**How to Remove All the Colors Except One in GIMP**

  - Open a regular color image in GIMP by clicking "File" then "Open" and selecting the image you want to manipulate.
  - Click "Tools," "Selection Tools" and "By Color Select." Click on the color you want to keep in your image.
  - Click "Select" then "Invert" to select everything in the picture except for that color.
  - Click "Color" and "Hue-Saturation" to bring up the hue and saturation box. Slide the "Saturation" bar all the way to the left to turn everything selected to black and white.
  - Click "Select" and choose "None" to see your new image with only one color left.