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OK, it looks like the pressure is on for me to finish my gray screen analysis.
No, I'm not so vain or arrogant to believe that everyone wants me to do this. I've just recognized that there is a lot of misunderstanding, and a lot of misconceptions, about the theory behind gray screens and how they work in practice, and I think I've got enough of a handle on it that I can do justice to the task. In fact, this article will address some misconceptions that I've held myself in the past.
Allow me to give you a brief preview to whet your appetite. Here is a two-sentence summary of my article:
Quote:
And here is a list of some of the common beliefs about gray screens that I intend to address:
Please do not hesitate to suggest what else I should include. I hope to finish by the end of the weekend.
No, I'm not so vain or arrogant to believe that everyone wants me to do this. I've just recognized that there is a lot of misunderstanding, and a lot of misconceptions, about the theory behind gray screens and how they work in practice, and I think I've got enough of a handle on it that I can do justice to the task. In fact, this article will address some misconceptions that I've held myself in the past.
Allow me to give you a brief preview to whet your appetite. Here is a two-sentence summary of my article:
Quote:
The primary purpose of gray screens is to trade reduced brightness for increased intra-scene/ANSI contrast by suppressing secondary reflections. Gray screens cannot improve on/off contrast, and in practice are not effective for combating ambient light problems. |
- Using a gray screen is just like using an ND filter. False. ND filters darken the image like gray screens do, but they do nothing to suppress secondary reflections. In fact, in ambient light, an ND filter makes on/off CR worse, and gray screens do not.
- Using a gray screen is just like wearing sunglasses in your home theater room. False. This is commonly stated as a reason not to use gray screens, but in fact they actually accomplish something that sunglasses do not: improve ANSI contrast.
- Gray screens improve on/off CR. False, with one very technical exception.
- Gray screens improve absolute black levels without compromising white levels. False (this is just another way of writing the last statement).
- Gray screens improve instantaneous contrast; that is, the contrast observed within a single projected image. True. In fact, this is why letterbox bars get darker, which people often misattribute to improved absolute black levels.
- Gray screens cause color shifting. Not necessarily. Perfect gray screens do not shift colors. Gray screens can, but hey, so can imperfect white screens.
- The Firehawk has a gain of 1.35, and the StudioTek has a gain of 1.3. So the Firehawk has all the benefits of a gray screen without sacrifice. False. Unfortunately, contrast enhancement is not free. In this case, the cost is a reduced viewing cone, increased hotspotting. For good reason, some say that the Firehawk has a "useful" gain of 1.0.
Please do not hesitate to suggest what else I should include. I hope to finish by the end of the weekend.