Black level build up at the blend

[Lloyd Stewart]

What is the state of affairs as regards what David Branson used to call "black level build up", where if you go to black, there are darker shades of black where the blend is?

 

I happen to love to go to black, especially when it fits the emotion of a moment. It kinda gives people a moment to digest what they've just seen, right? Woody Allen used that "going to black" effect brilliantly in his movie "Manhattan", so I've come to appreciate how effective it can be at times. But it loses a lot of that effect when you see the different shades at the blend.

 

So I thought perhaps some solution may have been discovered by my fellow Watchout users by now? Any suggestions?

[Jonas Dannert]

Hi Lloyd,

 

Since black is "a little light" no matter with which technology you project with, it will always be a

"black level build up" in the blend area, there's no easy way around that fact. DLP technology is still

the preferred platform in this regard, I think. LCD technology:s black level is better these days,

but not on par with DLP.

 

There are of course ways to counter this issue, some more expensive than others:

 

- using special processors, that can raise the black level of the areas surrounding the blend.

Used in simulators and similar areas, often combined with warping tools etc.

One example can be Projectiondesign:s MIPS-boxes. This kind of solution is not cheap.

http://www.projectiondesign.com/products/multi-image-processor

 

- old school way, it's optical blending by placing masks, mechanical or optical, in the optical path of the projector/s.

This is a simple, in-flexible solution to the problem, but it will give you a complete "black" level.

Could be cheap, but not so easy or practical to implement/use.

An example : http://www.barco.com/en/simulation_virtualreality/product/1451

 

Hope this helps,

/jonas

[makkot]

To me the simplier way around: overlap by watchout and soft edge by projectors (means also removing blend curve in Wout preference). Christie and latest Panasonic has Black level Compensation in order to paint a uniform black on the screen, hiding the overlapping area to your eyes.

 

You just need a guy who can manage that process, but with professional projectionist i always achieved great results.

 

Regards

[Dimi]

Hi,

 

1)use a dark grey as background so that you can get rid of the hard overlapping in black. on most LCD projectors it won't matter, because they will always throw light.

 

2)I repeat: use projector's edge option in addition to watchout softedge

 

2)http://www.theblacky.de/

this will totally eliminate your problem and can easily programmed into watchout (via e.g. a 2-port-node or an enttec device). Best solution for every projection where you want real black (beside your projector has a real hardware shutter). If you don't know how to output DMX (or don't want do that for redundancy considerations) you can always use the button delivered with the blacky.

 

Dimi

[Lloyd Stewart]

Jonas, Makkot, and Dimi:

 

I hope you all realize how much your replies are appreciated. Excellent information.

 

I don't know what I'd do without this forum.

 

Thanks!

 

Lloyd

[Jonas Dannert]

Just to state the obvious, ALL projectors throw light when showing a black image.

 

LCD technology is inherently worse than DLP in this area, especially high-brightness ones. (that was you I meant, Sanyo... ;-) )

Color/brightness uniformity over the image area and using wide-angle lenses also affect this.

 

Using projectors with built-in edge blending capability, could be better,

if there is Black Level Compensation for the areas surrounding the blend.

One thing though, there will be a hard-edge issue between these areas, that has to be dealt with, too.

 

Only way to get a "real" black is, as suggested above, to use projectors with real shutters or external ones.

Nicest is to use a dowser/dimmer type like in Barco HD8, this gives you dimming instead of a straight cut.

Both ways will of course give you total blackout.

 

Good thing with WATCHOUT is, that these can be controlled from within a timeline, if needed.

[David Organ]

I have worked on two shows where the Blacky (http://www.theblacky.de/) or a very similar mechanical device was used on two XF47s. It was a great "Get out of jail FREE" card (Monopoly) when we were setting up during dress rehearsals with wrong MPEG encoding and lots of blue screens of Death! Watchout SO didn't like the encoding - a heart stopping day and the manual shutters were a real bonus. I just wish Watchout wouldn't waste time uploading an epic MPEG when it has no intention of playing it

 

Regards

David

[eameres]

Any reason Watchout couldn't have this built in?  I've used other software that had it and it was a HUGE help.  Basically it would raise the blacks in the non-overlapping areas to match the overlap.  It also had some geometric controls to get the bounding edges of the overlap just right.

 

Eric.

[rafalmysliwiec]

The best way for perfect black is the projectors shutter. I'd simply connect them to watchout switch with RJ45 cable and send "shutter close" command via TCP/IP output when picture goes completely black. Of course, if projectors allow for it.

[Jonas Dannert]

Any reason Watchout couldn't have this built in?  I've used other software that had it and it was a HUGE help.  Basically it would raise the blacks in the non-overlapping areas to match the overlap.  It also had some geometric controls to get the bounding edges of the overlap just right.

 

Eric.

 

 

And that software would then be...?

 

/jonas

[Mike Fahl]

I think you can do this already, albeit in a somewhat manual way. Try this:

• Make a 10% gray rectangle image (PNG), about the size of the none-overlap area, possibly with a very slightly feathered edge (one or a few pixels only), where the image fades to black. No alpha channel needed.
• Create an auxiliary timeline in the Task window that sits on top of all others.
• Add the above mentioned image to this Aux timeline, one for each non-overlap area. Scale and position the rectangle to eactly fit the darker area.
• Add a Color tween track, and use its Brightness setting to tone down the image so it's just bright enough to match the brightness in the overlap areas.
• Set the blending mode of each of those cues to "Lighten".

I haven't tried this myself, but I think it should allow you to get pretty close. At least it could provide a way for further exploration of this idea. Let us know how this works out.

Mike