Now the wall surface is as bright as our projector can go and there really is no space for a black level - our projected image, even if its pure white snow - probably isn’t visible at all at this point. Let’s open the window in the room and raise the brightness to 1000 lux. Now our black level on our surface area is starting at 250lux and our white is still at 1000 lux - our contrast has gone down and the image is starting to look pretty washed out. Now, lets turn the lights on in this room and pretend we just bumped up the ambient lighting in the room to 250lux. This gives us a good contrast ratio to show all the colors between black and white in a dark room. If we have a 1,000 lumen video projector covering a square meter of surface area (not a very big surface), lets say our black level is 0 lux and our brightest white is 1000 lux. IndoorsĪlright - with that out of the way. In short - measuring brightness is complicated and we’re drastically simplifying. (btw Medium renders a zero and lower case O the same…weird…o0o0o0o0). ![]() Finally, most projectors can’t project a pure black and don't actually go from 0 lux to full white in a pitch black room. Full color images will potentially need even more light to appear vivid than just black and white gradients. We can also assume we’re talking about black to pure white here as different colors have different perceptual brightnesses to our eyes. Secondly, projector manufacturers have pretty different standards on what constitutes a lumen (some follow a standardized ANSI lumen measurement). First, Projectors are typically made to project in a 16:9 aspect ratio which is going to make our calculation for lumens per square (1:1) meter a little more challenging, so since this is a hypothetical exercise anyway - we can just assume projectors are going to cover a square and not a rectangle. To get a few things out of the way first, there are several known things we’ll just make assumptions about, or leave out of our calculations. With these readings in hand, we can start thinking about how bright a projector typically is over a given surface area. Moving into the shade of a tree and getting indirect light was usually anywhere between 3,000–9,000lux. With my illuminometer, I was able to get a reading of anywhere between 90,000 and 110,000 lux on a bright sunny day in NYC in June. These light meters are mostly used in the photography industry, but they are useful in a lot of other areas as well, from horticulture, to museum lighting and others. I used an Illuminometer to see these for myself. To actually obtain these measurements, there are several tools available.
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