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Wallpapers

🌄 Customizing Default Wallpapers in Ubuntu-Based ISOs

When building a custom Ubuntu-based ISO using Cubic, you may want to replace default system wallpapers. These wallpapers are often included for branding purposes, so understanding their location, XML configuration, and licensing is critical.

1️⃣ Wallpaper Locations

  • Default wallpapers are stored in:
/usr/share/backgrounds/

  • You may see several images here, often representing:

  • Ubuntu official wallpapers (e.g., “ubuntu-24.04.jpg”)

  • Freely licensed wallpapers (e.g., “Noble.jpg” or “Focal-Landscape.jpg”)

Tip: Only replace wallpapers that are freely redistributable to avoid licensing issues.

2️⃣ XML Mapping Files

  • Wallpapers are often referenced in XML files located nearby, usually in:
/usr/share/gnome-background-properties/

  • Example files:

  • ubuntu-wallpapers.xml → maps the default Ubuntu wallpapers

  • noble-wallpapers.xml → maps freely licensed wallpapers

Purpose of XML:

  • Each XML file defines metadata for the wallpapers, including:

  • File path

  • Name (human-readable)
  • Type (Light, Dark, or Grey mode)
  • Default selection

3️⃣ Editing Wallpapers Safely

There are two ways to replace wallpapers while keeping system behavior intact:

Option A: Keep the XML Filename and Replace the Image
  1. Identify the image you want to replace (e.g., ubuntu-wallpaper.jpg)
  2. Prepare your custom image with the same filename.
  3. Replace the original file in /usr/share/backgrounds/:
sudo cp my-wallpaper.jpg /usr/share/backgrounds/ubuntu-wallpaper.jpg

Effect:

  • XML mapping does not need to be edited.
  • The system will display your custom image while keeping Light/Dark/Grey modes intact.
Option B: Edit the XML File
  1. Open the XML file (e.g., ubuntu-wallpapers.xml) in a text editor:
sudo nano /usr/share/gnome-background-properties/ubuntu-wallpapers.xml

  1. Find the <wallpaper> entries and modify:

  2. <name> → human-readable label (optional)

  3. <filename> → path to your custom image

Example:

<wallpaper>
    <name>My Custom Wallpaper</name>
    <filename>/usr/share/backgrounds/my-wallpaper.jpg</filename>
    <options>zoom</options>
    <pcolor>#000000</pcolor>
    <scolor>#FFFFFF</scolor>
    <shade_type>solid</shade_type>
</wallpaper>

Effect:

  • You can rename wallpapers, add multiple modes, and assign custom metadata.
  • Allows full control over Light, Dark, and Grey modes.

4️⃣ Supporting Multiple Modes (Light/Dark/Grey)

  • Modern Ubuntu and GNOME desktops support three modes:

  • Light Mode → default wallpaper for bright themes

  • Dark Mode → used when the system switches to a dark theme
  • Grey/Neutral Mode → sometimes used for login screens or lock screens