Key difference technique-Look at the results!

johnmeyer wrote on 3/9/2006, 9:14 PM
Thanks to all that helped me with this. Here is the result:

Happy Birthday Idol

Remember that the video was amateur footage, with lousy lighting (I had to alter his exposure a LOT), auto exposure, auto-focus, etc., and no green screen. It was just a plain background in his house. However, with all the help you guys gave me, I ended up with a pretty good key and, by keyframing some of the elements of the masking tracks, was able to minimize the need for garbage masks, although I still needed to use them in a few places where the background would have otherwise come through his teeth.

Also, this was for his own private use in his home with friends and family, and he loaned me his American Idol DVD, so I think we were well within fair use of the copyrighted material. (And I did it for free, for an old friend). Since he didn't script this, I had to find reaction shots that made sense, and I also had to find sounds to mask the fact that the audio was so different between his video and the pro stuff, and also, their audio had music underneath at times. I would have loved to have had a set of soundbed CDs, but I found a few things in the ACID loops that worked OK.

Comments

Grazie wrote on 3/9/2006, 10:21 PM
JOHN! Enough with the techie reasons already!!

I loved it! It was funny and I bet the recipient adored it! Great stuff . .and yes I can poke about at it . .but I WONT!!

Loved it as it kept the Pop Idol "cringe" factor relevant and the "gag" still going . .and THAT'S what it was meant to do!

Loved it.

Grazie
apit34356 wrote on 3/9/2006, 10:57 PM
Very funny. Grazie review was right on! Your friend was great!
johnmeyer wrote on 3/9/2006, 11:09 PM
and yes I can poke about at it . .but I WONT!!

Thanks for that. I only had 24 hours for not only this, but the other nine minutes of slide show, video tributes, etc., which included lots of noise reduction, motion stabilization (I think people purposely move the camera -- no one can really be that bad) and more.

Yes, the key is really bad around his dreadlocks, but it was way too much work to either matte that out or use a secondary matte, or work more on the keyframing. The difference technique definitely has a few limitations. However, I was very pleased with how clean the main edges looked, given the poor lighting in the original, and the constant variation in exposure due to autoexposure which, of course, made the difference mask go nuts. Hats off to the Vegas engineers for building a product that can do all this amazing stuff.

farss wrote on 3/10/2006, 12:00 AM
A great effort considering what you had to start with. Now imagine how powerful this technique is with 4:2:2, good lighting and a motorised dolly.

Bob.
Grazie wrote on 3/10/2006, 12:07 AM
Sometimes, just sometimes, less than "perfect" stuff has a joke/ironic value to it too? Remember that.

Hmmm... a motorised Dollie? Now THAT would be something to video!

Grazie
farss wrote on 3/10/2006, 1:42 AM
One of our clients has a home built one he uses to shoot stage productions, damn clever idea, thhe camera is almost hidden behind the footlights and I'd imagine he gets some great shots.

But for compositing what you need is repeatable camera movement.
Again that's not quite as hard as you might think, a few years ago I builts some robotic test equipment, just stepper motors driving zero backlash lead screws and linear bearings, almost all the bits came from Radio Spares (that should get you going Grazie).
That relatively simple rig gave me amazing repeatable accuracy, down to 1/000th of a millimeter from memory. Whole thing was driven by a simple BASIC program from a serial port off a PC.

Bob.
Jay Gladwell wrote on 3/10/2006, 2:51 AM

That was funny! I'm sure he and his family will get a kick out it.


DrLumen wrote on 3/12/2006, 1:46 AM
Lol. Good job! I'm sure your friend will have a lot of fun with it.

intel i-4790k / Asus Z97 Pro / 32GB Crucial RAM / Nvidia GTX 560Ti / 500GB Samsung SSD / 256 GB Samsung SSD / 2-WDC 4TB Black HDD's / 2-WDC 1TB HDD's / 2-HP 23" Monitors / Various MIDI gear, controllers and audio interfaces

dibbkd wrote on 3/12/2006, 4:40 AM
That was hiliarious!

Where'd you get the American Idol background curtain image your friend was green-screen'd onto? I'd love to spoof something similar myself!

Edit: Ah, you must have taken a still real quick before the contestant walked out?
Spot|DSE wrote on 3/12/2006, 6:47 AM
If you read the original post again, you'll see that a DVD from the American Idol collection was used to rip the show, giving John the portions he needed to make a new show.
johnmeyer wrote on 3/12/2006, 7:08 AM
Where'd you get the American Idol background curtain image your friend was green-screen'd onto?

As Spot says, I just took a frame from the DVD with another contestant singing. I used that static scene and just airbrushed out the other contestant. I did a pretty good job of fauxing in (if that's a proper phrase) the word "Idol," but if you look at the word "American" you can see that the letters are all garbled. I'm sure no one noticed.
kentwolf wrote on 3/12/2006, 11:33 AM
>>...by keyframing some of the elements of the masking tracks

Did you use Bezier masks?

>>...able to minimize the need for garbage masks

What do you man by "garbage masks?"

Looks great. Just curious as to the precise technique.

Thanks!
dibbkd wrote on 3/12/2006, 1:11 PM
As Spot says, I just took a frame from the DVD with another contestant singing. I used that static scene and just airbrushed out the other contestant. I did a pretty good job of fauxing in (if that's a proper phrase) the word "Idol," but if you look at the word "American" you can see that the letters are all garbled. I'm sure no one noticed.

Hmmm..... sounds like it actually took a lot of work to get the American Idol stage background for your friend.

I would have thought there would have been even 1 or 2 seconds of video of the empty stage before the "real" American Idols walked out that you captured that frame, and had that for the background.

Even after reading "how" you did it, I don't fully understand, but have a pretty good idea.

Anyway, you did a great job, and it was very, very funny!
johnmeyer wrote on 3/12/2006, 5:43 PM
Hmmm..... sounds like it actually took a lot of work to get the American Idol stage background for your friend.

Actually, this was by far the easiest part of the project. I spent less than one minute doing this. You just use the "clone" tool in your photo editing program. Very easy.
FrigidNDEditing wrote on 3/12/2006, 6:34 PM
Turned out VERY good for no screen etc... - it's a nice tool isn't it :)

Dave
johnmeyer wrote on 3/12/2006, 8:41 PM
...by keyframing some of the elements of the masking tracks ... Did you use Bezier masks? ...able to minimize the need for garbage masks ... What do you man by "garbage masks?"

First, the original thread on this is here:

Help with difference key technique

This is where I asked for help, and various people gave me things to download and try. While the general idea of the technique is straightforward (you create a mask based on the difference in luma thresholds between a static scene -- which is the scene before any actors enter -- and the scene with someone present. Every place there is a difference in value, there must be something "new" in the scene, and the mask acts like a blue or green screen and lets the lower tracks show through.

However, if something on the actor's skin or clothes happens to be exactly the same value as the backdrop, things can show through. To minimize this, you apply the median filter which blends adjacent pixels so that you don't get little "pinpricks" of background showing through. Unfortunately, once in awhile, depending on all the settings, you may get certain areas showing through, similar to what happens if the talent wears a blue tie in front of a blue screen. To remove this, you add another track, with a duplicate of the background (or a duplicate of the foreground, depending on whether you are trying to add or subtract from the mask), and then draw a quick and dirty Bezier mask in the areas you want to affect, in order to eliminate the "garbage," hence the name. Since the edges of the key are usually just fine, you don't have to be precise at all with the Bezier mask, as long as it does its job and doesn't overlap the boundary between the background and the foreground.

For instance, in my project, the talent's teeth were similar to the background and sometimes the red of the American Idol logo popped through. I simply added a track above everything else, put a duplicate of the video on that track, and added a Bezier mask that was large enough to cover his mouth, but not so large as to extend beyond the head. As long as it covered the mouth, nothing popped through. I had to keyframe it. When I got to the parts of the video (most of it) where, because of lighting changes, etc., the video was no longer popping through, I removed the mask so I didn't have to keep keyframing it to keep it roughly over the mouth. Again, this "garbage" mask is only being used to fix up the mask. Therefore, if the mask generated by the difference tracks is already doing its job, the manual Bezier mask does absolutely nothing.
LyricsGirl wrote on 3/13/2006, 1:25 AM
Excellent work.....pity you didn't key out Simon......or at the very least substitute someone else.for him...:>)