The Formation is the color transformation layer in the Image Stack, between Balance and the effect layers. It sets the image formation applied to the photo.

Image Formations

An image formation is the transformation that turns a camera’s scene-referred signal into a finished, display-referred image.

A digital camera does not record what the eye sees. It records a relative technical signal across a range whose limits are not assumed in advance — the open domain, or scene-referred data. An image formation reduces that signal to a known, bounded range suitable for a screen — the closed domain, or display-referred data. The same conversion can be done many ways; what distinguishes them is intent, not method.

Related transforms in the video industry go by several names: DRT (Display Rendering Transform), ODT (Output Display Transform), show LUT, picture profile, display preparation, color management. Aphera uses the term “image formation” because the transform prioritizes the image. The technical conversion between displays is a separate concern.

Formations apply to RAW images only. On a JPG, the Formation layer is inert and the row shows a warning; see Image Stack.

Options

Set the formation from the Formation menu on the layer’s row. The row is labeled Formation: Aphera 2499 or Formation: Custom LUT. Three options are available:

  • No Image Formation
  • Aphera 2499
  • Custom LUT

Aphera 2499

Aphera’s default image formation. It is engineered to hold up across a wide range of subjects and lighting: portraits, landscapes, architecture, foliage, colored light, dark scenes, very bright scenes, natural light, and artificial light.

In the broadest terms, 2499 governs how red, green, and blue render. Those are the colors viewers recognize most, so their rendering matters most; each can shift warmer or cooler with the scene. The formation includes safeguards that keep the image from breaking.

2499 is a starting point. Combine it with effect layers to build a more specialized rendering — one that may not suit every situation, but works better in the situations it is built for. Shape the broadest adjustments first and the finest last.

When the Aphera 2499 layer is expanded, it exposes its own controls:

  • Base Saturation — the overall saturation of the formation, applied before any other 2499 control. Zero renders the image neutral (grayscale); values above 1 push saturation beyond the default.
  • Desaturate — R, G, B — pulls a single primary toward neutral. At the full value the channel is untouched; lower it to desaturate that primary alone.
  • Density of Highest Saturation — darkens the most saturated colors while near-neutral colors stay essentially unchanged, the way dense film dyes render strong colors darker. Higher values add more density.
  • Hue Shift — R, G, B — rotates the hue of each primary across the whole image. Red: right is warmer (toward orange), left is colder (toward magenta). Green: right is warmer (toward yellow), left is colder (toward cyan). Blue: right is colder (toward cyan), left is warmer (toward magenta).
  • Specular Hue Shift — R, G, B — the same rotation as Hue Shift, applied only to the brightest values. Use it to let highlights render warmer or cooler than the rest of the image.

Custom LUT

Applies a user-supplied 3D lookup table (LUT) as the image formation in place of 2499. A LUT transforms a scene-referred image to display. Files are in .cube format.

  • LUT File — Choose File… selects the .cube file. Once loaded, the file name is shown with a Remove button.
  • LUT Settings — specify the inputs and outputs the LUT expects. If they are not known, ask the author of the LUT.
    • Input Log Function
    • Input Color Space
    • Output Color Space
  • Options
    • Input Gamut Mapping — limits saturation to the working color space.