Colour banding / posterisation issue on LUTs, add a simple “Pre-LUT Desaturation” control (or another HSL module before LUTs)

DxO PhotoLab
1

I keep running into colour banding / posterisation when I apply creative LUTs to photos that are already quite saturated, reds in particular blow out.

Current workaround

  1. Canon R6 Mk II RAW into PhotoLab 8
  2. Do basic exposure tweaks
  3. Turn off the LUT, drop overall saturation in HSL to -50 / -60
  4. Export a 16-bit TIFF
  5. Re-import the TIFF, apply the LUT, then bring saturation back up a touch (Saturation ≈ +5, Vibrancy ≈ +100)

This fixes the banding, but with 1 200 images it’s slow and doubles my disk usage.

Proposed solution

Give us a single desaturation slider, or allow HSL module before the LUT module so we can:

  • pull saturation down,
  • apply the LUT,
  • fine-tune colour,

all in one pass and without extra exports.

See the image before and after this process.

Would save a lot of time and storage. Thanks for considering!

LUT
LUT2067×931 272 KB

2 Likes
2

Please welcome to the forum.
Which LUT did you use?
All color Premium LUTs have some big “jumps” which may produce heavy posterization. The following is an approximation of some Premium LUT action, with each rgb coordinate scaled to [0…63], i.e. black=(0,0,0), white=(63,63,63):
(2, 54, 47) → (27.9, 40.5, 30.1)
(2, 55, 47) → ( 5.7, 31.6, 16.1)
(2, 56, 47) → (47.9, 56.8, 56.8)
(2, 57, 47) → (56.1, 58.8, 59.5)
No comments.
Premium LUTs look like they were invented for very specific purposes, very far from being universal, and pehaps assuming the user tolerates posterization for the sake of some “artistic vision”.

In this respect, LUTs from the Standard family are much safer to use, perhaps except for the “04-Forgotten film”, which is still less “jumpy” than the color Premium ones.

EDIT: Overall, I think it’s better to prepare your own presets, based mainly on HSL and Tone Curve tools, rather than use LUT files. Note that PhotoLab expects LUTs to work in WideGamut colorspace. Adobe’s Cube LUTs are broken by design, since there’s no way to specify working colorspace.