video editing

[hardwareuser]

Is there a video program that lets you change all that does not move through the portion of a clip, and therefore let you change the background of the video or something?

 

[gsellis]

Explain this better. What I think you are saying is that you have a clip with a static background and you want to replace it with another. If so, you are not going to like my answer.

The answer is yes, but involves frame by frame keying. In fact, the easiest way is to export TARGA frame by frame and use the magic tools in PSP or Photoshop and save the alpha channel. Then reimport and use key editors. After Effects and Boris probably do it too. I can also do it in my editor, but it is frame by frame. This is not easy.

Unless someone else knows an easier method?

 

[hardwareuser]

Oh wow, that's very tedious. Thanks for the reply.

 

[Bglad]

I'm sure there are others that do it but I happen to have Adobe Premiere and Avid Express Pro and both will do it.

They work just like using chroma key except rather than just chroma green, they will let you adjust what color and width of the color band you want to cut out.

I've never really used it but toying with it tells me that it will not work well unless your background is a fairly solid and unchanging color and nothing in your foreground uses anything too close to the background color. i.e. shoot in front of a chroma background but don't shoot outside and expect to be able to remove the background with much success.

You may not like my answer when you see what these two pieces of software cost. I've not seen this in any of the more price friendly software packages.

 

[hardwareuser]

Thanks for the info. I guess it's like how they edit the movies, when they have those plain green backgrounds.

 

[gsellis]

Originally posted by: hardwareuser
Thanks for the info. I guess it's like how they edit the movies, when they have those plain green backgrounds.

Yes, they use blue or green screens, or even add green material. Most of the big pics will use bluescreen in a sound stage and then key in the background. In The Lion, the Witch, and the Wardrobe, the characters such as fauns and centaurs wore green (chromakey) pants that the digitially keyed in the rest of the character such as the lower half of the faun. Oh, and chromakey green is 0,255,0 RGB. To do it well, it must be well lit. Even then, we have tools to help smooth the shadows and "spill kill". Spill is where some of the green reflects onto the character or object and would get picked up by keyer in the editor. CORRECT lighting can fix a lot of that. That is why experienced Hollywood lighting guys get paid fairly well and get good credits.

So, an non-homogenous background can't be keyed out automagically. If you had a person in front of something like trees or grass, I would take my wacom pen and start tracing the edges carefully to create a mask. I would then dump all but what was in the trace area. Takes awhile, but there have been parts of film done like this before. Effects departments have done this in the past and will do it in the future. Wires have to be removed in some cases.

 

[gsellis]

Oh, I forget the name of the movie, but Keeanu Reeves is in a new movie that does sort of the reverse. They shoot the whole thing in Digital Video. They are now using "rotoscoping", which stated simply is drawing over a frame or picture, to make the whole picture as a charcoal or painted movie. I have seen some frames of it one of my videography mags. Looks kind of cool. Looks don't mean that it might not suck, but it was definitely a cool technique (and has been done before, but not for a full length movie from digital video.)