the quality of images that is displayed in the screen from the PC.

Features that add-value:

¤ Auto Shutter: There are some projectors, which have an auto shutter around the lens so that when the projector is switched on, the shutter opens and when the projector is switched off, the shutter closes automatically. This helps the projector lens not gather dust, which might otherwise be left open.

¤ Screen size/ Throw Lenses: The projectors can generally project images from 30″ Diagonal to 300″ Diagonal. But they can project only certain lengths from certain distances. To get a huge image from a very short distance, a short throw lens is used (This needs to be purchased separately). Similarly, to get a smaller image, from a longer distance, a long throw lens is used.

¤ Optical/Digital Zoom: When the projector is kept at a certain distance from the screen, and the projected image is slightly short of full screen, the optical zoom can be used to make the image slightly bigger. A digital zoom functionality is used to make a particular portion of the projected image appear in full screen so that more details can be seen. But this decreases the clarity of the image.

¤ Auto Focus/ Manual Focus: If the distance from the screen of a projector is changed, then the focus needs to be adjusted manually for a clear image. Some projectors can do it automatically.

¤ Lamp brightness selection mode: Let us accept it. We never need 2000 Lumens of brightness in a small conference room. In such cases, the lamp brightness can be reduced to lamp saver mode to increase the lamp life.

¤ Built-In Audio: Very rarely, the built-in audio might come handy. Especially when the laptop speakers are not audible. Some projectors can give a decent sound output along with image output.

Speciality features:

¤  Security: Some projectors offer the Kensington lock or a attachment to chain the projector to keep it from being taken away for physical security of the projectors. Some projectors also prompt the user to enter the password during start-up and only after the password authentication, the computer screen is displayed on the projectors.

¤ Direct projection from USB Stick: Some projectors enable direct projection from USB Stick, instead of having to carry a laptop along with the projector just to show a PPT file. There are also such presenter devices available from third party companies to plug in a USB device and start projecting. The only dis-advantage in this case is, all the files need to be converted in to image format for projecting them through the presenter device or USB stick.

¤ Two VGA Ports: If the projectors support two VGA ports, one of them might be connected to the CPU and the other can be connected to the monitor. This is because, unlike laptops, the monitor cable of the PC directly connects to the projector from the CPU. So, unless one more cable goes back to the computer monitor from the projector, the images might just be visible on the projector screen but not on the PC monitor! Some vendors allow both the VGA ports to be configured manually as input ports, and connect two laptops to switch over between them, during the presentation.

¤ Full Function Remote: Most of the projector functionalities are controlled by a remote control. There are also special remotes which have a laser pointer built in to them and also have a wireless mouse. So, users can use such full function remote control to control some mouse functionalities of the PC like going to the next page in a PPT presentation, for example.

¤ Wireless Projection: Click this link for a detailed article on wireless projection.

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