Many of the recent projectors are employing this trick to get "blacker blacks" during playback.

I read that some are using a scan frequency of 60 Hz to, in essence, update "real time" with the demands of the displayed scenes.

I assume the iris' are mechanical. This means there is lag and I anticipate that this manifests itself in a "bobbing" brightness of picture during flashy scenes that go from one extreme to the other very quickly.

The question is: "Would it not be more efficient to include a stream on the DVD for the amount of light during the playback that is slightly ahead of the actual scene playback so the iris is not required to process this real time, but could simply "read" the upcoming requirements and adjust accordingly without processing it "on the fly"?"

Maybe I don't understand the dynamic iris. Please excuse me if I'm way off base here.

Some iris's work better than others, and Sonys is the best I've seen so far. operating at 60hz (if that's how quick it is) means that it's quick enough to trick the eye, in the same way as film makes us think still images are moving.

I remember Darinp2 suggesting an 'iris track' or flag to be implemented so that the source would tell the iris where to stop in it's range for each particular scene/image/frame, and I agree that seems to be a good idea if you want them to work optimally, provided that all pj iris's work the same way of course (so the end result is the same).

Gary

Many of the recent projectors are employing this trick to get "blacker blacks" during playback.

I read that some are using a scan frequency of 60 Hz to, in essence, update "real time" with the demands of the displayed scenes.

I assume the iris' are mechanical. This means there is lag and I anticipate that this manifests itself in a "bobbing" brightness of picture during flashy scenes that go from one extreme to the other very quickly.

The question is: "Would it not be more efficient to include a stream on the DVD for the amount of light during the playback that is slightly ahead of the actual scene playback so the iris is not required to process this real time, but could simply "read" the upcoming requirements and adjust accordingly without processing it "on the fly"?"

Maybe I don't understand the dynamic iris. Please excuse me if I'm way off base here.

That could happen, and may in some content. But just because it happens in realtime, don't assume that the Iris is "behind" the image. It should be quite simple for the DI algorithm to analyze a frame, determine the optimal Iris/gamma setting for that frame, and adjust the Iris simultaneously (or even before) putting that frame on the screen.

Basically the algorithm could delay the video to match the iris calculations. And in reality, there's probably no delay needed since there's already latency in the image processing (scaling) inherent in the PJ.

The 60 cycles really has nothing to do with the iris. It is a refresh rate for the panels. The new stuff coming with have120hz refresh rates.

Iris are very very fast. Just as in an automatic photo camera lens. Say the speed of your shutter being open is 1000 of a second. The mirror flips up, the iris stops down, the shutter opens, the shutter shuts, the iris opens up and the mirror comes down. In a camera this happens in 1/8 of a second or so. Irises move quickly.