Digital Zoom / Resolution Question

[markburgle]

Hi everyone, first time post. I'm making a music video on an absolute shoestring. I have some footage that I shot on a cameraphone which had a big black spot on the lens which I couldn't clean or remove, so I digital zoomed to crop it out.

I'm now trying to figure out how usable this footage is. It was shot on "Full HD", 1920x1080, and it seems (correct me if I'm wrong) that the zoom factor (2.8) will have reduced the resolution to roughly 0.2 megapixels.

Thing is, this footage - playing on my 13 inch laptop - looks fine in the rough-cut alongside other footage from less rubbish cameras. When I zoom right in using the inspector in Resolve (my vid editor of choice) it seems to pixellate at around the same zoom factor as other footage.

I don't need this video to look pristine because (if you hadn't guessed) I'm leaning into the DIY aesthetic with it, but I'd hate for some portions of the video to turn to pixellated crap on a larger screen. What do y'all reckon? Can I get away with it? Is there a way I can definitively check how this footage will cope on bigger screens (given that I don't have access to any)? Advice much appreciated, thanks!

[abolibibelot]

A screenshot or two would help in assessing the situation.

[johnmeyer]

If you have a PC you can use the Delogo filter for VirtualDub. Both are free and both require nothing more than a simple download. Here is a tutorial I made years ago to show how to remove a spot from a sensor or lens, without having to crop it out. If the spot is pretty small, the final result can be near-perfect:

https://www.youtube.com/watch?v=Z12TutFSg8c

[markburgle]

A screenshot or two would help in assessing the situation.

Right you are! Here's an exported still - the middle one is shot with the dodgy camera.

[markburgle]

If you have a PC you can use the Delogo filter for VirtualDub. Both are free and both require nothing more than a simple download. Here is a tutorial I made years ago to show how to remove a spot from a sensor or lens, without having to crop it out. If the spot is pretty small, the final result can be near-perfect:

https://www.youtube.com/watch?v=Z12TutFSg8c

Damn, wish I'd known about this before! The spot isn't small to be fair, it's more of a blob that shows up around 5x8mm on my phone screen

[abolibibelot]

So, if I understand correctly, you shot that video in 1920x1080 but in vertical position{*}, then cropped it to about 684x384 to get rid of that “blob”, then inserted it as a third of a horizontal 1920x1080 frame, where it gets resized to 650x1080 (probably after some further cropping since that gives an aspect ratio of 1.66, wider than the original 16:9 which is about 1.78) ; so the actual resizing factor would be closer to 1.6~1.7 if I'm not mistaken. And indeed that's not shocking visually, if anything the shot on the right side (the dude who looks like the Punisher) seems softer, while the one on the left side (the dude who looks like a scandinavian heavy metal bassist) seems crisper but only marginally so. So I would say that it's good to go.


{*} There was a funny video on that subject but it's no longer available... If anyone wants to watch it :
Vertical Video Syndrome - A PSA [Bt9zSfinwFA].mp4
However it should be noted that this is one of the rare cases where shooting vertically was actually wise, to have three (presumably talking) people edited together on the same frame, with the best possible quality (each third of the frame being shot in full 1920x1080 resolution). Or perhaps it was not, depending on where the “blob” was located on the frame -- it may have been possible to avoid any resizing by shooting horizontally with the subject framed out-of-center for him to occupy a blob-free area. But what's done is done. With a DIY approach it's frequent to have to deal with less-than-ideal situations. That's why there are still professionals in that field, even though anyone can theoretically shoot decent looking footage with affordable devices, which would have been unthinkable 10-15 years ago.

[johnmeyer]

I don't want to berate the OP in any way because he is one of billions who do this, and also because he clearly knows what he's doing, but can we all agree that "portrait mode" moving images should not be called "video?" We don't perceive the world around us in portrait mode, and our TVs are all landscape.

These always look like video shot through a keyhole.

I'm bitching because I've had to do the same thing as the OP -- with video given to me by other people -- namely, crop the heck out of it and end up with something far less than the SD video we all thought we'd left behind.

[markburgle]

So, if I understand correctly, you shot that video in 1920x1080 but in vertical position{*}, then cropped it to about 684x384 to get rid of that “blob”, then inserted it as a third of a horizontal 1920x1080 frame, where it gets resized to 650x1080...

Yep, you got it

However it should be noted that this is one of the rare cases where shooting vertically was actually wise...

Tell it! Yeah the above split-screen was the goal there so it made sense. I'm going to try and get to a bigger screen just to be sure I think, but thanks for your input guys.

Just because, here is the blob. Beware of the blob...

[johnmeyer]

Have you tried using Delogo, as I suggested, and as I showed in my tutorial? Put the red dot around your fuzzy dot, use the fourth option in VirtualDub Delogo to load that image, and then save to a new video file. I've attached an image which shows what the mask should look like.

Your dot is much larger than the sensor dot I showed in my tutorial but you have a static (slow-moving) image, so I suspect the result will still look pretty darned good. I don't think there is any other method that is likely to look better.

[markburgle]

Have you tried using Delogo, as I suggested, and as I showed in my tutorial? Put the red dot around your fuzzy dot, use the fourth option in VirtualDub Delogo to load that image, and then save to a new video file. I've attached an image which shows what the mask should look like.

Your dot is much larger than the sensor dot I showed in my tutorial but you have a static (slow-moving) image, so I suspect the result will still look pretty darned good. I don't think there is any other method that is likely to look better.

Thanks John but I've already shot the footage pre-cropped with digital zoom. If I were to go to the trouble of reshooting I would rather make sure to get hold of a better camera!