Projector Specs
- Thread startermetti
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A built in shutter doesn't help with projection mapping since I need the projector to be projecting images in some spots while looking as close to black as possible in others. I have access to dousers when I need them but that isn't helpful in these situations.
Usually you are looking at contrast levels in the specs, and adjusting the settings so that the projected "black" matches the ambient light level. what color are the objects that you are projecting on to? will the projected image including the black areas totally cover the object or are you going to have some areas that are not covered.. If the image being projected on to is NOT black, then usually the color being reflected back to the viewer masks the "black" being projected.
Be aware that if you crank up the brightness inorder to max the lumens on the projector, your blacks will become more gray, so basically work with a projector that is high lumen level that you normally would need, has a good contrast level, and play around with the settings and if you can use a object color that is not black that helps
Sharyn
There are several potential factors in what defines the black level on the screen including is the contrast ratio of the projector, the ambient light levels and the projection surface.
What do you consider a dark environment? The Digital Cinema Initiative 'Digital Cinema System Specification' specifies maximum ambient light levels off the center of the screen with the projector off or lamp doused of 0.03cd/square meter or 0.01ftL for theatres and 0.01cd/square meter or 0.0029ftL for mastering environments. It also specifies a center screen measurement at the reference viewing location of 48cd/square meter or 14ftL for the projected image (+/-0.7ftL for mastering facilities and +/-3.0ftL for theatres) with 70%-90% of that value allowed at the corners and sides. That's a 1,400:1 (1,100:1 to 1,700:1 range) full on/full off contrast ratio for theatres, so that could be seen as a guideline for desired projector contrast ratio.
The underlying point here is that unless you have extremely low ambient light levels or an extremely bright image, the contrast ratio of many current projectors projector is likely not going to be the limiting factor in the image black level.
What do you consider a dark environment? The Digital Cinema Initiative 'Digital Cinema System Specification' specifies maximum ambient light levels off the center of the screen with the projector off or lamp doused of 0.03cd/square meter or 0.01ftL for theatres and 0.01cd/square meter or 0.0029ftL for mastering environments. It also specifies a center screen measurement at the reference viewing location of 48cd/square meter or 14ftL for the projected image (+/-0.7ftL for mastering facilities and +/-3.0ftL for theatres) with 70%-90% of that value allowed at the corners and sides. That's a 1,400:1 (1,100:1 to 1,700:1 range) full on/full off contrast ratio for theatres, so that could be seen as a guideline for desired projector contrast ratio.
The underlying point here is that unless you have extremely low ambient light levels or an extremely bright image, the contrast ratio of many current projectors projector is likely not going to be the limiting factor in the image black level.
It varies but examples of current projects includes masked/warped/cornerpinned projections in a nearly pitch black theatre. The projections that are supposed to be visible are on a matte white painted surface and the rest of the projection that I am hoping to make as invisible as possible is either on a dark gray marley or a black commando drop. Another current project has projection onto a sidewalk in an urban street-lit area after dark.
That is in line with what I already thought from personal experience. I recently programmed media for a show that used a mix of LCD and DLP projectors and the DLP units were noticeably better in this regard. I also have a couple small (2.5k lumen) projectors and the DLP unit is definitely a better video black than the LCD unit.
That's probably a little overly broad generalization as there is a range on both types of projectors and even changing the color wheel on DLP projectors, some projectors come with more than one color wheel, can affect the black level and contrast. While DLP projectors typically have had an advantage in black levels and contrast and LCD projectors an advantage in color rendition, the differences in both cases have significantly decreased as the technologies have improved.
Along the same lines, while you asked about projector specifications, you also noted that the concern was about when part of the image is black and other parts brighter. That means the issue is not simply how black or how bright the projector can be but rather what range it can support at the same time. This means that full on/full off contrast ratios are not directly relevant and ANSI checkerboard contrast ratios are probably much more applicable. Just FYI, a trick that can be used to increase the published full on/full off contrast ratio values for DLP projectors is to measure full black with a 'high color' color wheel and then measure full white with a 'high brightness' color wheel or even the color wheel stopped on the white segment. That does reflect the maximum and minimum output levels but you'll never get that contrast ratio in real use. A less devious but similar aspect applies to any ratings for DLP projectors with multiple color wheel options as one has to be sure that the brightness and contrast values specified are with the same color wheel, it's not really unreasonable to specify the projector brightness using a 'high brightness' color wheel since that is what someone concerned primarily with brightness would likely use but to specify contrast ratio based on a different color wheel, however the two are not necessarily achievable at simultaneously since they are based on different conditions.
However, the general point of black levels of different projection technologies actually goes back to my earlier point that with many more recent projectors and a reasonable image brightness for the applications noted, one would need to have very low ambient light levels on the screen for the projector black level to be the controlling factor in the image black level. Just for reference, some sources I've found suggest 10,000+fc for direct sunlight, 1,000fc for daylight, 100fc for outdoors on an overcast day, 50-100fc for classrooms, 30-50fc for task lighting, 1fc for twilight, 0.01fc for a full moon and 0.0001fc for starlight (a footcandle is equivalent to a footlambert). You may be able to get those low levels in some indoor situations but it would be very difficult to do in the outdoor urban setting mentioned.
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NickVon
Well-Known Member
Projection Screen by Screen Innovations - HD Projector Screen maybe something like this as a projection surface would be goodf or you, new tech and a little pricy?
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