Projector Information Pages What is LCD? LCD (Liquid Crystal Display) LCD projection technology is the current leader of the pack, having captured the majority of the market share of all projectors sold. Most LCD projectors have three panels. Each panel is a prism that allows blue, red, or green light through its pixels. These separate colors are then converged and projected. Electrical signals turn on pixels within a set based on the resolution of the unit. LCDs are known to produce greater color definition, offering more shades or variations of color than single-chip DLP™ projectors. DLP™ projectors can sometimes burn definition out of the highlights and shadows with their vibrant colors. Newer LCD projectors include special optics enhancers like micro-lens array that minimize pixelization known as the "screen door effect." New LCD projectors have contrast ratios as high as 800:1. By comparison, DLP™ projectors contrast ratios are as high as 3000:1. The portability and brightness of LCD projectors have made them a popular choice for traveling presenters. The lightest LCD projectors weigh-in at about 4 lbs. Lumen Guide How bright should your projector be for your room? Below is a fast and easy reference for you to use to help determine how bright a projector you need for your room. Controlled 4:3 Screen * lighting Screen 72" 100" 120" 150" Low Size/ (43" x 57") (60" x 80") (72" x 96") (87" x 116") ambient Lumens light 1000 Some 1200 ambient 1400 light 1600 Bright 1700 ambient light 2000 2200 2500 3000 3500 3700 Controlled lighting- If you plan to use your projector in a room where there are no windows, such as a basement, or if you use your projector primarily at night, any of today's projectors will provide a bright image. Low ambient light- Little to no light entering room. Some ambient light- Some additional light in room. Slightly dimmed, window blinds leaking some light. Bright ambient light- Windows open during daylight hours, lights that cannot be dimmed like in an open office settings. Bright enough for audience note taking. *For video signals, your actual lumen output may vary from manufacturers specified levels, due to the lower luminance output from video signals. Variations differ from projector to projector, so contact a Projector People representative to find out more. Video Projector resolutions By Susan Jakobic - Data Image Systems, Inc In this ever-changing world of computer projector technology, manufacturers have made LCD projectors "smaller, lighter, brighter" over the last five years. I used to make the comment years ago when I was lugging around 40 lb. projectors with 250 ANSI lumens that someday projectors would be small enough to fit in my purse. Well that day is basically here. The Epson PowerLite series projectors weigh between 5.8 and 18.3 pounds, produce super bright images and come in three computer video resolutions: VGA (640x480), SVGA (800x600) and XGA (1024x768). These projectors can also handle wide-screen video images. Projectors are typically very "user friendly" in their set-up and operation. For the most part, users don't even need to read the manual. But there is one issue that is still very confusing to many people. It's the issue of "resolution" ... and which "resolution" projector should you purchase. I get calls daily from teachers, media specialists and technology coordinators who don't fully understand this resolution thing. What is resolution? Well, the resolution is the number of pixels, or size of the display area on your computer monitor ... specifically, the number of pixels across (horizontal) and down (vertical). More pixels mean greater resolution; smaller letters and more information can be packed onto the same-sized screen. People with small monitors usually use VGA, 640x480 or SVGA, 800x600 resolution. People with larger monitors often switch to XGA, 1024x768 resolution so that they can fit more information on the screen. On a Windows computer, you can check to see your computer's display resolution by selecting Settings>Control Panel>Display from the Start Menu. Click on the Settings About halfway down, the Desktop Area section will indicate your computer's current display resolution. You can change these settings (how much depends on your video card's capabilities) by moving the lever to the right or left. Windows will resize your display. You may want to experiment by viewing these different resolutions. Don't worry; you can always set the display resolution back to its original setting. On a Macintosh computer, users can go to Control Panels>Monitors & Sound (or just Monitors if you're using System 9) and select the Monitor button if it is not already selected. On the lower left, under Resolution, you will see the various selectable resolutions with the current resolution and vertical refresh rate indicated by the highlight bar. You may notice when reading technical specification information for a given projector, it states SVGA projector(s) will also handle XGA "compression". That means that you can feed an SVGA projector a higher 1024x768 signal, but since the projector's window, or display area, is only 800x600, it "squishes", or compresses, that higher signal down to fit in it's 800x600 window. Well, "something" has to give, so in this situation, small text and fine lines are affected and may appear fuzzy or out of focus. If you're projecting larger fonts or pictures, like a Power Point slide show, you may not even notice the compression. The same thing happens when an SVGA image is expanded to fill an XGA screen. So how do these resolution and compression issues affect which projector will be the best projector solution for your needs? Unless you're running high-end CAD lab applications or just purchased a new laptop computer "with the bigger screen" which is typically running at XGA resolution, SVGA projectors are more than adequate for classroom or auditorium presentations. An added advantage of an SVGA image on a given size screen is that although you will have less desktop area to show everything you do show will be bigger, especially those small application level fonts. Speaking of these new "laptops with the large screen", I'm aware that many schools are getting new laptops to allow teachers and administrators the flexibility of giving presentations throughout their districts. However, there are a few issues when using them with lower resolution projectors. If you have a new XGA laptop and already have an SVGA projector, can you use them together? The answer is "Yes, but there are a few "trade-offs" involved. You either view projected images in compression or need to make a few changes in your system settings (not a problem): 1. COMPRESSION: Since your laptop is running at the higher resolution, the projector has to display your images in compressed mode to be able to fit the 1024x768 laptop's window of information into the projector's 800x600 window. Remember, small text may appear fuzzy or out of focus. 2. CHANGE YOUR RESOLUTION: You can go into Windows and set your display's setting down to 800x600, but here is the "trade-off" ... you'll lose the ability to view your laptop screen along with the projected image. To get your computer to truly make this change you need to turn off your laptop screen and send the image only to the projector to be able to get the laptop to display the true 800x600 image. (this is a Windows "thing", not the fault of the projector). The procedure to turn off your laptop screen differs between laptops. It usually requires depressing the Function key and another function key at the top of your laptop's keyboard that is marked "CRT/LCD" or has a picture of a monitor. You may need to refer to your laptop manual or in-house computer technician to determine the proper procedure for your particular laptop. Actually, not being able to see your laptop screen isn't all that bad. If you're taking advantage of the Epson projector's remote mouse capability, you'll be standing in front of your audience and directing your attention to them ... not your laptop screen ... and that makes you look even better as a presenter! Projector Resolution Resolution refers to the number of dots of light that appear on a screen or a projection to make up a projected image. Take care to note the "native" resolution of the projector you're interested in - while a projector may be able to work with several different notebook computer resolutions, there is one native resolution at which it works best. Choosing the right resolution for your projector is as easy as knowing the resolution of your notebook. Don't forget, though, that if you plan on upgrading your notebook after getting a new projector you're best off buying a projector with a fairly high resolution that will match newer laptops. Your presentation won't come to a screeching halt if your notebook and projector don't have the same resolution. Virtually all models can accept higher or lower resolution images than their native resolution, using interpolation to either expand or compress the pixels that compose the image. However, expect to lower your standards a bit for for such interpolated images, since this will usually degrade the quality of the image. The most common resolutions, from cheapest to most expensive, are VGA (480x640), SVGA (800x600), XGA (1024x768), and SXGA (1,280x1,024). Resolution of projectors is differentiated in four categories UXGA (1,600 x 1,200) - UXGA is for very high resolution workstation applications that are detail or information intensive. These are expensive projectors that support a broad range of computer equipment. SXGA (1,280 x 1,024) - SXGA products are high resolution, and notably more expensive than XGA. These products are targeted for high-end personal computer users and low-end workstation users. They are used primarily for command and control, engineering and CAD/CAM applications where acute resolution of small details is important. XGA (1,024 x 768) - XGA is suitable for relatively high-resolution images from videos, spreadsheets, and graphics. XGA projectors are generally more expensive, and are an equally popular resolution format to SVGA. They have gotten more popular as XGA resolution computers have become more plentiful. SVGA (800 x 600) - This is a very popular resolution today, because of their attractive prices and great images. SVGA is good for projecting simple graphics and presentations. Personal computers often have an SVGA or XGA resolution. Higher Resolution: High-resolution projectors are able to show more picture details than low-resolution projectors. Also, since there are more pixels used to make the image, each individual pixel is smaller, so the pixels themselves become less visible on the screen. Lower Resolution: Lower resolution projectors are much less expensive, and they can produce images that are just as bright and attractive as higher resolution machines. Unless you really have a need to display fine details, lower resolution products will be your best bet from a cost perspective. You need at least this much Consider this If you mainly use: resolution: projector class: PowerPoint type presentation software, clip art, or simple 800 x 600 SVGA graphics (pie and bar charts) Excel type spread sheets and detailed graphics such as 1,024 x 768 XGA (architectural drawings) CAD/CAM applications or ultra high-resolution graphics 1,280 x 1, 024 SXGA Projector Buying Considerations Contrast - Contrast is the ratio between the brightest and darkest areas of the image. Contrast ratios should be high (400:1 or higher) to get the best video image or the most legible computer/graphics image. Room light substantially impacts contrast ratios. Consider projectors with very high contrast ratios if you intend to use your projector with the lights on. Rear Projection Capability - If you want to set up a rear-projection system, the model must have the ability to reverse the image so that it appears correctly on the screen. Most models have this feature today, but if you need it, you can eliminate any projector that does not have this capability from your short list. Video Format Compatibility - The standard video formats are NTSC, PAL, and SECAM. Many projectors accept all three. Video Signal Standards - Most video devices accept composite and S-video as two types of signal transmission. Almost all projectors will accept both inputs. However, there is a new standard known as component video. Some of the new DVD players offer a component video output signal in addition to composite and S-video. You will also be able to get component video signals from some satellite systems. Televisions and projectors that are equipped to handle the component video signal will produce a superior video image than those, which cannot. If you are interested in optimizing video performance and you have a video source that offers component video output, check to see which of the projectors on your list are capable of accepting a component video signal. The spec sheet may say component video, or alternatively (Y, R-Y, B-Y) or YPbPr. Ceiling Mountable - If you want to mount your projector on the ceiling, it will need the capability to project the image upside down. The large majority of projectors do this today but you must verify that a ceiling mount exists as an option for this product. Universal Power Supply - Universal power supply means the unit will automatically detect different voltage levels, such as 110 volts in the United States or 220 volts in Europe, and adapt easily to them both. If you plan to travel with your projector in countries with different power systems, this is a must. Multiple Computer Ports - If you want to connect multiple computers or video sources to the unit simultaneously, you will need multiple input jacks to accommodate this. Data Signal Ports - Most importantly, make sure the model you choose supports the computers you intend to use now and in the near future. This is a significant investment and the pace of change in the computer industry should be a consideration. PC and PC compatibles are nearly always supported with a direct connection, but Macintosh may be a separate connector or require an adaptor. If you are using a workstation, check that the models you intend to use are supported in the manner you intend to use them and if adaptors are needed, know whether they are included or an additional cost item. Uniformity - The uniformity of brightness and contrast between black and white are just as important to overall image quality as the oft-cited brightness figure. Manufacturers who focus too intently on boosting the lumens number may offer models that produce noticeable hot spots in the center of the picture or washed-out images due to over-lighting. Uniformity and contrast figures can help you pinpoint these potential problems. Color temperature - This is often referred to as "white point" and it affects how accurately a projector displays whites and grays. Historically, color temperatures of 6,500 and 9,000 degrees Kelvin have been considered "ideal" temperatures for "true white" in video and data modes, respectively, and they are still good reference points. Our brain's perception of white varies as the light source changes, and today's brighter light bulbs generally give us different shades than their predecessors did 60 years ago, when these lighting standards were created. Specific viewing environments also affect our perceptions of white and other colors. Color reproduction and sharpness - These also affect the image quality, but they are harder to quantify without very technical data. AV Avenue's image comparisons (found in various product reviews) can be helpful in evaluating these criteria, and they will help you understand what to look for in a selection of projectors. Standard LCD - These LCD (liquid crystal display) projectors have one panel of LCD glass that controls the three primary colors. These projectors are becoming less common in the projector marketplace, as polysilicon LCD and DLP projectors gain popularity. Polysilicon LCD - These projectors control colors through three panels and are considered to be of higher quality than standard LCD. The projection through three panels allows polysilicon LCD projectors to have higher color saturation than a standard LCD projector. DLP - DLP (digital light processing) projectors use a single chip with thousands of micro mirrors to modulate the lamp's light and project it through the lens. DLP systems are composed of over 400,000 tiny mirrors, which modulate light from a lamp and project the "modulated" signal out through the lens onto a screen. This technology is also referred to as DMD (Digital Mirror Device). DLP projectors are one of the more common types of projectors on the market. Glossary of Common Presentation Terms A Ambient Light: Any light in the viewing room created by a source other than the projector or screen. Aspect Ratio: The ratio of height to width of a frame or screen. In a 4:3 aspect ratio, the width of the image is 4/3 times the height. Most current TV and computer video formats are in a 4:3 aspect ratio. A 15 inch monitor is 12 inches wide by 9 inches high (9*4/3 = 12). A resolution of 640x480 is a 4:3 format (480*4/3 = 640). SXGA is a 5:4 aspect ratio is (1280x1024), HDTV is 16:9 for that movie theater feel, and 35mm slides are 3:2. ANSI Lumens: ANSI stands for American National Standards Institute. It is a standard for measuring light output. Different lamps play a role on light output. Halogen lamps appear dimmer than another metal-halide, even if the two units have the same ANSI lumen rating. Type of LCD technology (active matrix TFT, Poly-Si, passive), type of overall technology (LCD vs. DLP vs. CRT), contrast ratios, among other factors can also affect the end result. Aliasing: Jagged edges along the outer edge of objects or text. Anti-aliasing refers to software adjustments that correct this effect. This effect is created by inadequate sampling techniques in computer-produced images. B [ top ] Backlit: A remote control, projector control panel, or other object illuminated from behind. This can be helpful when working in darkened rooms. Bandwidth: The frequency range of a particular transmission method. In video systems, this value is expressed in MHz, and the better the signal, the greater the bandwidth required. Bit Mapped Graphics: The type of graphic that is defined and addressed on a bit-by-bit basis which makes all points on the screen display directly accessible. BNC: Used with coaxial cables, this connector receives all R, G, B, H-Sync and V-Sync information, and composite video. Build Slide: "Build series" slides show audiences where a topic is heading a line at a time. Each new line added appears in a bright color while previous the line drops back to a darker color. Button: A graphic element inside an interface that represents an embedded action or function. C [ top ] Color Temperature: A method of measuring the "whiteness" of a light source. Metal halide lamps produce higher temperatures than halogen or incandescent lights. Clip-Art: Graphics that have been previously published which can be imported into a presentation simply by copying and pasting. Color Resolution: The total number of colors available, expressed in bits per pixel. Compatible: When different hardware or software can be used together without a major over-haul. Contrast Ratio: The ratio between white and black. The larger the contrast ratio the greater the ability of a projector to show subtle color details and tolerate extraneous room light. There are two methods used by the projection industry: 1) Full On/Off contrast 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. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. 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. When comparing the contrast ratio of projectors make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector. D [ top ] Diagonal Screen: One corner of a screen to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. If the screen is 12x12, it would still rate 15FT diagonal since that would be the diagonal usable. Desktop Videoconferencing: Videoconferencing via personal computer. Digital Light Processing (DLP): Developed by Texas Instruments, DLP is a light processing system that utilized hundreds of thousands of tiny spinning mirrors to reflect images. Many feel it is the most accurate reproduction of color and images available today. Dot Pitch: The distance between the dots on a CRT display. The closer together the dots are create a higher resolution of a displayed image. Dithering: Making digital images appear smoother by adding color or random noise during the digitization process. E [ top ] EGA: AKA Enhanced Graphics Array, EGA is an image which displays 640 pixels by 350 lines with 16 colors from a palette of 64 colors. F [ top ] Front Room Projector or Position: A unit that sits close to the screen, its short throw lens projects an image size that is about the same as the distance to the screen. 6FT diag. screen = 6FT distance. Generally the unit might be as close as 3/4 the screen size or as far as 1.2 times image size. Front Room Projector or Position: A projection unit that sits close to the screen, thereby requiring a shorter throw-distance. Flat Screen: A CRT made more flat than a standard tube by using more than one electron gun. Beneficial to people who require concise reproduction and great detail such as graphic designers. Focal Length: Focal length is the distance between the lens and its focal point. A smaller focal length indicates a wider-angle lens. G [ top ] Genlock: Synchronizing signals between two video sources, which is necessary when overlaying computer graphics on an image from VCR, camera, or videodisc player. Ghosting: A shadow or weak secondary image as seen on a monitor or display which is created by multiple path broadcast transmission errors. H [ top ] High Gain Screen: A screen that uses one of more methods to collect light and reflect it back to the viewing audience, which will increase the brightness of the image over a white-wall or semi-matte screen. H Sync: AKA Horizontal synchronization. A marker, which indicates to a computer or video signal that it, is the beginning of a line. HDTV: AKA High Definition Television. High definition, wide-screen television broadcasting with digital audio. Horizontal Frequency: AKA kHz, the total number of horizontal lines scanned per second in a displayed image. Horizontal Resolution: The total number of vertical lines individually perceived across the horizontal rows of a monitor. Hz: AKA Hertz. A measure of frequency in cycles per second. Used to express the frequency of an electrical signal or event. I [ top ] Invert Image: Many projectors that are ceiling mounted are mounted upside down. Invert image corrects the image digitally so your projected image is not also upside down. Interlacing: Technique used to reduce flicker caused when the first created video field fades while the next is being written. J [ top ] JPEG: AKA Joint Photographic Experts Group. An international group, which is working, on a proposed universal standard for the digital compression and decompression of still images used in computer systems. The JPEG idea reduces image size as much as 65:1 and still maintains image integrity by getting rid of subtle color differences the human eye can not see. K [ top ] Keystone Correction: A projectors ability to correct the effects of "pointing up" or "pointing down" at a screen enabling the projector user’s audience to view a rectangular image rather than one with a wider top or bottom. Keystoning: The distortion (usually a wide-top narrow-bottom effect) of a projected image caused by a projector "pointing up" or "pointing down" at its screen. Named after its similarity in shape to the keystone used in constructing an arch. L [ top ] LCD AKA liquid crystal display. This technology comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. They are used in many notebook computer displays and also used as technology inside a projector to project high-resolution digital images. Laser Pointer: A hand held device that emits a thin laser beam that focuses a bright dot (usually red) on projected images or just about anywhere. Used by presenters to direct the viewer's eye to a particular point of interest. Lenticular: A screen surface that has an embossed geometric shaped pattern that affects view/angle performance and reflection of ambient light. Long Throw Lens: A lens designed for projection from the back of a room. Long throw lenses would be used a projection booth in the back of a theater, or from the back of a large classroom. A long throw lens would have to be 50 to 100 FT back to project a 10FT diagonal image. M [ top ] Metal Halide Lamp: The type of lamp used in most high-end portable projectors. These lamps output a very "hot" temperature light, similar to lamps used in streetlights. Metal Halide whites are super white (with a hint of blue) and make Halogen lamp white very yellowish by comparison. Multimedia Presentations: The integration of text, art, graphics, photography, animation, audio, and video into presentations. Multiplexing: The condensing of many signals into a few or one signal that still represents all of them. An LCD panel performs the de-multiplex function. It takes video signals that contain whole frames of video data and displays them as individual signals on each pixel. N [ top ] NTSC: The USA’s broadcast standard for video and broadcasting. It is actually a lower resolution than systems used in most of the world. However, by the year 2002 stations will be required to broadcast higher resolution video signals. Network: Allows two or more computers to exchange information quickly and easily. O [ top ] Output: Material that a computer generates from its memory for display on a monitor or for transfer to other media, such as paper or magnetic storage such as zip or floppy disks or a CD-ROM. Overlay: The capability to superimpose computer-generated graphics and/or text on motion or still video. Overhead Projector (OHP): An OHP is designed to project images from transparencies onto a screen. P [ top ] PAL: AKA Phase Alternation by Line. The standard color system used throughout Western Europe, except in France. Poly-Si (silicon) LCD: A popular LCD technology for the top of the line LCD projectors, which results in increased color saturation, with contrast ratios above 200:1. Pixel: Short for picture element. The smallest element in a displayed image. A color pixel is a combination of red, green and blue subpixels. Total pixels are usually expressed in horizontal x vertical dimensions (e.g. 640 x 480). Power Zoom: A zoom lens with the zoom in and out controlled by a motor, usually adjusted from the control panel or a remote control. This is as compared to Digital zoom, which does this same function Digitally. Presentation Ergonomics: The study and science of optimizing relationships between a presenter and the presentation environment. Projection Axis: Direction of the "imaginary" line that extends from the center of the projection lens through the center of the screen. R [ top ] RGB: Red, Green, Blue; the type of monitor generally used with computers. RGB input or output often referred to as Computer input or output. RCA connector: The connector used with VCRs and stereos for composite video signals and audio. Real Time: The transfer of data that returns results so quickly that the process appears to be instantaneous. Rear Projection: Projecting an image through a translucent screen material for viewing from the opposite side. This method of projection is also an option for home theater use in large spaces. Remote Mouse and Keyboard Control: Allows presenter complete control of computer presentation without direct access to projector. Allows for freedom of movement. Resolution: Number of pixels (or dots) per unit of area, measure in number of pixels wide by the number of pixels high that can be displayed on the screen or monitor. More pixels per unit of area produce a higher resolution. RS-232C: A cable that connects a computer and its peripherals. S [ top ] SaBRE: AKA Subtractive Bi-Refringent Effect, a technology that allows two panels rather than three to generate the full 16 color VGA palette. The top panel provides white, magenta, blue, and cyan; the second brings colors from white through yellow and to red. SECAM: The French broadcast standard (used in some other international markets) for video and broadcasting. Like PAL, SECAM is also a higher resolution than that of the US, until 2002. Simulated color: Also known as "false color," or "colorized." Projected colors that are not the same as the original image. Some products use a single, colorized LCD, often with purple for dark shades and yellow for light shades (purple background/yellow foreground). Therefore, what should appear on a screen as blue may be yellow, green may be purple. SVGA: AKA Super VGA. Refers to a computer signal that is higher than the standard VGA resolution of 640 pixels by 480 lines with 16 or 256 colors. SVGA graphics cards may output resolutions such as 1024 x 768, 1280 x 1024, 1600 x 1200 pixels or higher, with 16.7 million colors displayed. T [ top ] TFT: AKA Thin Film Transistor. A technology used to make Active Matrix LCD panels wherein each pixel has its own transistor switch. Throw Distance: Length of the projection beam required for a projector to produce and image of a desired size. TSTN: AKA Triple Super Twist Neumatic. A technology used to make Active Matrix LCD panels wherein each pixel has its own transistor switch. U [ top ] UXGA: Resolution of a computer generated image. A UXGA projector will be able to display a 1600x1200 image from a computer running in a UXGA video mode. If the computer is not running in a UXGA video mode, typically the projector will resize the image to 1600 x 1200. V [ top ] VGA Resolution: VGA Resolution normally refers to a 640 x 480 pixel display, regardless of the number of colors available. Originally VGA was 640 x 480 16 colors. V-Sync: AKA Vertical synchronization. A marker in a video signal for the beginning of a frame. Varifocal Lens: A projector lens that has three focal elements contained in a single assembly. Vertical Resolution: The total number of horizontal lines that can be perceived in the vertical direction of the screen. VGA: AKA Video Graphics Array. This is the standard interface for the IBM PS/2. It is the only analog graphics card IBM has used (other cards handle digital information) 720 x 400 in the text mode, graphics mode 640 x 480 resolution. Video Compatibility: Ability of computers and projection units to transmit and receive data to read and/or project various video tape standards such as NTSC, PAL, SECAM and S-VHS. W [ top ] Whiteboard: Document-conferencing product that lets multiple users simultaneously view and make notes on a document with pens, highlighters and drawing tools. X [ top ] XGA: Acronym for Extended Graphics Adapter. A standard introduced by IBM that includes VGA as well as resolutions up to 1024 pixels by 768 interlaced lines. Y [ top ] Y/C Connector: A 4-pin DIN connector used for high-end S-video sources. Y-Cable: A cable that splits the monitor signal so that it will work simultaneously with both a monitor and a LCD panel.\ Z [ top ] Zoom Lens: A lens with a variable focal length. This translates to being able to adjust the size of the image on a screen by adjusting the zoom lens, instead of hAudio Visual Innovationsng to move the projector closer or further.