The two things to remember when buying a portable multimedia projector are that it is going to follow you and your notebook computer everywhere, and you are going to use it in front of people, so it had better be light and reliable because your back and your credibility are at stake. Until 1995, the only types of projectors were conference ones, occasionally moved from room to room but rarely taken outside the office, and fixed projectors like those permanently installed in large halls or cinemas. The portable projector, also called personal or desktop projectors, appeared only recently. The definition is still vague, as their form and weight vary considerably between vendors, from the laptop design and sub-four kilogram weight of the InFocus LP425, to the bulky, 7.5 kg Philips ProScreen 4750. Vendors cannot even agree on a common name for this category, which projects what you see on a computer monitor on to a larger screen. Some call them multimedia projectors, others data/video projectors, depending on the type of applications they want to promote. What the industry unanimously agrees on is that this relatively new market segment is expected to be hot. 'The portable segment is really taking off and will dominate the market because these projectors are now small enough while providing the same image quality and same performance as the conference projectors,' Vincent Leung, marketing manager of InFocus Systems, said. InFocus, a US hi-tech company that first developed colour LCD panels, is an industry leader in data/video projection products and services with a 26 per cent global market share. Mr Leung said projector design was highly influenced by the PC industry. 'Like PCs, projectors are no longer considered as shared tools, and are becoming more and more personal. They are increasingly perceived as PC peripherals,' he said. 'Typical PC features such as universal serial bus [USB] connectivity, firewire high-speed connection and digital video will be available and incorporated into projectors soon.' Brightness would increase, and size would be reduced to the extent that projectors would be designed to suit hand-held devices. The emergence of VGA PCMCIA cards and of Pocket PowerPoint software for Windows CE hand-held computers were driving the industry in that direction, he said. This year, paper transparencies and 35 mm slides still dominate the US$10.5 billion global business presentation hardware market. But the electronic media segment - 22 per cent of the market - is growing mostly because of the push from projectors. Mr Leung said that despite the financial crisis projector sales were still healthy in selected markets. 'Given the current growth of unemployment, a lot of governments are putting emphasis on vocational training which is one of the main markets for presentation tools,' Mr Leung said. 'Also, because of the crisis, many countries like Hong Kong are turning themselves into service economies, which are based on communication and also require presentation tools.' Eduserve sales executive Dominic Yuen believed the local market for projectors would grow 30 per cent this year. The company is a leading seller of products for classroom teaching and conference communication. Most projector makers leveraged their experience in producing liquid crystal displays (LCDs) - a technology which consists of shining light through a transparent panel - and expanded it to projectors. The technology has been so crucial that many people continue to call them LCD projectors, which is misleading because LCD is no longer the dominant technology. Now, the most common technology is polysilicon active matrix, another cheap and mature technology providing better image quality than conventional LCDs. The true revolution, however, came with digital light processing (DLP). Early data and video projectors were bulky, not very bright, and required all external light sources like windows or overhead lights to be covered or turned off. DLP, pioneered by Texas Instruments, has greatly improved the light output and resolution, and shrunk the size of projectors. Detractors say that because it is chip-based, DLP is less reliable than the more mature LCD or polysilicon technologies. Nevertheless, projectors have shrunk and become sharper as a result. An example of this is the latest member of the InFocus ultra-portable LP400 series, the LP425, which weighs a mere 3.1 kg. InFocus' sales pitch is that 'the biggest thing people should bring into a meeting ought to be ideas'. The challenge is keeping the size small while increasing the number of ANSI Lumens, the industry standard for measuring brightness levels. Brightness is an important consideration when buying a projector. Bright images do not require room lights to be dimmed, which enables the presenter to maintain eye contact with his or her audience - and keep it awake. However, brightness is not everything: images that are too bright lose texture and depth, so potential buyers also have to check the image quality. Powerful light output also means heat. So, along with brightness and image quality, it is worth checking the noise level of the cooling fan. A noise level of more than 40 decibels might be distracting or irritating to the audience. In the minds of most users, brightness goes along with image quality, and no one should be ready to trade one for the other. Hence, vendors have developed different technologies to improve the image quality. These include NEC's AccuBlend, a proprietary pixel-bending technology that compresses resolutions and offers better images; Epson's Biscuit (Balanced Image Size Conversion UnIT), a technology that enables projectors to offer similar image resolution no matter what quality comes from the computer; and Philips' Limesco, which uses a full bit-mapping process to prevent distortion regardless of the signal source. Whatever the technology involved, it should be transparent to the user and should not impede use of the projector. A good projector is one that offers enough I/O (input-output) channels, connects easily to different components such as a video or a PC and offers as much compatibility as possible with other peripherals and display resolutions. Today, the most common resolution is still SVGA (800 x 600), but more projectors are compatible with the higher XGA resolution (1280 x 1024). Multi-voltage is another feature to look for to ensure your projector can use any power source without relying on a converter. Reliability is also an issue as there is no more embarrassing situation - for the audience as much as for the presenter - than when a projector breaks down. Usually a projector comes as a self-contained unit with few moving parts. If handled carefully, your projector can last forever.