Ground Glass Grain

[Richard Mellor]

my first test shows promise need a better capture of the grain

[Brett Erskine]

Chris - great work! Let us know if it hold up to being put in motion and viewed on a TV screen. If so they question becomes does it help any to make your adapter oscillate? I know this method wont work on moving GG. What Im wondering is the quality difference between a shot with moving GG and one that you have the motor stopped and you try Chris' methods on that footage. My guess is the moving GG will be better but by how much? Perhaps it we wont have to move the GG anymore...I'm doubtful but then again we'll see.

So Chris is this process render intensive or will this be pretty eazy for us to deal with on full length projects?

[Chris Rubin]

Brett,

I'm sure that as far as gg grain is concerned, moving gg will always be better. But for me getting rid of the moving parts and the need to power them has been an important goal. Looking at stuff like 'Life without Memory' (enormousapparatus.com), I've come to a conclusion that artistic value of depth of field, if shot well, will overrun any grain problems, and if there's a way to minimize the gg structure to a point where it is almost invisible, that's good enough for me.

About the render time - it's pretty fast (less than 1s/f), so no problem there.

The motion holps up perfectly, because the only things that change are the non-moving elements in the image (static grain).

Another thing...
Dario Corno mentioned earlier the problems that could arise from the DV compression. He's got a point. I believe that in-camera processing (such as sharpening) could be more of a problem here although I did not see any of that come to play in the few tests that I did. I'm looking forward to trying this approach with Juan's Andromeda. As it has a resolution that exceeds HDV and 12bit output, the gg grain should be resolved much more accurately and thus should be more easily sampled and removed.

[Richard Mellor]

this sound cool. so the higher the rez the more you will see the grain to sample it out . plus the precision to make a ocillating adapter is beyond most of us here. I think the total parts list for a static adapter is under $150. with the chris rubin workflow this
may be enough for most members.

[Aaron Shaw]

very interesting Chris. Do you have some footage you could post?

[Richard Mellor]

a thought just occured to me. if we were to attach the static adapter to a 35mm slr camera ,and get a super sharp picture of ground glass we are using. we could make this way better than high def. It sounds like the goal is to get the best possible sample of the grain pattern from our ground glass.

[Frank Ladner]

Hrm...

You would have a high-rez picture of the ground glass, with all the grain detail...but when you applied that back over the low-rez (720x480 SD) footage, it would possibly re-introduce grain into the footage. Some of the finer grain that wasn't picked up originally in the footage would be put back over it and it wouldn't really cancel out.

Or...maybe it would work. Just a thought.

[Aaron Shaw]

I'd have to agree with Frank. I'm not sure we need anything higher res though. We can only record so much res so capturing - and removine - more detail than exists in the original would probably be a bad idea.

[Richard Mellor]

then maybe a non compressed raw digtal photo.

If the dv compression is a problem

[Chris Rubin]

higher rez capture of the grain will not help. The grain capture method has to be as similar to the actual footage capture as possible.

It is true, that higher rez 'noise print' would be more accurate, so this looks to be something for HDV. Although MPG compression creates artifacts during fast movement, which will not be there on the grain pattern. So it seems that for static noise removal HDV can be both good and bad.

The best results obviously come from uncompressed / mildly compressed footage, which we cannot get yet.

Chris

[Bob Hart]

Chris.

With the night-vision, I have a process I use which limits but does not entirely eliminate the scintillation noise in the relayed image.

I call it layer stacking though I think frame blend in After-Effects amounts to the same thing.

Basically, scintillation noise endures for only one frame or so. If one makes multiple copies of the footage and offsets them successively by one frame on the timeline and assigns them an equal transparency which is a division by the number of tracks of 100%, then individual defects in the blended frame are less apparent. The downside is a smearing effect on movement. - However ----

To make up a valid mask relatively free of camcorder noise and compression artifacts unique to individual MiniDV frames, this method may be helpful. Movement is not an issue. The only granular "noise" of note will be the groundglass grain itself which is exactly as we want it, dead still. Let's say blend ten frames at 10% transparency then any other noise on individual frames will be effectively eliminated.

This process is also useful to reduce low-light gain noise in conventional video imaging.

There's one issue with your process which would be easily resolved with regular good housekeeping. Best practice will be to shoot a short gray-scale for every setup or less thoroughly, perhaps after each unpack, transport or dismantlement and re-assembly of the ALDU rig to the camcorder to allow for slight departure of the grain texture from the reference gray-scale between shots. If shot on each setup, that gray-scale might also be accurate for the color environment of that shot

[Matt Champagne]

Has anyone tried, or do you think you could do a simular process using multiple video tracks in vegas? You could at least see your results without having to wait for AE to render.

[Jim Lafferty]

I'll be trying in Vegas once I get my wax adapter done, which reminds me...*goes and sets the oven to 450*...

- jim

[Bob Hart]

Furthur to above, I have been doing this "layer-stacking" in Premiere 6.

There's one small wrinkle, you have to create new tracks and use those, not Track2, 1A or 1B, otherwise the transparency thing doesn't seem to work. I am probably mismanaging the software. There is likely a keystroke method of achieving the same outcome but I have not gone searching for it yet.

It was a bit of a hit and miss guess for me as I used the "rubber bands" and on the small display, 20% transparency for five tracks is a little difficult to get exact. In practical terms, it doesn't matter a lot.

Another means of doing this for a single frame would be to export several consecutive frames and layer them in Photoshop, or Ulead, or similar.

In Ulead, I used a slightly different method to create an individual demonstration frame. I used the "Edit" "Stitch" functions on five frames, merging each new frame back onto the previously merged and saved frames at 50% transparency until I got to the last frame and set that one alone at 20%. You have to save each successive stitch as a new file and close each previous donor file before moving onto the next.

[Jim Lafferty]

Jesus. That sounds like a real digital workout :)

Vegas allows track opacity to be set several different ways -- you can type the numbers in manually, use rubber bands, pull levels, etc.

I'm going to have to do some research to properly understand Chris's method, but Vegas should get the job done. I'll have my tutorial up sometime first week of January (given the holidays and all...)

Speaking of holidays, I hope everyone here is in good health and I wish you all the best in the coming year -- and beyond :)

- jim