Stabilise your film scan

[williarob]

As promised, here is a quick tutorial demonstrating what I believe is the best way to stabilize your film scan when using PF Clean:



As mentioned briefly in the video, there are other ways to stabilize shots in PF Clean, but I found this to be the most effective when using sprocket holes as your reference point, and it's probably the least well known way to do it.

Sorry about the audio - the headset I was using has very creaky plastic which can be heard throughout the recording.

[williarob]

Found a way to improve the perf tracking in After Effects:



Now that I'm working with a lot of .dng raw files, I have been experimenting with ways to improve the tracking in After Effects, because that saves me from having to export as dpx or tiff, do the tracking in pfclean and re-export back to After Effects.

The biggest problem when tracking in AE is that it regularly loses the track, and even if you have it set to stop tracking when confidence is below 80%, sometimes it will slip into the middle of the perf, and then track right to the end of the clip with 100% confidence that the now all white square is tracking perfectly, forcing me to trace it back to where it got lost and restart it from there... Basically, you just have to supervise it all the time and constantly put it back on track, which is a pain when you are trying to stabilize an entire reel (which with 16mm film is often 40 minutes long or around 60,000 frames.)

So anyway, I was experimenting with levels, and grayscale, and contrast, etc hoping to improve the track and I think I have come up with a combination of effects that greatly improve the chances of a good track.

1. Import your clip into a new composition.
   
2. Right click on the layer and choose "pre compose..." In the dialog that appears, it shouldn't matter which option you choose because there are currently no effects or edits applied.
   
3. Open your precomp and apply the following effects:
   
   which will convert this:
   
   into this:
   
   and really make those sprocket holes stand out (and therefore much easier to track)
   
4. Switch back to your main composition (which should now look the same)
   
5. Open the tracking window (Window -> Tracker)
   
6. Click on the layer containing the precomp, and then in the Tracker panel click on Stabilize Motion
   
7. You will probably have to increase the zoom to 100% to see the tiny square that represents your new track point, sitting in the center of the window. It should be a square within a square. The outer square represents the search area, the inner square represents the part of the image you are hoping to track. Without touching the + sign in the center, click and drag the track point over to the perf you want to track.
   
8. Resize both the inner and outer squares to suit your needs, but keep in mind that the smaller the track point and the smaller the search area, the faster the track can work. Usually it works well if you track one of the corners:
   
   Watch a few seconds of your scan, or scrub the time line back and forth to get an idea for how much your perfs move. The film on my scanner sits in a track that prevents it moving side to side much, but the sensor that tracks the sprocket holes is some distance from the gate, so the film moves up and down in the frame quite a lot. My search area therefore typically looks like this:
   
   
9. In the tracker panel, uncheck Rotation and Scale, so that you are only tracking Position. Then click on Options.
   
10. Turn off subpixel positioning and set it to "Stop Tracking" if confidence is below 80%.
    
    
11. Click OK to close the options dialog and then click on the play button in the tracker window.
    
12. Watch for a while to make sure your track is good and then go do something else, because it could take hours. Be aware that if your monitor goes to sleep or you try to do anything else in AE, tracking will stop, so it's a good idea to set your monitor to sleep after 2 hours or so. You should still check on it regularly though, it may still lose the track and it's very annoying to come back after an hour and find out it stopped just minutes after you walked away! Tracking tends to get slower and slower the longer it tracks, and if you let it go too long sometimes you won't be able to stop it because system resources drop so low the application just won't respond. So it's also a good idea to stop it every 30 minutes or so even if it's still tracking well. After it stops, click Save to save your tracking info (in case it crashes) and then continue tracking. Going to Edit -> Purge Memory and Disk Cache before restarting the track can also help speed it up for a while.
    

What to do if it loses the track



- If it loses the track, it should stop on it's own, but if it doesn't just click the stop button in the tracker panel. Then click on the layer in the timeline and press U on your keyboard to reveal the keyframes.
- Move to the last keyframe and then keep pressing ctrl + <- (Left Arrow) until you see the track point is back on track.
- Using the mouse, draw a square around the keyframes you need to delete. They should turn blue:

- hit the delete key on your keyboard to delete them.
- Move to the first frame that doesn't yet have any keyframes (presumably the one(s) you just deleted) and manually move the tracking square back into position.
- click the play button in the tracking panel to resume tracking.
- rinse and repeat as necessary.
- If it continues to lose the track regularly, try changing the size and/or shape of the tracker and search area. Including more (or less) will usually do the trick.

What to do when it's done

- Click the apply button in the Tracker panel
- You can choose to Apply just the X (horizontal) movements, just the Y (vertical) movements, or both X & Y. If your scan only moves up and down, you can just apply the Y.
- Finally, go back to the precomp and remove or disable the effects applied to make the perfs easier to track.

Edit: It may also help to add the Hue/Saturation Effect and reduce saturation to 0.

[deleted user]

Great idea! I've experimented with similar techniques for the AutoOverlay AVISynth plugin, but I never really got it to work really reliably.

[williarob]

Figured out how to get Phoenix to stabilize a film scan using the sprocket holes this weekend. Phoenix 2018 & Up has DVO Steady and DVO Steady 2, which is a newer version. So far I have only experimented with v2. The documentation describes several modes, but is pretty vague on how to set it up for the best effect.



I spent hours this weekend trying different settings on both 35mm and 16mm film scans and eventually found success with these settings:





For 16mm, I set the ROI (Region of Interest) to include just the bottom perf and the area above and below it. To set the ROI you can either type in the numbers or drag and drop the white box to size, shape and position it. I found a combination of drag and drop with some fine tuning by typing was easiest. In my example above, the bounding box doesn't appear to be perfectly vertical, but that's because my camera isn't completely vertical either, so I had to rotate the image slightly.

"Border weighted" with this selection worked much better than Film Frame or Film corners, which I also tried with the full image selected and with just the frame part.

My 16mm scans jump up and down quite a lot, so I have increased the "Y" values from the defaults to help offset this.

For 35mm, I tried selecting a single perf and all four perfs on one side. In the end I decided the latter worked slightly better, but your mileage may vary.

[Dr. Cooper]

One thing I also found out in Resolve: It usually works better when you're using the whole perforation instead of just one corner:



I tried it with a VS-print which was drifting around heavily (and I mean really bad) and while the trackers were thrown off early when just using one corner it worked for entire reels at once with both corners selected at once. I only had to re-adjust single frames where the perforation was broken.

Maybe this also helps in After Effects or PFClean!

[althor1138]

This is a macro that I've created in FIJI (Imagej). It can be used for sprocket stabilization or image stabilization.

If you are interested in trying it out just download the fiji.app folder and place it in the root of your C drive and run the executable. You probably need Java installed.

It's probably a good idea to check out the demo video to see how it works.

https://drive.google.com/drive/folders/1...sp=sharing