Technical Guides

Color Management

Lumi-o is configured to work out-of-the-box. As long as you are working on an image with 16-bit or greater precision, the software is already set up to use the default bundled soft-proofing (CMYK) and built-in sRGB profiles; it should all just work without any configuration.

For those needing deeper control, this guide explains Lumi’s core color management model, the difference between an image profile and a soft-proof profile, where the controls live, and exactly how the default profiles bundle with the application.

Quick Summary

Lumi uses three different profile roles:

  1. Image working profile

    • Defines what the image’s RGB or grayscale numbers mean.
    • Used for assign/convert operations.
    • Typical examples: built-in sRGB, Adobe RGB.

  2. Display profile

    • Describes your monitor.
    • Used to show the image correctly on your screen.
    • Usually provided by the system or chosen in Preferences.

  3. Soft-proof profile

    • Simulates another output device or print condition.
    • Does not redefine the image’s pixel values.
    • Typical examples: CMYK press profiles such as CoatedFOGRA39.

Image Profile vs Soft-Proof Profile

Image Profile

Use this when you want to tell Lumi what color space the image is actually in.

Two common operations:

  • Assign profile

    • Changes the profile label attached to the image.
    • Does not convert pixel values.
    • Use only when the pixel numbers are already in that profile’s space.

  • Convert to profile

    • Converts pixel values from the current image profile to a new one.
    • Use when you want the image to truly move into a different working space.

Menu locations:

  • Image > Color Management > Assign Color Profile…
  • Image > Color Management > Convert to Color Profile…

Soft-Proof Profile

Use this when you want to preview how the image would reproduce on a target device or print condition.

Soft-proofing:

  • leaves the image working space alone
  • changes the preview pipeline
  • can mark out-of-gamut colors
  • is intended for preview, not reassignment of image data

Menu locations:

  • Image > Color Management > Soft-Proof Settings > Choose Soft-Proof Profile…
  • Image > Color Management > Soft-Proof Settings > Rendering Intent
  • Image > Color Management > Soft-Proof Settings > Black Point Compensation
  • View > Color Management > Enable Soft-Proof Preview
  • View > Color Management > Mark Out of Gamut Colors

How To See The Soft-Proof Preview

There are two main entry points for toggling soft proofs.

1. View Menu

Use:

  • View > Color Management > Enable Soft-Proof Preview

This turns the preview simulation on or off for the current display.

2. Status Bar Toggle

Lumi also exposes soft-proofing directly in the bottom status bar.

  • Left-click (toggle): enable or disable proof colors
  • Right-click: open the soft-proofing popover where you can tweak:
    • current profile
    • profile chooser
    • rendering intent
    • black point compensation
    • out-of-gamut marking
⚠️
Important Note on Precision Soft-proof preview is only enabled for 16-bit and 32-bit images. For 8-bit images, the toggle is disabled and Lumi will prompt you to convert precision to a higher depth first before previewing colors accurately.

Preferences and Defaults

Global defaults live in:

  • Edit > Preferences > Color Management

Relevant sections:

  • Manual Monitor Profile
  • Preferred RGB profile
  • Preferred grayscale profile
  • Soft-Proofing

Current Lumi defaults

Working Spaces

Bundled working-space ICCs currently offered from the shared data folder:

  • AdobeRGB1998.icc
  • AppleRGB.icc

For standard sRGB work, Lumi also provides a built-in sRGB working profile internally.

Soft-Proof Defaults

Bundled soft-proof profiles currently installed:

  • CoatedFOGRA39.icc
  • USWebCoatedSWOP.icc
  • JapanColor2001Coated.icc

When available, CoatedFOGRA39.icc is used as the default bundled soft-proof/CMYK reference profile.

Practical Workflows

For painting and normal screen work

  • Keep the image in built-in sRGB or another valid RGB working space.
  • Let Lumi use the system monitor profile if available.

For print preview

  • Keep the image in its standard RGB working space.
  • Choose a soft-proof profile that matches the target print condition (e.g. FOGRA39).
  • Enable soft-proof preview.
  • Optionally enable gamut warnings to see clipped rendering intents.
AppImage