Optimize NLP for RGB light sources?

[nate]

Real Life Examples - Negative Lab Pro v2.3 + iPad as Backlight

Just to show some real life examples… all of the below were digitized using a Fuji X-T2 with an iPad as the light source. They were converted using Negative Lab Pro v2.3 (currently in beta testing), and adjusted to taste, with the final settings shown.

Version 2.3 uses a new camera profile that simply works better across the board (for both white light and for RGB light). So I’ll be interested to see if you are able to get better results with your breadboard light source in v2.3 than you did previously.

Examples of Negative Lab Pro v2.3 with an iPad light source:

To my eyes, at least, the colors in these is quite good - on par or better than the same negatives in the Kaiser light table. Good skin tones, good sky hue, good distinctions between yellows and greens, etc…

And of course, there is a LOT of adjustability within them.

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But why am I getting bad colors with my RGB light table?

First, there are some major improvements in v2.3, so I’ll be interested to see if you get better results with that… but in general, there are a few reasons that colors can get wacky:

1. The importance of color balance. Just as you would in a darkroom setting, a lot of the color balance will come down to the operator. Almost all images will need some tweaking of the “temp/tint” settings.
2. The unpredictability of deteriorated film. The older your film negatives are, the more damaged the colors in them will be. This is especially true if they have not been stored properly. This is true regardless of if you are using a white lightsource or an RGB lightrsource. Will using a perfectly calibrated RGB lightsource help? Perhaps it will improve the starting point. But even then, you will need to make serious adjustments to get correct colors out of final.
3. The default settings in Negative Lab Pro. The defaults in Negative Lab Pro are not set in stone. The default setting, for instance, is to use the “LAB - Standard” tone profile, which adds a fair amount of contrast, which increases perceived saturation and make it appear more like a lab scan. If you wanted to begin in a more “neutral” starting point, you could use something like the “Linear - Flat” tone profile, and save that as your default setting.
4. The variability of the scene itself - Most film conversion software (including Negative Lab Pro) works by analyzing the scene of the negative itself. This works well in most cases, but can fail in certain types of scenes, especially scenes with either one dominant color, or very low dynamic range. I’m working to improve this by doing more contextual analysis within a roll, but this is an important consideration in why some scenes may not have as good of an initial conversion as other.
5. Issues with Setup - since camera scanning is a DIY adventure, there are a lot of potential mistakes that can be made along the way. Many many issues I see with color reproduction come down to various errors in the setup that cause uneven light, lens flare, or sensor flare. Most users who experience color issues will benefit from a good examination of every part of their setup. Often it is a simple as masking out light, or upgrading to a new macro lens with better coating.

In my humble opinion, each of the above 5 variables will play a larger roll in the final colors of your image than the difference between a High CRI White Lightsource and an RGB Lightsource.

I say this having converted tens of thousands of negatives from various cameras and light sources, and having spent the last 5 years or so working almost exclusively on this project.

But again, I’m not at all opposed to finding ways to improve calibrations for various light sources, and I do believe that good RGB light sources would be a wonderful tool to have. I would just caution against thinking that it would be any kind of silver bullet. Any combination of camera, light-source, software, etc. will need adjustments to get the results the user wants.

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@davidS

I think that work with breadboards can supply that confidence. I have built a breadboard light source using commercial LEDs that matches the spectral distribution of the Fuji Frontier light source. But I don’t know of software to use that will work well with it.

It would be helpful to have samples to test in Negative Lab Pro to see for myself what is happening and if it could benefit from adjustments to the profile. If you’re up for it, you can email them to me at nate@natephotographic.com

@davidS

Obviously there is much here that I don’t understand. Can someone recommend a reference that I should read?

The Adobe DNG Specification is a good place to start to understand what is happening inside a camera profile (at least in Lightroom).

And here is a really good multi-part series on understanding how color works in digital cameras…

@davidS

Is it enough to just turn off the camera input profile in NLP?

No, that’s not how it works. There always needs to be a camera profile when working with RAW. Otherwise, there would be no instructions on how to turn the RAW sensor data into white-balanced sRGB data.

@davidS

Our digital workflow includes so many more levers. But shouldn’t our default be as simple as RA-4? Beyond that, pull the digital levers for creative adventures.

I could perhaps introduce a “mode” where you only see adjustment tools in Negative Lab Pro that were possible in RA-4. Or, you could try the following:

1. Set the tone profile to “Linear-Flat”
2. Only adjust the “Brightness” and “Temp/Tint” sliders in Negative Lab Pro.

But many people use Negative Lab Pro for different reasons and expecting different outputs, so I try to make it as flexible as possible to work with many different setups and desired results.

Again, thank you for this discussion!

I’m always looking to improve Negative Lab Pro and make is a great experience for all!