Verzending
Projection Adviser
- Image Quality
- Resolution
- Brightness
- Contrast Ratio
- Colour Rendering
- LCD
- DLPTM
- Poly Silicon-Technology
- Presentation Features
- Compression and Resizing
- Keystone Correction
- Projection Ratio
Image quality
The image quality of a data-video projection is composed of- Resolution
- Brightness
- Contrast ratio
- Color Rendering
- Focus
Resolution
therewith you refer to the number of pixelss. Mostly, funded the indication of pixelss per line and column because this explains simultaneous the picture size. Known until now are:| VGA | 640 x 480 pixels | outdated, projectors no longer available; |
| SVGA | 800 x 600 pixels | sufficient for a simple presentation and office-usage, favorable for video, because the number of lines of video standard comes close; |
| XGA | 1024 x 768 pixels | for professional presentations, grafics and large tables; |
| SXGA | 1280 x 1024 pixels | for CAD and simulations; |
| UXGA | 1600 x 1200 pixels | Workstation-resolution |
| MAC | 832 x 624 or 1152 x 870 pixels |
for Apple MacIntosh processors |
| more Workstation-resolutions | ||
| NEXT | 1120 x 832 pixels | |
| SUN, SGI | 1152 x 900 or 1920 x 1200 pixels |
|
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Brightness
The brightness of the image on the screen depends on the image size and the efficiency of your projector. Which capacity - verbalized in luminous flux, that the projector can transmit - do you need?
In Datasheets you`ll mostly find the phrase ANSI-Lumen. That is only an expression for a certain measurements instruction from the american standardisation institute ANSI, comparable to the german DIN, which averages over 9 measuring fields.
What can I do with this value?
The luminous flux which emits from the objective distributes on the screen. The larger the screen, the darker the image. You divide the luminous flux over the screen and get a value that has following rules:< 100 Lumen/qm: kno picture presentation possible
between 100 and 250 Lumen/qm: shade good
between 250 and 400 Lumen/qm: slightly shade
> 400 Lumen/qm: projection in bright rooms. protection from direct sunlight is necessary
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Contrast Ratio
As important as the reachable brightness is the contrast ratio. That is the area between the brightest and the darkest point, in which grayscales are presentable. The values are technological limited. With a lower contrast ratio you can't display black, there is always a grey fog in the image. Modern projectors can reach a contrast ratio higher than 350:1 in which the area is barely usable as long as there is ambient light. To display black you need darkness. Therefore cinemas are gloomy! The latest projectors with DLP-mirror technology have a contrast ratio higher than 500:1 and are adequate for quality video presentations.go up
Color Rendering
The accuracy of colour value is important for the image quality, too. The best available technology is the display of 16,7 million color nuances, this is a color depth of 24 bit. All portable projectors have minor variations in the color display, conditional on technology. Therefor the display is not as accurate of color as a reference display. A comparable quantity is the color "temperature in Kelvin", a measure for the color of light. Daylight has a color temperature at 5600 Kelvin, while the metal halide lamps in projectors have temperatures higher than 6000 Kelvin. That makes the light bluish and flashy.There are also discrepancies because of the imaging device.
Cheap Polysilicon devices tend to jaded 'candy colors' and discrepancies in the illuminants. They are displayed in discrepancies from a neutral grey. Devices containing DLP-mirror technology display a neutral grey. There are some discrepancies in the red tones, that are caused by the filters from the wheel of color.
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LCD
Is the shortcut for liquid crystal display. This displays, which are based on liquid crystals, are applied in many technical devices like calculators, notebooks and also in projectors.go up
DLPâ„¢Â
Digital Light ProcessingDas Digital Light Processing Heart of this technology is the Digital Mirror Device (DMD), a matrix of digitally controlled tilting mirrors. One tilting mirror corresponds to one pixel. Depending on the mirror position light is projected through the objective or no picture element is created. The longer the mirror is in projection position, the brighter the picture element gets in the eye of the beholder. The space between the mirrors is extremely small, so there are only minor losses in the power of light. Very small projectors can be build up with the 1-chip-technology. The light gets divided into red, green and blue by the wheel of color. Than every color is send on the reflecting DMD-chip. The fast sequence of red, green and blue charts get together in the eye of the beholder. This images are more color balanced than on Poly Silicon Devices.
1-Chip DLP-Projektoren
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Poly Silicon-Technology
BIn Poly Silicon Devices 3 LCDs are used. Every Display has picture elements in the resolution of the projector. The projection light gets dividet into red, green and blue by a system of mirror filters. The LCD picture elements act like light valves and create a monochrom chart. Through the block of prism and the objective the image is projected on the screen.Poly Silicon is more suitable for projection than the former used amorphous Silicon Displays, because they are especially translucent and the displays are very small. For this reason small powerful projectors can be build up.
The illustration shows the imaging device ones Poly Silicon Projector
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Presentation Features
Tools that can make your presentation dynamic and impressive:Freeze: The projected image stands still during the presentation, thus you can go through your pc-presentation without showing it to the audience.
Digital-Zoom: enlarge display details
Blank, Mask: shades the image, thus the attention is on the lecturer, the projector is operable.
Mouse Control:The projector remote control takes over the mouse control. The lecturer only needs one device for projector and computer.
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Compression and Resizing
Nearly all projectors can display higher resolutions than picture elements are physical available. At this display mode rows and colunns are omissive and divided on the surrounding picture elements by an algebraic method. A similar method is used to extrapolate smaller resolutions to the complete picture - the resizing. The images always look a little blurred although the objective adjustment is correct.go up
Keystone Correction
During an upward projection the image is distorted (Keystone Effect), as shown in the illustration. To prevent this effect most projectors adjust the objective so that the image is projected without Keystone Effect while parallel projection above the desk level. If the projector is operating in ceiling installation, the image must be turned electric. If angular projection is neccesary the best method is to turn the screen. Therefor you need Keystone Brackets. The electric Keystone Correction should only be used in exceptional cases, because the image quality is affected. You get similar effects as at the compression.go up
