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HALD Identity

Creates a special image that contains every colour in a grid and does nothing on its own. Whatever grade you apply to it can be saved as a .cube LUT.

HALD Identity — before / after
In ComfyUI Add Node → ComfyUI-JH-PixelPro → color → HALD Identity
Good for Starting a LUT export, turning any colour-only node chain into a reusable look
Speed Instant. Higher levels make a bigger image (level 12 is 1728 × 1728 px)

When to use it

Think of it as a blank colour chart. It looks like a smooth, multicoloured pattern. If you send it through colour nodes (tone curve, colour balance, …), the pattern changes in exactly the way those nodes change every colour in a photo. LUT Export then reads the graded chart and writes the grade out as a .cube file.

This is the first step of the LUT workflow:

HALD Identity → colour nodes only → LUT Export → .cube file

Colour-only nodes between HALD and Export

The chart only survives colour operations that treat each pixel on its own, such as Tone Curve or Hue/Saturation per Range. Do not blur, sharpen, resize, crop, rotate or add grain: they move or mix the pixels and the exported LUT will be wrong.

Quick start

  1. Add HALD Identity and leave level at 8.
  2. Connect its image output to your grade (for example Tone Curve).
  3. Connect the graded image to LUT Export and wire level from HALD Identity to LUT Export's level input.

The full walk-through is on the LUT Export page.

Settings

Setting Default What it does Tip
level 8 Quality of the LUT. Choices: 4, 6, 8, 10, 12. 8 gives a 64-point cube, the usual standard for creative looks.
Level LUT grid Chart size
4 16 points per side 64 × 64 px
8 64 points per side 512 × 512 px
12 144 points per side 1728 × 1728 px

Outputs:

  • image — the identity chart, a single image.
  • level — the same number as an integer, so you can wire it straight into LUT Export.

Tips from retouching

  • Stay at 8 unless you have a reason. Higher levels give a smoother LUT for extreme grades but make a larger file and use more memory.
  • Always wire level to LUT Export. A mismatch raises an error.
  • Preview the chart before the grade, then again after, to check it still looks like a smooth colour pattern.
Under the hood

For level L the LUT has N = L² points per axis and the chart is L³ × L³ pixels, following the ImageMagick HALD convention. Red varies fastest along x, green along y, and blue steps through the L × L tiles. The tensor is float32 in [0, 1], shape (1, L³, L³, 3). The node offers levels 4, 6, 8, 10 and 12; the underlying function accepts 2 to 16.

Example workflow

LUT Export example workflow. HALD Identity, Tone Curve and LUT Export in a row; a Preview Any node shows the written file path. No input image is needed.