Converting an image to use only a limited set of specific colors can be essential for purposes like retro game art, screen printing, or digital optimization. GIMP, a free and powerful image editor, allows you to manually define which colors you want your image to use. This guide will walk you through how to select specific colors from an image and convert it to indexed mode using only those colors.

---

Step 1: Open Your Image in GIMP

1. Launch GIMP.
2. Go to File > Open.
3. Select the image you want to work with and click Open.

---

Step 2: Identify and Pick the Colors You Want

1. Select the Color Picker Tool from the toolbox (looks like an eyedropper), or press O on your keyboard.
2. Click on any color in the image that you want to include in the final palette.
3. When you click a color, it appears as the Foreground color in the toolbox.
4. To save this color:
   • Go to the Palettes dialog (use Windows > Dockable Dialogs > Palettes).
   • Click the hamburger menu in the top right of the Palettes dialog and choose Import Palette.
   • Choose From FG color and name it something relevant (e.g. “My Image Palette”).
5. Repeat this process for each desired color. You can use the Palette Editor to manually build a palette with each selected foreground color by clicking + in the Palettes dialog.

Tip: You can also build your palette more easily using Colors > Info > Color Cube Analysis to scan for frequent colors and then select them using the eyedropper.

---

Step 3: Create a Custom Palette

1. In the Palettes dialog, click + to create a new palette.
2. Give it a name.
3. In the palette editor, click the + button to add the currently selected foreground color.
4. Use the color picker and repeat this process until your palette contains only the colors you want in the final image.

---

Step 4: Convert Image to Indexed Mode Using Your Palette

1. Go to Image > Mode > Indexed.
2. In the dialog that appears:
   • Choose Use custom palette.
   • Select the palette you just created from the dropdown menu.
   • Make sure “Remove unused colors from colormap” is unchecked if you want to preserve all the colors, even if not currently visible.
3. Click Convert.

Your image is now reduced to the specific set of colors you chose.

---

Step 5: Export or Save the Image

1. Go to File > Export As.
2. Choose your file format (PNG is best for indexed images).
3. Click Export and adjust the export settings if needed.

---

Optional: Clean Up with the Bucket Tool or Pencil

After conversion, some areas may have slightly off colors or dithering artifacts. You can manually adjust these using:

• The Pencil Tool to paint with exact palette colors.
• The Bucket Fill Tool with “Fill whole selection” to replace large areas with the correct color.

---

Conclusion

Using GIMP to convert an image to indexed mode with a custom set of colors gives you full control over your color palette. This is especially useful for pixel art, print design, or any use case where precision color management is necessary. With practice, this method becomes a powerful way to stylize or standardize your graphics.