Keystone
If the projector is not placed perpendicular to the screen, the image is not rectangular – this is a keystone error. Most projectors offer digital keystone correction in the horizontal and vertical planes.
Lamp Life
Lamp replacements contribute a major part toward the total cost of ownership, you should consider lamp life and lamp costs at the time of purchase. On an average, a lamp can last 2000 to 4000 hours. This doesn’t mean that the lamp ceases to function exactly at that time, but it’s an estimate. It may last longer, but the output from the lamp does diminish over time
Letterboxing
Some movies are shot in widescreen (16:9 or wider) – but to display them in standard width video formats (4:3 or square), you will see black bars above and below the display area. This is called letterboxing.
Aspect Ratio
This is the ratio of the width to the height of an image or screen. It is expressed by two numbers separated by a colon. For instance, in a 16:9 image, if the length of the image from left to right is 16 inches, then the height will be 9 inches.
3LCD
A 3 colour LCD system uses individual LCDs for red, green and blue. The light from each LCD is combined using a prism to create a final image. It usually offers better quality than single chip LCD or DLP designs.
Screendoor Effect
This happens if you’re sitting too close to a projector – fine lines will be seen between the individual pixels on the screen/wall. A screendoor effect usually doesn’t matter if you’re displaying static images (or a presentation) but it affects movies/videos.
Artifacts
Flaws or defects in the image caused by a number of factors – poor/inadequate resolution, transmission losses, poor quality video cables or not using the correct cables.
Contrast Ratio – (ANSI vs Dynamic)
This is the difference between the darkest and the brightest pixel. Higher is always better – it points to the device’s capability to render darker areas better while keeping lighter areas well lit. Dynamic ratio is often higher (and unrealistic) – it measures the difference between an all-white image and an all-black image. ANSI contrast provides a platform – an even playing field with which to conduct comparisons. It is measured using a pattern of 16 alternating black/white squares.
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