Correct ADX10 handling for ACES 2065-1 DSLR scan of film negative

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I’m interested in experimenting with Kodak Vision stock (50D, 500T etc) for still photography printed as ECN-2 and then ingesting the negatives into ACES using a DSLR with an IDT based on spectral sensitivity data for that sensor. This is just for a personal creative project and I’ll be using Nuke for all my color transforms.

Assuming a good accuracy with the camera sensor and that IDT, my starting point is a negative scan in the form of an ACES 2065-1 linear EXR. I assume I would then want to transform it using the ADX10 IDT, but I’ve been doing more of a generalized Cineon type of approach in my early tests.

As far as inverting the negative with the aim of placing the base emulsion as RGB Dmin 95 CV, from my initial tests with regular photographic film negatives I’ve had decent results in Nuke by either:

  1. Dividing out the base emulsion color from the raw negative scan and then inverting, followed by log to lin.

  2. Subtracting the base emulsion color sandwiched in between a lin to log round trip.

However since I’m not currently using the ADX10 IDT, I think these approaches are relying on the native logarithmic response of the printing density of the negative. ie, there is no attempt at “unbuilding” the film stock, or conforming to ADX code values - so there’s room for improvement, even if my stated purpose means that there’s a point where it’s “good enough”.

To understand more about ADX, I had a look at TB-2014-005.pdf in the ACES documentation that can be summarized as “essential notes on using APD and ADX”. My question then is, do I need to do a printing density to ADX transform before applying the ADX10 IDT?

And for that printing density transform, do I need to do a single APD to ADX10 transform as per page 14, or since this is not going to be scanned on a film scanner that encodes with ADX code values do I first need to do a Status M to APD Conversion as per Annex C in that document, followed by the APD to ADX10 transform?

Bonus points: within this home-brew DSLR negative scanning community, I’ve read about some people using individual red, green and blue LED lights along certain wavelengths to further split up the negative scan to get a better result than a high CRI white light and then I would recombine them in Nuke.

For example, the hardware portion of this article:

Any comments on this? It obviously would be closer to the result of a more high end RGB film scanner.


This looks right up my alley, although sadly I don’t have any concrete advice for you. What are you hoping to achieve by ingesting film negatives into the ACES ecosystem? Pairing film with digital footage? Do you plan on working with the ACES RRT or rely on the film’s response for your “tone mapping”?

Regarding the RGB lights idea, it’s an interesting idea. My experience with saturated lights is that my camera sensor is much more sensitive, and prone to blowing out, certain wavelengths over others, which would imply the lights would need to be at different intensities to perform at their individual ideal exposures. Also, it’s likely that any RGB combo will have spectral overlap, so by compositing them, I wonder if you’re adding more energy into the scan than there should be.