Film Developer – a new Dehancer tool

The conventional analogue approach makes it possible to process film not only using the standard development method, but also by individually configuring the formula of the developer solution and the development process. This allows you to control the gamma curve of the image, the contrast, fog, graininess and even saturation (with several color development processes).

The development parameters are usually adjusted for non-standard shooting conditions. For example, sometimes the image contrast is additionally reduced during development for a winter landscape or portrait with soft filters. This allows you to match the contrasts of the scene, the negative and the photographic paper to achieve soft transitions on the final print or to eliminate clipping in the shadows and the highlights.

Depending on the author’s concept, it may be necessary, on the contrary, to increase the contrast of the negative. For example, a cloudy daytime scene has reduced contrast, which can be increased during development and then amplified when printing.

A special developer formula may also be required for unmarked or expired film. Usually we are talking about hand-rolled black and white negatives, or expired color films of unknown origin. In this case, a small piece of film (about 1-2 frames) is cut from the reel in the dark, then after the first test development, adjustments are made to the processing parameters. The procedure is repeated several times until the desired result is achieved, then the whole film reel is developed in the resulting solution. If there is a large amount of this film, the developer is matched using pre-shot test frames containing, for example, standard color charts.

To fine-tune the film emulation depending on the characteristics of the source material, shooting conditions and creative tasks, we added a new tool to Dehancer called Film Developer that allows you to make your own developer recipe.

Let’s demonstrate how the Film Developer tool works. Since we are going to talk not only about brightness characteristics, but also about saturation, we will use a test image that reflects the perceptual distribution of saturated colors depending on their brightness.

Contrast Boost

This parameter controls the developer contrast. In analogue processes, development contrast is determined by developer temperature and concentration. In Dehancer this parameter can take both positive values (contrast increases) and negative values (contrast decreases).

Contrast Boost = -100

Contrast Boost = +100

Gamma Correction

The concept of gamma curve originally came into the world of digital imaging from the laboratory processing of photographic materials. It is the contrast ratio of a negative, in relation to the exposure time. This parameter determines how much the midtones are shifted towards shadows or highlights.

Gamma correction is possible with any Contrast Boost value other than zero. For maximum illustrative effect, let’s demonstrate the effect with Contrast Boost = +100.

(Contrast Boost = +100)
Gamma Corrector = -50

(Contrast Boost = +100)
Gamma Corrector = +50

Color Separation

The color separation of the negative film is determined by the color filters in the emulsion layers, the sensitisation of each layer and their order in the emulsion. In Dehancer we can control the supposed ‘chemical component’ of the developer, which affects the sensitisation of the emulsion layers.

By default, the Color Separation setting has a maximum value of +100. It affects the image at any Contrast Boost value other than zero. Let’s illustrate the effect of Color Separation when Contrast Boost = +50.

(Contrast Boost = +50)
Color Separation = 0

(Contrast Boost = +100)
Color Separation = 100

When Color Separation value is reduced, saturation of the most intense colors is reduced first, while medium and low saturation colors remain almost unaffected.

Color Boost

Some color development processes, such as K-14 (Kodachrome), allow saturation to be controlled by the properties of the dyes that are introduced into the emulsion at the development stage. In Dehancer, this feature is implemented in the Color Boost parameter, which increases or decreases the overall saturation of the image (not only the most saturated colors, as with Color Separation). This type of color enhancement is gentle and does not lead to clipping, i.e. all colors remain inside the color gamut.

Color Boost = 0

Color Boost = 100

Film practice shows that it is not often necessary to change the development conditions. It is expected that Dehancer users will also need the Film Developer parameter group less often than other tools, so it is collapsed by default.

The correction of the development recipe helps to quickly and efficiently achieve the desired result if:

  1. We are facing a source with an unknown gamma, contrast and color. For example, a Flat or Log video footage from an unknown camera.
  2. We are dealing with a non-standardised format. For example, the D-Cinelike looks different on different DJI drones, depending on the specific camera and exposure conditions. However, the manufacturer does not supply a LUT for interpretation.
  3. There is no dedicated profile for your particular camera in the Dehancer plugin.
  4. The camera profile is available in the plugin, but you are not happy with it or want to make additional adjustments to the interpretation of the source material.
  5. We are dealing with an image with excessive or insufficient contrast, which we want to normalise and make more flexible for further processing.
  6. We want to increase the overall saturation, avoiding oversaturation and color clipping where possible.

Let’s review several examples.

Example 1

D-Cinelike camera footage from a DJI Mini 3 Pro drone.

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To adapt this image to the Prokudin-Gorskiy 1906 (experimental) film profile, it was sufficient to adjust two development parameters: Contrast Boost = 67 and Gamma Correction = 7. No other LUTs or DaVinci Resolve were involved.

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Example 2

Log gamma footage purchased from a video stock. The camera and shooting mode are unknown.

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An example of the interpretation of this image with customised development parameters (contrast and color enhancement, gamma correction) in combination with Kodak Portra 400 film:

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Example 3

The experimental interpretation of the footage in the Log gamma from the RED Helium camera, two approaches. The first option is to use the dedicated camera profile. The second option is to adjust the Film Developer recipe. Both graded with Kodak Vision 3 250D film profile:

RED Log 3G10

IPP2 RWG Log 3G10 Standard camera profile selected in the plugin

Source interpretation using the Film Developer tool

Obviously, manual interpretation does not always provide accurate color reproduction (as when using a dedicated camera profile, which includes parameters for accurate color correction). Nevertheless, this experiment demonstrates that Film Developer is quite capable of working with material in the Log gamma.

In just a few clicks you can get an image that is quite acceptable in contrast, color, and saturation. This approach can be used when the camera is unknown, if you don’t like the camera profile, or as an option for creative development.

Example 4

The source footage is in Rec.709 and has excessive contrast:

Contrast reduction with Film Developer custom formula for Kodak Vision 3 500T film:

Further processing with the standard Dehancer tools – Expand, Film Compression, Print, Film Grain, Bloom.

The main purpose of the Film Developer tool is to simplify the interpretation of a variety of sources within a single node. This is especially true for Dehancer products beyond DaVinci Resolve, meaning Final Cut Pro, Adobe Premiere, Photoshop, Lightroom Classic, Capture One, Affinity Photo, and the iOS application.