In a previous post of mine, I mentioned how I sped up my workflow by ignoring the auto-pickers in the AgX module, and treating the module like a “digital film stock”. I want to explain that idea in a bit more depth as well as provide some additional tips on how I use the module. Either way, I hope it can be thought-provoking.
What do I mean by “Digital Film Stock”
Film Stocks are, in essence, a physical tone-mapper that photographers use, or misuse 
, to accomplish their creative intent. It takes in light from the scene, and converts it into a physical image/negative on the display medium (the film itself before enlarging/printing).
Film stocks all have their unique looks based on their chemistry/tuning, and this is one thing that makes them so fun. You take a picture, and before you even develop it, much of the image’s characteristics/dynamics/colors are already semi-determined by the very nature of the film stock.
The goal of a “digital film stock”, or DFS, is to provide a similar set of unique look characteristics and/or built-in color shifts, in an easy to use format, while enabling the end user to experiment, manipulate, or create their own DFS as they please.
This is already possible and done via styles, but the issue with styles is that they are not entirely simple. There are pitfalls one can fall into unless they are familiar with how styles work. Module presets, on the other hand, are pretty much foolproof.
This is where the AgX module comes in.
Using AgX as a DFS
There are few things I consider when designing a DFS:
- Light Dynamics:
- Dynamic Range (How many stops of light will the DFS be built to handle?)
- Mid-tone Contrast
- Highlight/Shadow compression
- Target White/Black
- Colors:
- What color shifts do we want, if any?
- Overall saturation level?
Let’s go through each point and create a DFS using AgX.
Pick a Good Reference Picture
A good reference image is one that
- Covers a relatively wide dynamic range (could contain pure black/pure white after adding some contrast)
- Has some amount of midtones (There should be some kind of midtone-ish subject matter preferrably)
- Has a wide range of color hues in it (so that we can accurately assess our DFS on various colors).
Set the Initial Exposure
Set the exposure to a good place, based on your taste.
AgX: Input Dynamic Range
Now it is time to set the input dynamic range in AgX.
This is roughly how much data you are expecting your DFS to handle as input. This maps roughly to the final dynamic range of your DFS, but is not exactly the same (Some dynamic range is “lost” after adding contrast, increasing shoulder/toe power, etc.). You can leave it wide open to maximize the digital capabilities, or you can narrow it in order to create a DFS with a narrower dynamic range.
Here are two examples, one with -4 to 4 EV input exposure range, and one with -10 to 10 EV input exposure range. Immediately, you can see what this does to the image. Take a look at how the “-4 to 4” version is practically clipping already. This is important to understand: If you select a wider input Dynamic Range, you will be able to boost contrast more, before clipping. On the other hand, narrow dynamic range films/DFS tend to provide a naturally dramatic look.
In this case, I will go with something more reasonable: -6 to 6 EV input exposure range. My goal is to avoid clipping at this stage, since further steps will continue narrowing my effective dynamic range.
AgX: Contrast
This is a crucial step. Set shoulder and toe power to 1. We are setting the contrast primarily based on our mid-grey subject, NOT on the shadows and highlights. Setting the power sliders to 1 helps me judge only the contrast change occurring in the midtones. Contrast in the shadows and highlights will be handled in the next step.
AgX: Shoulder & Toe Power
Adjust shoulder and toe power to taste while keeping these things in mind:
- Shoulder Power: Increases the contrast in highlights, while crushing ultra highlights. Overdo it and you get sort of an HDR look. Keep it low for a more filmy look.
- Toe Power: Increase to bring out some additional definition in the shadows, while crushing low-shadows into the darkness.
I ended up going pretty moderate on both power sliders. I didn’t want to absolutely crush the shadows, and I did not want the HDR look in the highlights. - Increasing the power of the shoulder and/or toe significantly, will reduce your “effective dynamic range” (The number of stops between minimum and maximum brightness).
AgX: Shoulder & Toe Start
Increasing the shoulder start and toe start sliders increases the linear midtone latitude/range of your DFS, meaning that you are increasing how much of your midtone range is at peak contrast. In addition, you are effectively hardening the “knee” of both the highlights and/or shadows. This means that the transition from peak contrast(in linear part of the curve) to extreme low contrast(in extream highlights/shadows) is much faster when it does happen.
Here are some things to keep in mind when setting your shoulder & toe start positions:
- In analog film, the transition from midtones to extreme highlights is generally smooth, while the transition from midtones to extreme shadows is generally faster.
- In some digitally processed images, the transition from midtones to highlights is very harsh. You can avoid this by keeping the shoulder start value low.
- Increasing the start positions for the shoulder & toe further reduces your “effective dynamic range”. If you want to know what your minimum available dynamic range is at the current contrast, increase the shoulder and toe start values to 100%.
For my DFS, I increased the toe start slightly to increase my shadow definition and crush the extreme shadows a little more.
AgX: Target White, Target Black
Fairly Straightforward. Tips:
- Increase target black to get the faded black look from analog film
- Decrease target white to get the soft white look from movies.
- Don’t touch this if you want to maximize your dynamic range and preserve pure black/white.
- Increasing target black or decreasing target white will decrease your effective dynamic range.
I ended up bringing up the blacks a little and decreasing the target white as well. I think this helps create a DFS that is naturally unifying and glues things together. It helps remove the distraction of details in the shadows and highlights. Feel free to go the other way and maximize image clarity.
AgX: Color Balancing with Primaries
This is a tricky one. You can ignore it, or dive deep into it. If you want to add some color shifting to your DFS, Here is some tips and how I would go about it:
- Before you start, reset all primaries adjustments: 0 attenuation, 0 rotation, and same for boost and negative rotation.
- If you want to do something similar to film, then take a look at your favorite film’s datasheet. There is often an RGB response curves showing how the three different color layers react with the same amount of exposure. You can emulate this by adjusting the attenuation of your input red, green, and blue primaries inversely and then boosting then equally back up to make up for the saturation loss.
- For example, Kodak Portra has blue, green, and red densities at a ratio ~4:3:1. You can emulate this by setting your attenuation sliders to Red: 75% (1/4th density), Green: 25% (3/4ths density), Blue: 0%(100% density). You can then add this purity back in, while maintaining the rgb ratio, by increasing the output red, green, blue boost sliders by 33% each (There was a total decrease of ~100 percentage points, and now a total boost of ~100 percentage points).
- You will notice that you lose some overall saturation at this point. You can boost overall purity more with the “master purity boost” slider. In my case I found a value of 175% offset the overall saturation loss.
AgX: Hue Shifting with Primaries
We continue the modification of color, now with the rotational sliders in the primaries section of AgX. Here are some tips:
- One great way to see the effect of all this is to use the Vector scope to see the overall effect.
- If you want to squish the hue in a similar way to many analog film stocks, then rotate red towards orange a little, green towards yellow a bit, and blue towards cyan slightly more.
- Or forget emulating analog, and go crazy.
AgX: Saturation
Simple: boost saturation to taste. Keep in mind that this is meant to be generally applicable DFS, not ultraspecific to THIS PHOTO.
DFS Application Examples
Here are some examples of this exact DFS (AgX preset), applied to some other images of mine. Exposure, Crop, AgX. That’s it.
Closing thoughts
The beauty of this method is that you never know exactly what you will get at the end. I was genuinly suprised at how this DFS looked on every image I threw at it at the end. Of course I can refine any of those edits further and tweak things, or throw some additional modules on them, but I don’t have to. If I want, I can just enjoy what the DFS gives me.
If you want to try this AgX Digital Film Stock yourself, you can download it below:
agx_digital_film_stock_example.dtpreset (1.2 KB)
Let me know what you think of this enormously long writeup, if you got anything out of it, if you think any of this has merit, or if you hate it with every cell in your body 
