Genesis Plugin: A Deep Dive into Bottom-Up Photochemical Film Emulation for Color Grading

Cullen Kelly

Introduction [0:00]

The video introduces "Genesis," a new plugin developed over four years by Cullen Kelly, Dr. Bugdanowitz, and Steve Yedlin. This plugin aims to provide a robust, bottom-up film model, simulating the actual chemistry and behavior of film, rather than a top-down approach that merely mimics a film look. Genesis functions as a photochemical look development tool and a Display Rendering Transform (DRT).

Is Genesis a DRT? [1:30]

Genesis acts as a complete journey for your image, always rendering it into display space. It supports various input spaces, allowing for flexible color management. However, it insists on being the "last mile" in the processing chain, handling the final display transform itself. This means it integrates into existing color management workflows (like DaVinci YRGB Intermediate or ACES) by taking the working space as input and outputting to the display.

Genesis Settings Explained [3:10]

The Genesis plugin is divided into five core sections: Camera, Development, Print, Halation, and Grain.

Camera [3:17]

This section models the initial film exposure.

• Negative Stock: Offers over 40 iconic film negative stocks, enabling users to choose the characteristics of their virtual film.
• Exposure Slider [4:00]: Allows adjustment of the exposure applied to the virtual film camera.

Development [4:17]

This section simulates the film development process.

• Push/Pull [4:19]: A powerful and unique slider that mimics the "push" and "pull" processing in a lab, affecting the contrast of the image.
  • When "exposure compensation" is enabled, it symmetrically adds contrast while maintaining a consistent middle exposure (laboratory aim density).
  • Disabling exposure compensation allows for asymmetrical adjustments, offering creative control over the curve, suitable for looks like day-for-night.
• Inner Layer Effect [4:22]: This slider is unique, allowing users to manipulate the chemical interactions between the stacked red, green, and blue sensitive layers of film.
  • It boosts the designed inner layer effect, which can be thought of as a form of "film saturation," influencing color purity and saturation in a non-traditional, organic manner.
  • This interaction means that adjusting contrast can also subtly affect color and saturation, reflecting real film behavior.

    

• Bleach Bypass (Negative) [4:50]: Simulates the skip-bleach process during negative development, producing a distinct character of desaturation and contrast.
• Neutral Negative Curves [4:59]: These curves influence the color bias in the negative's tone scale.
  • Contrary to a common digital aesthetic of strong split-toning, real film stocks and prints are designed to largely offset each other's color biases to achieve a relatively neutral tone scale, especially around middle gray.
  • Adjusting these curves can either enhance or diminish the inherent (subtle) split-toning, revealing how historical digital intermediates often exaggerated this effect by not properly compensating for the negative's characteristics.

Print [5:03]

This section models the film printing process.

• Printer Lights [5:06]: Provides true printer points with the correct scale and polarity (e.g., increasing red adds cyan).
  • These printer points behave differently from log offsets in digital tools (like Resolve) because they operate within the complex, non-linear "negative to print sandwich."
  • This design allows for robust color "washes" and adjustments without breaking the image or clipping gamut boundaries, making it highly effective for look development and potentially for shot-level balancing.

    

• Print Stocks [5:45]: Includes a wide range of iconic print stocks, some dating back to the 1950s.
• Bleach Bypass (Print) [5:58]: Simulates the bleach bypass effect during print development, yielding a different character of desaturation and contrast compared to the negative-side bleach bypass.
• Neutral Print Curves [6:17]: Similar to neutral neg curves, these adjust the color bias within the print's tone scale, further contributing to the overall neutrality or specific aesthetic.

Display Target [6:37]

This section manages the final output to display.

• Genesis acts as a full color management framework, taking a chosen input space and outputting to various display spaces, including HDR targets (e.g., Rec 2020 PQ, P3 PQ).
• Peak Luminance [6:59]: Allows for stretching or unrolling highlights when working in HDR modes.

Halation and Grain [7:40]

These features add authentic filmic textures.

• Halation [7:42]: Incorporates Steve Yedlin ASC's sophisticated halation algorithms.
  • It provides a very tight and accurate model of real film halation, which is subtle and selective.
  • It activates primarily on bright, high-contrast edges, avoiding the exaggerated or "orange bloom" often seen in less accurate digital halation tools.
  • Includes control for film gauge (e.g., 16mm, 35mm, 65mm), which influences the scatter and subtlety of the halation effect.
  • Performance Note: Halation is the most processor-intensive part of the plugin due to its complex algorithm; real-time playback may require lower resolution timelines or proxies.

    

• Grain [8:36]: Utilizes Steve Yedlin's empirically derived grain algorithms.
  • Offers control over grain strength and saturation.
  • The grain's inherent color varies by film stock (e.g., 5219 Vision 3 stock has specific saturation levels, while daylight stocks are less saturated).
  • Users can adjust saturation for aesthetic preferences.
• Curve Plot and LUT Export [8:43]: The plugin displays a 1D curve representing the net effect of all applied settings on contrast and tone scale. It also allows for LUT export.

Genesis Compatibility with Other Workflows [9:30]

Genesis is designed to be fully compatible with any existing color management framework, including ACES and Dolby Vision. The key is that Genesis acts as the DRT (Display Rendering Transform). This means users can work in their preferred color space (e.g., ACEScct) for grading, VFX turnovers, etc., but Genesis handles the final conversion to the display, imparting its unique filmic character.

Printer Lights in Genesis [11:00]

The printer points in Genesis function differently and more authentically than generic printer light tools found in other software like DaVinci Resolve.

• They exist within a complex "negative to print sandwich" where multiple non-linear processes occur before and after their application.
• This design results in a more organic and less "breakable" response, allowing for dramatic color "washes" without introducing harsh clipping or gamut issues.
• This behavior mimics how traditional color timers worked with film, where adjustments to printer lights influenced the overall look in a cohesive, interactive manner.

Genesis Curve [16:06]

The displayed curve represents the net 1D contrast and color bias of the entire film system (negative, development, and print). It provides a visual overview of how various settings, such as push/pull, bleach bypass, and neutral curves, collectively shape the image's tonal response and color balance. It does not illustrate the complex 3D color space transformations.

Offset for Correction vs. for Look Creation [18:10]

In photochemical look development, everything interacts organically, unlike digital tools (like Contour) which allow for highly targeted, isolated adjustments.

• For example, in real film, increasing contrast will always have associated interactions with color, saturation, and purity, rather than just a linear change in luminance.
• This inherent interactivity of film layers (e.g., how stimulating one color layer affects others) is modeled in Genesis, ensuring smoothness and preventing the "broken" colors that can occur with digital manipulation of extreme primaries (e.g., a pure, unmixed red light).
• This means changes in Genesis often result in interesting, unexpected "collaborative" responses from the image, guiding the colorist in a more exploratory way.

Contour and Genesis Combined [22:10]

Contour is described as a best-in-class digital look development tool that excels at targeted, precise adjustments (e.g., increasing density in specific red stripes). Genesis is a first-of-its-kind photochemical look development tool that provides a robust, interactive, and organic filmic foundation.

• The ideal workflow involves using Genesis to establish a broad, organic filmic look, leveraging its interactive properties.
• Subsequently, Contour can be used to stack targeted, digital refinements on top of the Genesis base, allowing for specific adjustments without unwanted secondary effects that film chemistry would introduce.

Color Management in Genesis [28:00]

Genesis seamlessly integrates into existing color management pipelines by replacing the final output transform. Instead of a standard Resolve Color Space Transform (CST) to display, Genesis takes the working space (e.g., DaVinci YRGB Intermediate, ACEScct) as input and applies the full film model before outputting to the target display space (e.g., Rec.709 Gamma 2.4). This ensures the filmic rendering is applied correctly within the color-managed environment.

Negative vs. Positive [29:32]

• Negative: The film stock used in the camera to capture and encode the image. Genesis offers a wide array of negative stocks.
• Print: The stock onto which the negative is printed for display. Genesis also provides various print stocks.
• These two components are intrinsically linked; a negative emulation without a corresponding print emulation is conceptually difficult and doesn't represent a complete film system. The plugin correctly models this symbiotic relationship.

Genesis Settings Deep Dive [31:02]

To effectively use Genesis, two principles are helpful for orientation:

• 1. Film Stock Families [32:33]: Instead of learning each of the 50+ individual negative and print stocks, focus on the "families" (e.g., Vision 3, EXR, Fuji). Stocks within a family will have subtle variations, while shifts between families will show more significant aesthetic differences, particularly in contrast and tone scale.
• 2. Tooltips [35:08]: Every slider and UI element in Genesis includes a tooltip to provide immediate information on its function.

Push/Pull (Revisited) [35:30]

• By default, the push/pull slider adjusts both exposure and development symmetrically to increase or decrease contrast while maintaining the image's middle gray point (laboratory aim density).
• Disabling "exposure compensation" allows independent control over exposure and push/pull, enabling more extreme or artistic curve shaping, useful for effects like day-for-night.

Inner Layer Effect (Revisited) [36:31]

• This feature models the physical interaction between the stacked dye layers of film (red, green, blue sensitive). Modern film stocks can have a dozen active layers controlling inter-image effects.
• Adjusting this slider boosts these designed interactions, primarily affecting color purity and saturation in a unique, non-linear way, akin to "film saturation."
• This interactivity ensures that even contrast adjustments will subtly influence color, reflecting the organic nature of film.

Bleach Bypass (Revisited) [39:13]

• The plugin accurately models the bleach bypass process (also known as skip bleach), where the bleach step in negative development is skipped.
• This creates an iconic high-contrast, desaturated look that is distinct from print-side bleach bypass and other digital desaturation methods.

Neutral Negative/Print Curves (Revisited) [40:33]

• Historically, film systems (negative + print) were designed to achieve a relatively neutral tone scale, especially for critical elements like skin tones.
• The "cool shadows/warm highlights" split-toning often associated with "filmic" looks in digital grading is often an exaggeration that emerged from applying print film emulations to digital negatives without the proper compensating negative curves.
• Genesis accurately models the complementary color biases of negative and print stocks, allowing users to either maintain a neutral balance or intentionally introduce specific color biases, providing a deeper understanding of true filmic behavior.

  

Halation and Grain [48:00]

Halation [53:50]

• Genesis utilizes Steve Yedlin's acclaimed halation algorithm, known for its accuracy and subtlety.
• It models true film halation, which is not simply an "orange bloom" but a complex interaction of light scatter within the film emulsion.
• The halation is highly selective, activating predominantly on bright, high-contrast edges, providing an authentic look without the exaggerated effects seen in many digital counterparts.
• Users can adjust the film gauge (e.g., 16mm, 35mm, 65mm) to control the spread and character of the halation. Larger gauges result in finer detail and less noticeable halation.
• Performance Impact: Due to the algorithmic complexity, halation is the heaviest component of the plugin and may require lower playback resolutions or proxies for smooth real-time performance.

Grain [59:08]

• The grain in Genesis is empirically derived from actual film stocks, providing an authentic and dynamic texture.
• Controls allow for adjusting the strength and saturation of the grain.
• The inherent color of the grain varies by stock (e.g., Vision 3 5219 has a specific saturation, while daylight stocks might be less saturated), giving users precise control over its aesthetic contribution.

Fuji Stocks and Negatives [1:01:20]

Genesis includes a comprehensive selection of Fuji negative and print stocks, offering distinct characteristics compared to Kodak. The speaker expresses a particular fondness for Fuji 3523 print stock, noting its "snap" and unique character.

Ending [1:04:00]

Cullen Kelly concludes by expressing his passion for the Genesis plugin, which represents years of research and collaboration. He highlights his personal satisfaction as a user, having sought such a film emulation solution for nearly a decade. He confirms that Genesis will be available as a one-time purchase with payment plan options, not a subscription. The product will be offered in different tiers, from a basic DRT offering to a full version with all the photochemical look development controls demonstrated.