Create Procedural Starry Night Sky in GIMP

Creating a realistic starry night sky procedurally in GIMP is an efficient way to generate high-resolution space backgrounds without relying on external stock photos. By combining built-in noise generation filters, threshold adjustments, layer blend modes, and gradient maps, you can create fully customizable star fields and glowing nebulae completely from scratch.

Step 1: Set Up the Canvas and Base Layer

  1. Open GIMP and create a new image (File > New). Set your desired resolution (e.g., 1920x1080 or 3840x2160 for high definition).
  2. Set the foreground color to pure black (#000000) and fill the background layer using the Bucket Fill Tool.
  3. Name this layer Deep Space.

Step 2: Generate the Base Starfield

  1. Create a new transparent layer above the background and name it Small Stars.
  2. Go to Filters > Noise > CIE lch Noise (or RGB Noise).
  3. Maximize the noise amount (adjusting lightness and chroma) so the entire canvas is covered in dense static.
  4. Go to Colors > Threshold.
  5. Drag the left slider far to the right until most of the white noise disappears, leaving only scattered tiny white dots across the black background. Click OK.
  6. Set the layer mode of Small Stars to Screen or Addition.

Step 3: Add Larger Stars and Glowing Points

  1. Create another new transparent layer and name it Bright Stars.
  2. Fill the layer with black, then apply Filters > Noise > Solid Noise. Set the X and Y size parameters low (around 2.0 to 4.0) with high detail.
  3. Open Colors > Threshold again, pushing the slider right until only a few dozen sparse dots remain.
  4. Soften these stars by going to Filters > Blur > Gaussian Blur and applying a radius of 1.0 to 2.0 pixels.
  5. (Optional) Apply Filters > Light and Shadow > Sparkle with a low intensity to give selected bright stars an authentic lens flare effect.
  6. Set the layer mode to Screen.

Step 4: Generate Procedural Nebula Dust

  1. Create a new transparent layer named Nebula.
  2. Go to Filters > Noise > Solid Noise. Enable Turbulent, maximize the detail level, and adjust the X/Y scaling to create cloudy, organic patterns.
  3. Go to Colors > Curves or Colors > Levels to increase the contrast, creating clear gaps of dark space between the dense dust clouds.
  4. Add color to the nebula by going to Colors > Map > Gradient Map and selecting a cosmic gradient (e.g., Deep Sea, Purples, or Fire), or by using the Colorize tool to apply blues, purples, and magentas.
  5. Change the Nebula layer mode to Screen, Color Dodge, or Soft Light, and lower the layer opacity to 40%–70% to blend it smoothly into the stars.

Step 5: Final Adjustments

  1. To add depth, ensure the layer stack is ordered from bottom to top: Deep Space, Nebula, Small Stars, and Bright Stars.
  2. Add a new transparent layer on top, set its mode to Overlay, and paint subtle radial highlights using a large, soft brush with cyan or violet to adjust ambient space lighting.