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Old 1st September 2019, 15:43   #3  |  Link
johnmeyer
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Join Date: Feb 2002
Location: California
Posts: 2,691
Interesting work. Thanks for doing that.

I've spent a lot of time using Delogo inside of Virtualdub, and even created a YouTube tutorial for it:

Tutorial on Delogo

I did that tutorial in response to a long thread about how to eliminate a sensor defect from a camera. This is a considerably easier job than logo/bug removal and one that Delogo was able to do with near-perfection.

I have not used any AVISynth logo removal tools, but I have used all the features of Delogo, including training it for removal of semi-transparent bugs, and specifying frame ranges for TV shows where the logo comes and goes, or moves around.

For me, the biggest need in advancing the state of the art is the blending algorithm. When the background is uniform and dark, such as the edges of a stage performance where the talent is brightly lit, but the wings of the stage are dark, the removal can be perfect. However, if the video was shot outdoors in the daylight, and the camera pans, you can get some pretty annoying results. For some videos, I just give up and leave it as is because the artifacts from the removal are worse than looking at the bug.

The problem is that the inpainting is nothing more than a blur function.

I know nothing about the technology of the existing AVISynth DLL you are using because I haven't used it, but the example above of the "Hawe Knho" shows the Inpaint blending looking pretty similar to Delogo. This is not meant as a criticism, but instead as a way to lead to my main question:

Is there a reason why I would want to use this instead of continuing to use Delogo? What are its advantages?

I am always looking for something that works either better or faster. Delogo is plenty fast, and it is also easy to use because it lets me tune the mask parameter interactively using the VD "preview" display. I want something that can make the logo disappear, with almost no residual evidence that it was there.

Is this possible?

I think it might be. If I were going to do development in this area, I'd look at how RemoveDirt does its painting. I just did a restoration of one of the most spectacularly degraded movies I've ever dealt with, a one-of-a-kind 16mm print of a 1963 AFL football game. It had been badly stored, and the emulsion stuck to the backing on the adjacent film in the reel, so once every revolution of the big film reel, there were huge (1/3 of the frame) chunks of mottled image. Where the emulsion had been completely removed, and there was no image, I had to reconstruct by hand from adjacent frames. However, when it was just a big stain, I used a heavily modified version of RemoveDirtMC to fix it, and when it worked, the reconstructed frame was near-perfect.

I haven't posted the results of this work, because it is copyrighted, but I did post a very short before/after of some Polavision restoration. This instant movie film from Polaroid had much of the same problem, because the film was developed in the cassette and then stayed there for 40+ years and, because of the residual chemicals, stuck together and, when unwound after all those years, the emulsion would come off, resulting in a black spot on one frame, and a matching blank spot a few frames later. Here is a few "before/after" frames from that work. You'll need to freeze at a random frame to see the results of what RemoveDirt was able to do. I did no manual work at all; it was all done by RemoveDirt.

Before After Polavision

Whatever inpainting algorithms RemoveDirt uses might provide some ideas for how to do better logo removal.

Last edited by johnmeyer; 1st September 2019 at 19:13. Reason: duplicated words; typos
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