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// TECHNICAL THEORY
To really understand just what is now possible, it is necessary to have a basic understanding of how this can be achieved.
Although widescreen television has been around for the last decade or so, this format is usually at an aspect ratio of 16:9. (16 units wide, 9 units high). If we want to go even wider (ultra-widescreen) then we should look at screen ratios approaching that of the cinema where screen ratios can be 2.3:1 or even 3.3:1. With a ratio of 3.3:1 a screen would be 3.3 times its height. ie 16.5m x 5m. If we were to try and reproduce a screen of this aspect and size with a single projector, as is done in the cinema, then we run into complications.... Usually when an image is enlarged there are two possible problems.
Problem 1:
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An XGA projector has a projection chip
that can display 1024x768 pixels
 (1a) The projection chip in a standard XGA projector has a finite resolution of 1024 x 768 pixels (a ratio of 4:3). A projected image measuring 16.5m across, would automatically have a vertical distance of 12.4m. Each pixel would measure approximately 1.6cm in width. |
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Cropping the image results in a vertical
resolution of only 310 pixels
(1b) For an extra wide screen, we could arrange to mask the top and bottom of the image, to make it have the correct ratio proportions for 16:9. However, only a very few of the chips vertical resolution can be used (310 pixels) which would result in a very low quality display. Note that even if this image could be increased in quality, if it was coming from a computer (by increasing the output to SXGA or UXGA), the projector will scale all inputs to its native XGA chip resolution. |
Problem 2:
The second possible problem that needs to be taken into consideration is that when projecting any images, as the projected image size gets larger, the amount of light needed to keep the screen at a constant brightness has to increase as well. The relationship between image size and screen brightness is an 'inverse square law,' meaning that as a screen image size is doubled, the amount of light projected on the screen has to be 4 times brighter. Quite simply, a screen that is 4m wide with a projector of 5,000 lumens will need 20,000 lumens if the screen width is increased to 8m. If the screen size is to be doubled again to a width of 16m, 80,000 lumens will be needed to make the image seem equally as bright as the original 4m wide screen.
Each projector displays 1024x768
portion of complete image giving a total
resolution of 3,072 x 768 pixels |
Joy’s is able to solve both of these problems with one simple solution. The use of multiple projectors with each projecting just part of the image.
This has two benefits:
(1) No loss of vertical resolution along with an increase in horizontal resolution.
(2) Each projector is only projecting part of the screen image therefore the brightness is not affected with increasing screen widths if the height is kept the same. |
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