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Post #1096441

Author
lansing
Parent topic
Color matching and prediction: color correction tool v1.3 released!
Link to post in topic
https://originaltrilogy.com/post/id/1096441/action/topic#1096441
Date created
10-Aug-2017, 9:42 AM

DrDre said:

lansing said:

Williarob said:

alexp120 said:

alexp120 said:
If you look at williarob’s “Restoring Color to Red Faded Film” video

http://thestarwarstrilogy.com/starwars/post/2016/09/12/Restoring-Color-to-a-Faded-Eastman-Print-of-Star-Wars

…beginning at the 15:47 mark, he explains how you can build a model containing a wide variety of colors. You are grabbing sample frames of the shot that you are working on from both the reference video and the test video, and creating LUT’s of all the colors in that shot.

I noticed that the number of sample frames of the shot from both the reference video and the test video is 16. Why 16?

I think it had to do with how big the montage image was going to be. I didn’t want any blank areas, so it had to be 4x4 or 3x3 or 5x5, but if I recall correctly, any bigger than 4x4 at that resolution (each frame about 848x360? - something like that) would just leave the color match tool hanging indefinitely on my system. Your system may be more or less powerful than mine, so your mileage may vary.

If you were using the tool to grade a film like Raiders or Star Wars then I would recommend you take 8 to 16 frames from every scene (rather than shot) and turn them into montages, one of the source (or test) frames and one of the target (reference) frames and create a LUT for each scene.

In my testing, I did try grabbing up to 64 small frames (smaller than SD) from an entire reel of Star Wars and generating montages and a single LUT for an entire reel, but found it was much less accurate than doing it on a scene by scene basis. However, this was probably because the reel did not have consistent colors (parts of the reel were scanned with different color settings) so 1 LUT to rule them all was not possible until all the shots had been color balanced first.

However you may be able to create a single montage for an entire episode of what you are working on, especially if the color changes are consistent.

This is a very late follow up because I was slacking off. I created a montage reference image and it sure is more accurate. My question now is is 4x4 montage the overall best size as a reference for a scene? Or is it better to build the montage with 1 frame from each second in the scene?

My second question is what is the minimum resolution we can use to create the montage without affecting quality when building the color matching model in the program? It sounds too crazy to build the montage with the full size 1920x1080 frames.

Montages will work, but the more frames the more difficult it is to match the frames, with a higher probability of artifacts. For the fast mode the frame size is significantly reduced.

For making a montage, what is a good size for any individual frame to reduce to? Because it makes sense to reduce a 4x4 montage of 1920x1080 frames, but it doesn’t make sense to reduce the size of a 4x4 montage that is 1920x1080, since each frame inside the montage is very small already.