How to overlap & feather two tracks

johnmeyer wrote on 11/19/2014, 7:03 PM
I was given a film transfer with bad registration. Here is a sample frame:



I want to take the bottom of this frame and join it back to the top, where it belongs. Up to a point, this is simple: I duplicate the track, and then use pan/crop or track motion so the track on top only has the video from the bottom of the frame, and this video is now placed at the top of the track. I then move the main video down so the bad registration is moved off the screen.

This is the result:



As you can see, I need to somehow create a blend/blur between the two edges. It seems like Vegas should be able to do this, but all I can come up with is using a mask. This doesn't work because it diminishes the edges, which actually makes the line between the two videos more apparent. What I need is something that will both enlarge and also overlap, but only along the horizontal line between the two videos, and only for a small number of pixels.

Any ideas or suggestions?

Comments

Tim L wrote on 11/19/2014, 7:14 PM
No suggestion to fix the blend, but shouldn't the little piece at the bottom be added to the top of the [I]next[/I] frame? i.e. Shift the "top sliver" timeline to the right one frame, relative to the main event. (Maybe you already did this but didn't mention it, or maybe I'm totally wrong about this...)
riredale wrote on 11/19/2014, 8:35 PM
The "next frame" comment is a good one.

Also, I think this will be very difficult to do, because there is no shared information between the two mating images. But perhaps a very slight vertical stretch just at the edges would allow for a very slight overlap and thus no darkening, though the image will look a bit confused with interlace-like doubling on some images.

Back in the early days of HDTV one of our competitors (NBC/Sarnoff Labs in Princeton) proposed a two-channel NTSC-compatible system that used a second channel to carry the sides of the widescreen HD image to be married to a 4:3 center image carried in the first channel. Never got rid of the banding, and they worked hard at it.

Also I think there will be some nonlinear optical artifacts from the fact that one edge was from the top of the frame and the mating edge came from the bottom of the frame.

Maybe better to just cookie-cutter a bit or zoom in a bit.
johnmeyer wrote on 11/19/2014, 9:52 PM
shouldn't the little piece at the bottom be added to the top of the next frame?Yup. I forgot to mention that I shifted the top track by one frame. Good catch.

I don't think there should be any artifacts, unless the capture system had non-linear optics top to bottom.

I'll keep thinking about this. There has got to be a way ...