Simulating Film Stock Dye Sensitivities Pt 3.1

Written By Greg Enright

In pursuit of a better way to mimic the qualities of film stocks, some brilliant guys by the name of Thatcher Freeman and Troy from The Hitchhikers Guide to Colour developed an initial DCTL called the Dye Simulator. I’ve spent countless… I’d say 60+ hours trying to figure out how best to incorporate this into a node tree. Below are my findings…

Prequisite Downloads

If you plan on trying to follow along. Here are some free plugins and tools and other things that will be referenced

Powergrade & More Folder: 

If there are any issues with these, let me know, and I’ll try to update them.

Dye Simulator: 

  • https://github.com/thatcherfreeman/utility-dctls/blob/main/Effects/Dye%20Simulator.dctl

  • https://github.com/thatcherfreeman/utility-dctls/tree/main?tab=readme-ov-file#dye-simulator-dctl

Git Hub DRTs:

Double Dye Sim 3X - Node Tree as of 9/7/24  

Dye Sim targets The Indiana Jones Negative and Print Stock

(Using Node Layers for order)

This node tree functions on 4 levels… 

  • The first takes you back to before the film was exposed to light and so any adjustments made to the digitally recorded log image are akin to adding light or shaping the image on set the day it was filmed.   

  • The next is a macro level adjustment made by setting your film stock and chemical process methods to create a negative image

  • The third is place to do shot-by-shot adjustments with controls that operate on the CMY channels in negative to tweak what is feed into the print sim

  • The fourth is the last Macro level adjustment that is made by setting your print stock and path to display.

Set your two macro choices and then make shot-by-shot adjustments… This tree expects any sort of log footage… I’ve put it on a variety of red, arri, and canon to the same effect.

1. Back on Set Adjustments

Layer 1 - Exposure and Balance

  • N9 - Diagnostics (RGB Chips - Thatcher, Grey Ramp, Gradient Smoothness)

  • N1 - CST (Turned off as Dye Sim expects log footage)

  • N2 - Noise Reduction

  • N3 - Exp/Contrast (LGGO in gamma Linear, also could use HDR global)

  • N4 - Color Balance (LGGO in gamma Linear)

  • N5 - Saturation Controls


Layer 2 Power Windows

How to use Layer 1 & 2 - Think of it as modifying the log footage captured in camera as a last chance at effecting what happened on set before the scene hits the film strip. Do you need to insert a practical light with a burn and dodge power window… Do you need to fix your white balance?


Layer 3 - Your Macro look and film process emulation starts here. I’d split this over two node layers but you can’t bump 3 sources like I have it set up.

  • N1 - Clamp (Makes sure your values are not negative - Thatcher utility)

  • N2 - Linear Exposure Control (You can use HDR Global, I’m using Jed Smith’s Linear Grade)

  • N19 - Lens Filters Compound (one is a blue gen at .15 strength like an 85 tungsten, the other is diffusion)

2. Macro Look A (Your Negative Film Stock)

  • N3 - Contour (Set to LogC3 since its still log footage and thats the option - used mostly for contrast control) N3 is the start of what is hitting the film strip

  • N4 is a compound node that has 3 versions of the dye sim. The numbers are set to Kodak 5247 with min and max shut off for the RGB channels not being observed… Set to Status Density option

  • See in Depth Below

  • N5 is a compound node with film effects (Halation on the Red and Green Channels, Grain on RGB)

  • N6 is a 3 invert nodes that only the channels not selected - Red only inverts G & B, Gonly inverts R & B and Blue only inverts R & G


You have at this point created your Print Negative and processed it… Now on to printing it

3. Printer Light Like Controls - 

These can be your clip level adjustments

  • N13 is Diffusion on the negative image - bleeds 

  • N16 is a feeder compound that lets you do power windows because you can… much more control than a printer light machine

  • N7,8,9 has your Offsets set to 0,0,0 on the primary and I also have Jeds LInear Grade (in effect this is a printer light control to adjust the brightness of your Cyan, Magenta, and Yellow layers.

  • N10, 11, 12 is a Density and Sat control (i’m using MonoNodes Shapers CMY but Color Slice on those colors works as well. 

4. Macro look B (Your Positive Print Stock)

  • N15 is the Printed Dye Sim (Set to A transmittance Status)

  • N14 is a compound with 3 opendrt’s that have been somewhat neutered. It is using Open DRT’s Math to go from DW/I to your output of choice… Changing your in transfer function will greatly effect your image… This pipeline was built with DW/I in mind and seems to have the least breakage in testing. 

  • N17 is Base Con by CKC if you need that extra pop of contrast.

There is an alternate ending that use no DRT which I came up with while making this documentation…Instead of going out via N14, use a parallel mixer followed by an invert and then a little more contrast if you need





Greg Enright
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The Importance of DRT Choice