Diachromie: introduction

Diachromie is an OpenFX plugin designed to apply robust color modifications for look creation. These looks are scene-referred, meaning they can be seamlessly applied and reused in any modern workflow that relies on scene-referred working color spaces, such as contemporary color-managed workflows.

It brings together a set of mathematical tools that influence contrast and color rendering to create aesthetic distortions in the color volume.

Diachromie is not a color grading tool in the traditional sense—it does not replace the work of a colorist, who remains essential in fully unlocking the potential of each image. Instead, it serves as a refinement and creative tool, helping to develop and maximize a unique color palette for every project.

The looks achieved with Diachromie are highly robust, holding up against a wide range of lighting and color conditions encountered during production, without causing look breakage or revealing hidden flaws that might go unnoticed during the look creation phase.

Unlike a look confined to a LUT, any look created within Diachromie is parametric—it can be adjusted at various stages of image production. This flexibility extends all the way to color grading, where the look remains a set of plugin parameters, fully accessible if needed to fine-tune the visual rendering until the final stage of post-production.

User guide

Workflows and project configuration

Please refer to this page and chapter.

1D Transformations

The 1D Transformations are global transformations that affect the whole image. These are simple transformations that can be represented by a set of 3 curves, one for each color channel. The following 1D transformations are available:

• a contrast curve drawing tool
• a color tone curves tool

Contrast

The contrast curve is fully parametric and continuous. Its pivot point is the neutral grey, so that modifying the curve will have no influence on the exposition of a standard image. By shaping its toe and shoulder, you can define the proper tonal distribution of the image. An extra “mid push” parameter can create complex behaviors in the midlights area, without breaking the continuity of the curve.

The curve can be applied to the R, G, and B channels, or only luma, or a blend of both.

mid push compensate | Introduces a bump in the midlights, which gives more depth in the midtones and the faces.

👉 if mid push compensate is enabled, changing the mid push value will also change white offset and black offset to compensate the induced exposure shift. Keep a reference of the curve before acting on this slider if you want to come back to it. | | shoulder rolloff | Adjusts how soft or hard the transition to the shoulder should be: -1 = softest shoulder 1 = hardest shoulder | | toe rolloff | Adjusts how soft or hard the transition to the toe should be: -1 = softest toe 1 = hardest toe | | mid push compensate | If this feature is enabled, any change on mid push will be compensated on the rest of the curve, to avoid any exposure shift that the mid push would otherwise generate. | | luma blend | Allows you to control the effect of the contrast curve on color saturation: 0 = contrast transformations will be applied on all 3 RGB channels. An increase in contrast will increase saturation 1 = contrast transformations are only applied to the luma. Increasing the contrast will reduce the perceived saturation, and vice-versa. | | blend | Classic modulation of all contrast transformations: 0 = the contrast curve has no effect on the image 1 = the contrast curve has full effect on the image | | exposure | The tools of this submodule significantly change the neutral gray. They are applied first in the plugin’s order of operation and aren’t affected by the blend sliders above. | | flare | Equivalent to optical flare. It will affect the low lights more than the highlights. Lifting or crushing the blacks before the contrast curve is applied. | | exposure | Graduated in EV (stops), equivalent to actual exposure change on set. |

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You can display the contrast curve with the MONITORING TOOLS.

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Color tone curves