Estimating the original colors of the original Star Wars trilogy — Page 5

yotsuya said:

Okay… I must have this. I have a stack of about 200 photos my mother-in-law brought that my wife wants me to scan. most aren’t too bad, but some are almost pink.

So, it seems I might not be completely crazy for putting my trust in the GOUT as my guide for my color correction. I would very much like to see the full movie done with your color correction algorithm.

It seems you were right after all. It appears the colors of the GOUT are close to the LPP, but with less contrast and saturation.

DrDre said:

The distribution of the concentration of dyes is logarithmically related to the color intensity distributions of red, green, and blue.

DrDre said:

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

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

Thanks for sharing! So RGB is needed because it is the color space of the light filtered through the CMY film, or because the scanner is sensing in RGB? or both?

Is there a chance you would test your newest methods on some faded footage and not just single images if it’s possible?

dahmage said:

DrDre said:

The distribution of the concentration of dyes is logarithmically related to the color intensity distributions of red, green, and blue.

DrDre said:

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

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

Thanks for sharing! So RGB is needed because it is the color space of the light filtered through the CMY film, or because the scanner is sensing in RGB? or both?

Yes, the concentration of dye is proportional to the logarithm of the amount of filtered red/green/blue light.

pittrek said:

Is there a chance you would test your newest methods on some faded footage and not just single images if it’s possible?

I will soon post a video sample for reel 1.

two things doc…

1. This is worthy of a Nobel Prize. Not joking, millions could benefit from this technology.

2. I think you would end up removing any intentional color timing from the film. Think about it. Take a photo, adjust the colors without clipping any of them too badly. Take the original photo and do it again. Do it in whatever color space you want. Now hit the button on each of the differently timed photos. They all get back to being pretty neutral, right? I’m not complaining, as this is an amazing tool in color recovery, but I don’t think you can say these were the colors on opening day.

-G

g-force said:

two things doc…

1. This is worthy of a Nobel Prize. Not joking, millions could benefit from this technology.

2. I think you would end up removing any intentional color timing from the film. Think about it. Take a photo, adjust the colors without clipping any of them too badly. Take the original photo and do it again. Do it in whatever color space you want. Now hit the button on each of the differently timed photos. They all get back to being pretty neutral, right? I’m not complaining, as this is an amazing tool in color recovery, but I don’t think you can say these were the colors on opening day.

-G

I agree you would, if you would correct shots individually. However, the idea with correcting a film reel, is that you calibrate the model on shots you know to have a neutral color (or no delibirate color cast), like the majority of the Tantive IV scenes. If you include enough shots, the average distributions of the red, green, and blue channels should converge for an unfaded print, allowing you to accurately estimate the color shifts for each color channel, and for each color intensity. You then apply this correction to the entire reel, which is what I did in the examples I showed for Star Wars. All the color relations between shots remain intact, since you apply a uniform correction across scenes. Unless the shots you chose originally had an intentional color cast or an unintentional color imbalance (and even in then it would have to be an imbalance that persists across scenes or an entire reel), the final result should be an accurate representation of the original color timing.

One of the challenges involved with correcting an entire reel with one model, is that color fading may vary a bit across scenes. For example the Vader/commander shot still has a slight teal cast:

The question then is, whether the shot originally had a slight color imbalance, or whether the shot was slightly more faded than other shots. However, to make it more appealing, you can apply a second conservative correction with the algorithm for the specific shot or sequence of shots (keeping in mind the points raised by g-force, and the assumptions underlying the algorithm):

If I well understand, neutral color means equality between red, green and blue in the shot. So, how do you know that the majority of the Tantive IV scenes have neutral color ?

If there’s a little green in the walls, red lights, blue shirts etc., what allow us to suppose the balance is perfectly grey ?

UnitéD2 said:

If I well understand, neutral color means equality between red, green and blue in the shot. So, how do you know that the majority of the Tantive IV scenes have neutral color ?

If there’s a little green in the walls, red lights, blue shirts etc., what allow us to suppose the balance is perfectly grey ?

Neutral color for a single frame has many definitions, but in general it means no delibirate color cast, not necessarily equality between color channels at each intensity. For single frames you have to set the strength of the amount of color balancing, to allow for the fact that colors for single frames do not have to be perfectly balanced at each intensity. If there are few colors in a frame, the quality of the result will be highly dependent on the color balancing strength you use, and the frame you’re attempting to correct. However, if there are enough different colors in a frame, the result will generally be very good, and far less sensitive to an increase of the color balancing strength, once a color cast has been removed. However, the method remains most suitable for color correcting multiple frames simultaneously, where the assumption that colors average to gray is generally an accurate approximation.

I’m preparing a video sample, but while we wait, here are three more corrected frames for reel 1:

DrDre said:

I’m preparing a video sample, but while we wait, here are three more before and after examples for reel 1.

I really like these! especially the last one, with the red light behind leia

edit: I like it because it wasn’t subjective in its correction.

Here are a few more examples:

Double post

This is also an interesting comparison.

Star Wars Legacy Edition (preliminary):

Automated color correction:

Just to show how great these colors are with adjusted levels to counteract some of the darkness inherent in the print:

Original correction:

Luminance adjustment:

Original:

Adjusted Luminance:

I would be interested in seeing what your color matching tool does matching the blu-ray to these 35mm adjustments.

Darth Lucas said:

I would be interested in seeing what your color matching tool does matching the blu-ray to these 35mm adjustments.

Me too, so that’s definitely on the agenda.

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