Best way to restore slide colors in LrC with reference scans

[Maurizio]

Operating System

1. Windows 10

I started scanning my slide collection many years ago, but at the time I made the mistake of using a low resolution (around 2–3 MP), just enough for viewing on a monitor. Now, 20 years later, I’m rescanning the same slides at the full resolution my Nikon Coolscan can provide (about 20 MP).
Unfortunately, I’ve discovered that after all this time, the colors of the slides have shifted. As a result, my new scans look quite different from the ones I made back in 2004.
Using the Develop module in Lightroom Classic, I can restore the colors fairly well by using my old scans as a reference. However, there’s no one-size-fits-all solution. It requires a lot of manual adjustments, even within the same roll, depending on the original shooting conditions.
I’ve found the Point Color tool to be quite effective, but it still involves a lot of fine-tuning. One major limitation is that I can’t use the color picker directly on the reference image, which would make things much easier.
My question: Is there a better approach in Lightroom Classic, ideally one that lets me use the old scan as a reference or input target for an automatic process? I know Photoshop offers a Color Match feature, but I’d prefer to do everything in Lightroom without having to add new TIFF files from external editors.

 

[Paul_DS256]

Unfortunately, I’ve discovered that after all this time, the colors of the slides have shifted. As a result, my new scans look quite different from the ones I made back in 2004.

One question I have is what did you differently in 2004 as compared today in colour management/space? Is Coolscan making any changes to colour/colour space?

 

[Paul_DS256]

Which version of Lightroom Classic are you using?

My question: Is there a better approach in Lightroom Classic, ideally one that lets me use the old scan as a reference or input target for an automatic process?

What have you tried besides the colour picker:

• Have you tried the white balance selector on a region to try and get the temperature/tint better?
• Have you tried the new Adaptive Colour profile? If this provides better results, that can be automated.

As I said in my earlier post, what changed in your processing between 2004 and today.

 

[Conrad Chavez]

I don't think this has anything to do with making sure the same edits were applied as before. The original question is how to deal with colors when the processing has not changed, but the condition of the original film has changed. When the original film dyes shift from age, you can't reproduce the same results by applying the same settings as before.

Unfortunately, I’ve discovered that after all this time, the colors of the slides have shifted. As a result, my new scans look quite different from the ones I made back in 2004.
My question: Is there a better approach in Lightroom Classic, ideally one that lets me use the old scan as a reference…

You can try to address the root cause of the film color shift. The color shift is caused because the film dyes are fading, and the challenge is that each dye color fades at a different rate. After fading, the proportions of remaining film dye colors are nothing like they were originally. Traditional color correction assumes that if you just find a key color and correct to that, all other colors fall into line and you’re good. But age-related dye fading shifts colors non-uniformly, so traditional color balancing techniques break down. You have to restore the original dye proportions first.

You can potentially save a lot of time if your scanning software has a feature specifically designed to reverse time-based fading of film dyes. This works because the fade rates of the different dye colors are known, more or less. For example, I run my Nikon Coolscan with VueScan software, and it has a feature called Restore Fading. It works pretty well, or at least it gets my old film to a better starting point for corrections. As it says in their Help files:

This option is used to restore the effects of faded film dyes. Slide film often shifts towards red over time, and color negative film towards cyan.

Results do vary due to variations in different film dyes, and how bad the fading is.

To try to cancel out the dye fading in Lightroom Classic, one possible method is to go to the Tone Curve panel and adjust the Red channel, Green channel, and Blue channel point curves.

A tool like White Balance probably won’t help much with film fading because it’s based on digital cameras, so it works along the blue/yellow (Temp) and magenta/green (Tint) axes. But that’s not how the dyes fade. In film, the dyes that recorded red, green, and blue are fading at different rates, so Temp/Tint won’t reverse that properly because they're the wrong axes to adjust. You can end up just distorting the colors further. This is an example of how standard digital color correction often doesn’t work as expected on scans of faded color film.

 

[Maurizio]

Thank you for your helpful suggestions.

@Paul:

1. The scanning conditions were the same in both cases, with the same color management and no editing after scanning (either in 2004 or today). The most recent scans also match what I see on the color-shifted slides when examined on a light box. So, there is a real color shift, it's not a matter of software.
2. Yes, I did try white balancing the picture (that was actually my very first restoration attempt). It improved things quite a lot, but some colors are still noticeably shifted.
3. I can’t use the Adaptive Color profile since it isn’t available for TIFFs. I might try camera scanning instead, which would let me apply this profile to the RAW files.

@Conrad:
Your explanation is very clear and thorough.
I did try Nikon Scan ROC (Restoration of Colors), but the results were still different from what I expected.
So far, I’ve only used VueScan for color negatives, but I’ll give it a try with slides as well and test the Restore Fading feature you suggested.

I also tried Photoshop Color Match, but the results were below my original expectations.
I’m attaching a few low-resolution JPGs showing some of my attempts. The first set is from a roll scanned in 2004, and the second set is from another roll (2005) that is less affected by color shift. The file names should be self-explanatory. The “Low_res” images are the targets I’m trying to match.

 

[Conrad Chavez]

OK, I gave it a try with your sample files. Unfortunately, I couldn’t find a way in Lightroom Classic that was easy or quick enough. With less severe dye fading I can sometimes get away with adjusting RGB curves in Lightroom Classic, but they didn’t help enough here.

In the end I had to resort to the Channel Mixer in Photoshop. The Channel Mixer seems to be a good analog to the way the color values are influenced by the film dyes. In the first demo below, I managed to get close by adjusting the proportions of the Red, Green, and Blue channels.

By the way, I know that the results in the demo below aren’t perfect because I spent a limited amount of time on it. But the Channel Mixer seems to get it rather close more quickly than other features.

For the second image, you can see that I decided to add a Vibrance adjustment layer to adjust Saturation, and also a Curves adjustment layer. This brings up another point: I had hoped I could just drag over the Channel Mixer adjustment layer from the first image, but it wasn’t the same correction for both images. So I had to start over.

I think this might be another example of how Lightroom Classic is very much designed for editing images made with digital camera sensors, not scanned film. Other examples are lack of easy film negative inversion, lack of any quick removal of film-based dust/scratches, and lack of true film grain reduction. It’s just not a market Adobe targets for Lightroom Classic, and that’s why everything about editing scanned film is some kind of workaround. I’ve tried the Calibration panel in the hope that it might shift color values like the Channel Mixer in Photoshop, but it hasn’t helped much. Probably because, again, the Calibration panel seems to handle color values the way a digital camera sensor does and not the way color film does.

On the other hand, Photoshop 1.0 was originally bundled with a scanner 35 years ago, so its roots are in editing analog sources such as film scans and that gave it a good toolset for that.

Now, I am one of the many here who does use Lightroom Classic to correct high quality film scans in bulk, but that’s because Lightroom Classic generally works pretty well for that purpose despite the fact that its feature set isn’t specifically designed to accommodate scanned film workflows. It works anyway…for film that isn’t damaged too much.

I’ll say again at the end here that I don’t expect any of the color correction shortcuts will work well here, such as Adaptive Color, Auto Color, Auto White Balance, etc. because they are all designed to assume that the underlying color is fundamentally OK. But when film dyes have faded unevenly, that’s not true.

 

[Maurizio]

Thank you very much for taking the time to test my files and share such a detailed explanation. It’s been very helpful in understanding the limitations of Lightroom Classic in this context.

Although I’ve been using LrC since version 4, I only started using Photoshop about two years ago (mainly because it came bundled with the annual Adobe subscription). So I’m definitely not a Photoshop expert.
That said, your explanation makes it clear why the Channel Mixer in Photoshop can handle film dye fading more effectively, since it works directly with the RGB proportions. It seems like a stronger starting point than trying to push Lightroom tools beyond what they were designed for.
I’ll definitely give the Channel Mixer approach a try, although I still hope to continue using Lightroom, at least for the first round of basic editing. Probably the best balance between time and quality will be a two-phase workflow:

1. Phase 1 (scanning software + Lightroom): Aim for “good enough” quality for displaying scans on screen and evaluating them.
2. Phase 2 (Photoshop or another external editor): Refine selected images further, especially those intended for printing.

In the past few days I’ve also tested VueScan instead of Nikon Scan, and I found the Restore Fading function to be quite effective on slides with strong color casts, even though the resulting TIFF is only a good starting point for further adjustments in Lightroom (or Photoshop, in selected cases). Also the Restore Colors option was useful in some cases, combined or not with Restore Fading. These features (unlike the Colorize option, which isn’t relevant here) are based on machine learning/AI, so I expect they will improve as new models are released (BTW: I appreciate that VueScan can save a RAW scan, which provides the option to reprocess scans later from the RAW data without having to rescan the slide).

I’m attaching two examples that combine VueScan restoration features with global editing in Lightroom.
In both examples, from left to right, the several steps of the workflow:
1) Reference image (target for the restoration procedure)
2) Image scanned in Vuescan, with no filters applied (NikonScan would produce the ~same results). Some color cast is quite evident.
3) Image scanned in Vuescan, with flters applied (Restore Color for example1, Restore Fading _ Restore Color for example 2)
4) Image edited in Lightroom, as follows:
Example 1: WB + exposure (-0.4) + one Point Color Shift (to adjust the sky color)
Example 2: Point Color (4 different points shifts) + Highlight correction (-9) + Shadow correction (+65) + Clarity (+9) + Dehaze (+16)

Thanks again for your effort and clarifications!

 

[Conrad Chavez]

Glad to hear it helped! It sounds like you’re on the right track now. After VueScan added Restore Fading somewhat recently, yes that means a lot fewer trips to the Photoshop Channel Mixer for me.

Probably the best balance between time and quality will be a two-phase workflow:

1. Phase 1 (scanning software + Lightroom): Aim for “good enough” quality for displaying scans on screen and evaluating them.
2. Phase 2 (Photoshop or another external editor): Refine selected images further, especially those intended for printing.

Yes, that’s basically what I do. I use the scanning software the same way I use my digital camera: I’m not aiming to get it perfect right away, I’m aiming to collect source image data at the highest possible quality for an easier edit in Lightroom Classic. In the scanning software (for many years I’ve used been VueScan), my two goals are:

• If the scanning software can fix anything about the film that Lightroom Classic or Photoshop can’t, I have it do that, such as infrared-based defect removal, multi-sampling, or fade restoration. I don’t have the scanning software apply anything that I think Lightroom Classic could do better, such as sharpening or white balance.
• Set up the scanning software to save a wide gamut, high bit depth (16 bits/channel), uncorrected RGB TIFF scan. This includes setting the white point and black point a little wide so that they aren’t clipped, and I like to set Color Balance to Neutral. These give the Lightroom Classic color features an objective starting point for its adaptive features, and more editing flexibility.

in Lightroom Classic I batch-apply a Develop preset that has initial settings that work with how I have VueScan set up. For example a default Curve, and I like to apply a small amount of Color Noise Reduction because that makes film grain less visible without over-smoothing.

I know a lot of Windows users still use NikonScan, but we CoolScan users on the Mac had to move on around 20 years ago when Apple changed macOS enough that NikonScan would no longer run. Although NikonScan is obviously the “official” CoolScan software, because NikonScan hasn’t gotten an update in 21 years even for Windows, VueScan takes advantage of more modern techniques for the same features. And the software seems to have been re-invigorated by the involvement of developer Ed Hamrick’s son David.

(BTW: I appreciate that VueScan can save a RAW scan, which provides the option to reprocess scans later from the RAW data without having to rescan the slide).

VueScan raw is a great feature that isn’t commonly found in other scanning software. You probably know this, but because I see VueScan raw misunderstood often, for everyone else it’s important to note that VueScan raw is not the same as digital camera raw.

Digital camera raw is straight sensor data that hasn't yet been demosaiced into standard RGB channels. VueScan raw can’t be the same as camera raw because the output of a film/print scan is always already converted to channels. What raw means here is that the only things VueScan altered are the ones you can’t change after the scan, which are the settings in the Input and Output tabs. But a VueScan raw won’t include the settings in the Filter and Color tabs (maybe Crop but I’m not sure).

A good analogy for VueScan raw is when professional videographers do “log (logarithmic) capture.” What they record isn’t in a literal camera raw format, but the initial look is intentionally flat and unsaturated with a low gamma value, and no in-camera tone/color corrections or looks. The point of both that and VueScan raw is, again, to capture source data in a way that preserves the most dynamic range and flexibility for later corrections, without actually being camera raw data. I only thought of that analogy when I noticed in the VueScan help file that if VueScan is set to save as both raw and 16 bits per sample, it sets Gamma to 1.0, which reminded me of what they do in video for log capture.

 

[Maurizio]

Thank you again, Conrad, for your follow-up reply!

After spending a few more days scanning slides, I can definitely confirm how useful VueScan’s "Restore Fading" function is. In many cases where I didn’t have a low-resolution reference scan (because it was the first time that a slide had ever been scanned), "Restore Fading" effectively removed the blue color cast caused by aging. The restored colors still retain a bit of a “vintage” look, so some additional editing in LrC is still needed afterward.

Just a few more observations:
(a) I noticed that the TIFFs produced by VueScan tend to be slightly overexposed in the highlights, so after several tests I set the White Point to 0.2 in VueScan to compensate.
(b) In addition to color shifting, many of my older slides also show noticeable darkening in the shadow areas. These details can usually be recovered in Lightroom Classic by lifting the shadows. Here, the two-pass scan option in VueScan helps a lot, as it reduces noise in the shadow regions by adding more meaningful bits to the TIFF file (at the cost of a longer scanning time).

Since yesterday, I’ve also been experimenting with color.io, a very interesting tool that can, among other things, export custom LUTs usable as Lightroom profiles. If this proves effective, it could be a big improvement over a standard Lightroom preset and perhaps a great way to avoid additional editing sessions in external editors.

 

[Conrad Chavez]

Hi Maurizio, thanks for adding more information. I agree that the default VueScan clipping points are a little tight, and I move them out too. My White Point setting is 0.01%. I think the VueScan defaults are intended to produce a pleasing result for those who want a “snappier” image right out of the scanner, but of course the default value may clip too much for those who want to do most of the correction in another application such as Lightroom Classic.

I have not used the multi-pass option very much, but yes, it’s a good thing to do for more valuable images where preserving quality is worth the additional scanning time. color.io sounds interesting too. If your goal is to customize LUT-based color corrections that can be turned into a preset, have you also tried exporting Photoshop adjustments as a LUT from a sample scan, and then converting that to a Develop profile for Lightroom Classic/Camera Raw to apply to other scans?

 

[Maurizio]

If your goal is to customize LUT-based color corrections that can be turned into a preset, have you also tried exporting Photoshop adjustments as a LUT from a sample scan, and then converting that to a Develop profile for Lightroom Classic/Camera Raw to apply to other scans?

That sounds very, very interesting! As I said, I’m not very experienced with Photoshop, but I’ll take a look and give it a try. Thanks!

 

[PhilBurton]

As an option, you could consider the new color correction features in Negative Lab Pro

https://forums.negativelabpro.com/t...mproved-batch-editing-and-more/8492/20?page=3

 

[Maurizio]

Oh, great tip, thanks, Phil!
I’ve already used NLP, but only for camera-scanned b&w negatives, so I’m not very familiar with the various color adjustment options it offers.

I just did some quick tests today, with TIFFs produced by VueScan (with no filters applied), and the results look quite promising using the default NLP settings (Type = Positive, Source = TIFF Scans).
However, some additional editing seems still required.