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Shooting old monitor (getting rid of moire/ aliasing)


Bradley Roberts

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I had a couple insert shots of LCD screens in our latest project and the aliasing was pretty strong. I really found no good way to remove it, and decided that it was better to see it and leave the impression that we were really looking at an actual computer screen.

 

We have other shots in the film of TVs, but these are VFX composites, and don't show this issue.

 

But, from my experience, if you're shooting a TV in the background with a live image on the screen, you won't see the aliasing, unless you shoot a closeup of the display. If you do shoot a closeup, it's easy to replace the screen image on the display in post with the original footage. Unless, like us, the insert is of someone actually typing on the display. If that's the case, this becomes a VFX shot to record the computer work to a file (instead of a live shot) and then insert that into the display in post.

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  • 2 weeks later...

If you want to go with live display, you could try to defocus the LCD screen by cutting a piece of lighting tracing-paper diffuser to screen size and oiling it with barbecue spray or spraying hair spray on the textured face of the tracing paper to make it more transparent. You may of course still get screen-refresh artifacts. There may be other ways of doing this which are healthier for the LCD display you are putting it on, - oily side not touching the screen of course. You will likely need to use a spray. Wiping or brushing will leave bands and streaks. My personal preference would be to put a paper chromakey green mask on the display and adding the screen vision in post. With older curved CRT displays, it becomes a bit trickier to get a good lay up of a paper mask. I have had adequate but not best results using spray-on contact adhesive on a CRT screen then laying up a piece of carefully precut green pooltable felt cloth which has been lightly pre-sprayed with the same contact adhesive. You need to let the adhesive dry to be as tack-free as possible because you need to interpose a large piece of paper between the cloth and the CRT screen and carefully ease it out as you firm the cloth down to the CRT screen's curved glass surface. You most likely will still have to trim the edges. With care you should be able to "walk" any wrinkles out and not have to lift the cloth. Lifting the cloth will stretch it uncontrollably and you may have to start over. Please take the advice of others with more valid comments to make than mine

Edited by Robert Hart
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