Chroma Key...detection of, video forensics

Posted: Wed Sep 12, 2007 8:43 pm

Is there an easy way to detect if a video has been manipulated using blue screen (or green) ?

This would be of amateur videos found on the internet, of unknown:
* origin
* number of times it may have been compressed/decompressed, and method (lossy or lossless)
* original file format.

thanks.

=RR=

Posted: Thu Sep 13, 2007 12:09 am

redrabbit, badly set up chroma keys, generally look obvious. Silvery outlines. Strange shadows. Look through eyeballs! Good chroma keys require very careful lighting and proper exposure. There are however some newer chroma keying software, such as, serious magics sale to Adobe, of their unique vector keying. This new style of chroma keying, known as vector keying, includes virtual sets and digitally manipulated camera moves and zooms in concert with specially designed virtual sets. These look fabulous! It is not plagued by common chromic key problems. And so good chromic keys can be quite deceptive when done well. Cable TV/cable access TV only knows how to do horrible looking chromic keys. Blah. Phony! Look into Adobe's Ultra Key. It's fabulous and I believe costs just under $500? Other virtual sets are extra but are not necessary. I have seen this product demonstrated numerous times that digital video conventions. A truly wonderful 20 minute demonstration that is well worth seeing twice or more? I want to get it at some point?

Remember, no blue or green shirts or sweaters. Unless you want to do a segment of the invisible Man/woman?

I'm really not hear
Ms. Remy Ann David

Posted: Thu Sep 13, 2007 12:11 am

redrabbit, badly set up chroma keys, generally look obvious. Silvery outlines. Strange shadows. Look through eyeballs! Good chroma keys require very careful lighting and proper exposure. There are however some newer chroma keying software, such as, serious magics sale to Adobe, of their unique vector keying. This new style of chroma keying, known as vector keying, includes virtual sets and digitally manipulated camera moves and zooms in concert with specially designed virtual sets. These look fabulous! It is not plagued by common chromic key problems. And so good chromic keys can be quite deceptive when done well. Cable TV/cable access TV only knows how to do horrible looking chromic keys. Blah. Phony! Look into Adobe's Ultra Key. It's fabulous and I believe costs just under $500? Other virtual sets are extra but are not necessary. I have seen this product demonstrated numerous times that digital video conventions. A truly wonderful 20 minute demonstration that is well worth seeing twice or more? I want to get it at some point?

Remember, no blue or green shirts or sweaters. Unless you want to do a segment of the invisible Man/woman?

I'm really not hear
Ms. Remy Ann David

Or here.

Posted: Thu Sep 13, 2007 9:55 pm

Thanks Remy.

Yes, I've seen bad keying before....eechhh.

I am referring to a high quality pro job of inserting images, that cannot be determined by eye.

I've worked in front of the camera setting up these shots, on big budget films, but not behind the camera, in the editing room.

Let's say there are two images keyed together, one background, one foreground, and this image is meant to be real, but is really a hoax...as in UFO videos.
I've read that if the resulting image is copied in a lossy format, multiple times, one of the two might show different pixelization than the other, as generations are created....therefore allowing you to determine there is indeed keying (multiple images)...and the video is a hoax/fraud.
-------------------------------------------------------------

I'm a little embarrassed as to why I'm asking this.....

I have a friend who is trying to convince me the 911 terror attack is fake, and airplanes and explosions were added and deleted using bluescreen technology to cover up a missile attack.... on ourselves. Laughing

I am trying to show him he is wrong, and a kook, and want to show him why.
I know.... his whole argument falls apart if reality is factored into his equation. This is a big topic among the perpetually suspicious, and YouTube is full of this conspiracy crap.

=RR=

Posted: Tue Sep 25, 2007 6:09 am

Back in the "olde" days when I first got into television we used blue screens not green. The chroma keys were blotchy and had all of the bad effects as described by Remy. I was at a studio yesterday and the the guy who was showing me around is a good friend. He is also running a small INTERNET channel where he does Christian related talk shows. He is running this on a very small budget. He uses virtual sets and chroma key to make his productions look VERY professional. He showed me how he does the chroma keying and puts himself and a guest into the virtual set. To say I was impressed would be a understatement. The keying looked great and there were no visible artifacts. This was all done in his home computer with a five hundred dollar program. I can't imagine what a full blown studio today could produce given half a chance.

As to your"problem" with your friend the conspiracy theorist. Don't even try to convince him because he will think you are "part of the conspiracy" it is like the people who try and try to convince everyone that the astronauts did not really fly to the moon but instead were in a Hollywood studio and it was all made up and the "cast of thousands" was all paid off or told to shut-up or they would be killed. There are so many of these conspiracy theories floating around from JFK to the attacks on 9/11 and that there was no plane that hit the Pentagon and that there were explosives stored in the WTC for some "unknown" reason and they are what brought down the twin towers not the crash of the airplanes. It is like trying to convince an Atheist that God does exist. Save your breath and don't waste your time.

Posted: Tue Sep 25, 2007 7:28 am

redrabbit wrote:

I'm a little embarrassed as to why I'm asking this.....

I have a friend who is trying to convince me the 911 terror attack is fake, and airplanes and explosions were added and deleted using bluescreen technology to cover up a missile attack.... on ourselves. Laughing

I am trying to show him he is wrong, and a kook, and want to show him why.
I know.... his whole argument falls apart if reality is factored into his equation. This is a big topic among the perpetually suspicious, and YouTube is full of this conspiracy crap.

=RR=

Hmmm....well, if your friend needs a little help from an eye witness....

I work in the Pentagon and have since early 2001. I was running late to work on the morning of 9/11 (thankfully since many of my coworkers in my office are no longer alive).

As I was coming into work about an hour or so late, I watched as the plane smashed into the side of the building. The explosion which occured about 100 meters away cracked my windshield and melted limestone was deposited all over the hood and roof of my car.

I can assure him that there was in fact no green screen behind the building that day.

Posted: Sun Sep 30, 2007 12:26 pm

Actually this is kinda for Thomas. Thomas - just curious, what did your friend use for lighting? I need to buy some for the same process and want, as always, good, yet inexpensive.

(Holy crap, Cucco! What a terrible, amazing story.)

Posted: Sun Sep 30, 2007 1:05 pm

This is what he is using.

http://www.imagewest.tv/index.asp?PageAction=VIEWPROD&ProdID=71

Please note that the model is NOT included in the purchase price.....<GRIN>

Posted: Sun Sep 30, 2007 2:40 pm

Cool, thanks!

About the model, that's OK, my wife wouldn't let me keep her anyway...

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