DrDre

pittrek said:

Hm… I have a private 8mm film which is horribly red faded. I have tried various color correcting methods in the last 10 years but none of them worked as good as I hoped. Will you go public with the newest version of your tool?

That is the plan. I’m using the Star Wars LPP as a kind of test case, to discover the method’s strengths and weaknesses. The difficulty is coming up with a work flow that can be intuitively incorporated in a software tool. So, although it may take a little while, it will definitely be part of v3.0.

FrankT said:

So presumably the colours are identifiable from particles trapped in the interpositive?

It’s all happening in the digital realm. It uses a model to describe the interactions between the various colors, and to model the chemical changes in the dyes on the photo or print.

Another example of a faded photoghraph I found on google restored with a mouse click.

Before:

After:

Considering these results, I believe that the restored colors on the Star Wars LPP are probably very close to the original colors, and reinforce the idea that Star Wars during it’s theatrical run in 1977 looked a bit different from what Technicolor prints would have us believe.

For all of you interested in some theory on digital film correction, here’s a reference paper:

http://restorationfilms.free.fr/telechargements/CGIP2000.pdf

The color correction model in the above paper presupposes a set of desired colors. The color correction algorithm I developed in principle also works on single frames, under certain conditions, but does not use a set of desired colors like in the paper. So, here’s what my algo does for the example in the paper (low resolution):

Before:

After:

The algorithm naturally can also be used to correct faded photographs. I came across this website of a guy who specializes in restoring faded photos:

http://cyleow.blogspot.nl/2012/12/restore-and-recolor-my-world.html

As he states, it can take hours to manually correct a single photo or frame. This is what the algo does in a matter of seconds for two of his examples.

Before:

After:

Before:

After:

The basic theory is pretty simple. Color fading happens as the dyes in the print degrade, which happens at different rates for the three different dyes (cyan, magenta, and yellow). The color distributions shift to brighter intensities. The distribution of the concentration of dyes is logarithmically related to the color intensity distributions of red, green, and blue. Over a large enough number of pixels/frames the average color is gray, which follows from the central limit theorem, and voila, you’ve got an algorithm.

Wazzles said:

It’s not a useful indication of how the film actually looked though. It’s not about what’s “most natural” if it wasn’t “natural” to begin with.

I agree. This thread is mostly about finding ways to rewind time, and bring the print colors back to it’s original state, warts and all. These do not necessarily have to be the most appealing colors.

Darth Lucas said:

Looks pretty good. All the shots on the tantive look a bit too dark/saturated to my eye, but the colors themselves look good 😃

If I remember correctly the LPP is a dupe of another print. The contrast of a print increases with each generation (something about optical gamma), similar to a 16 mm print, which is also generally a copy of a 35 mm print, so the scan should be gamma corrected for a better viewing experience, but it’s likely the original print was pretty contrasty.

A few things have happened over the last couple of days. Firstly, Williarob was kind enough to allow me early access to the Silverscreen Edition Grindhouse, to conduct some further color experiments. Secondly, I updated the color correction algorithm. After catching up on the in and outs of film, and digital film corrections, I realized I was working under the wrong assumptions, namely that I should work in the YCM color space, when in fact it should be RGB. I could go into the theory of it all, but it suffices to say, that everything fell into place, and I was able to correct reel 1 of the Star Wars LPP with a single color correction model without green shifts or any other major anomalies. I also ran some first tests on reel 2. Here’s a gallery of frames from reel 1, before and after, and one frame from reel 2. Surprisingly the colors are in many ways closer to the GOUT, than the Technicolor prints. No manual adjustments were made to these corrections. These are simply the result of a scientific theory for color fading.

Reel 1:

Reel 2:

Here’s a regrade for the R2-D2 in the canyon scene.

Bluray:

Bluray regraded:

Here’s a regrade of the soldier shot based on the Spanish LPP.

Bluray:

Bluray regraded:

Here’s another test regrade of the explosion aboard the Tantive IV.

Bluray:

Bluray regraded:

Note the mint colored Tantive IV walls.

Yes, I used one of the early uncorrected samples…

LPP stands for Lowfade Positive Print stock. It was introduced by Kodak in 1982.

I like those as well, but those were created using different references for different scenes, which makes it difficult to obtain consistency between shots, both in terms of color and luminosity. In addition, the color of the Tantive IV walls tended to be pretty neutral in the earlier regrades, while Mike Verta and others have maintained they should have a hint of green in them. Since, I will assist Williarob on color correcting piota’s scan of the LPP, these corrections are also a precursor to how the LPP might look, once we’re finished color correcting it. At least I would like the colors of the bluray regrade to be consistent with the corrected LPP. I suspect Despecialized v3.0 will still be mostly inspired by the Technicolor prints, so it will be nice to have this alternative color grading based on a best guess of the colors of a 1977 LPP.

I personally feel the color corrected LPP reference has produced the best results so far, so I think after a few more tests, I will use it as my main reference. Here’s the latest set of LPP based regrades:

…and here’s the Vader strangling shot.

Bluray:

Bluray regraded:

Here’s my color grading for the C3-PO shot, based on the automated correction of the Spanish LPP.

Bluray:

Bluray regraded:

I decided to adjust the Tatooine shots a little bit further:

yotsuya said:
These look outstanding. The others still look too green.

The others are rough corrections, that were done by an automated algorithm. These are the final color gradings based on the rough corrections. The others will get the same treatment.

You’re welcome! Version 3.0 should be out in a while, and will contain the automated faded print correction algorithm. Piota’s scan of the Spanish LPP of Star Wars should provide a good basis for testing the merits of this methodology for correcting an entire print, but the results have been very promising so far…

I think I will do a few more tests based on the automated regrade of the LPP. I believe the colors are pretty reliable, and generally require less adjustments than with the previous references I used. They also represent an alternative to the Technicolor print that are often used as a reference for what Star Wars looked like in theatres back in 1977. It will also ensure the color grading is self-consistent.

Some of the shots I will be testing:

I think I really like those last regrades…

Maybe to a certain extend, but this method is specifically meant for faded prints, which tend to fade in a predictable manner for each reel, depending on the way it was stored. LOTR was digitally manipulated, and generally the person doing the manipulation does not do it in a predictable manner.

Here’s a set of adjusted regrades, based on the automated color correction of the Spanish LPP:

It isn’t. Each movie is corrected without prior information or other references. All the information you need is in the movie itself. All you need to do is select a set of appropriate calibration frames from the print reel you want to correct, and the algorithm will estimate the correct colors. TESB and ROTJ are corrected independently.