This tutorial is based on a tip from Raphael Quinet on the GIMP-User mailing list:
A point cloud image is one where an original color (or grayscale) image is converted into a series of black dots. These images can be created with a simple conversion to index mode using a single bit depth with dithering enabled. Start with your original photograph, then:
- Select Image->Mode->Indexed to convert the RGB image to an indexed palette.
- In the Indexed Color Conversion dialog, set the Colormap option to use a black and white (1-bit) palette
- Select Floyd-Steinberg color dithering in this dialog as well.
- Finally, click the Convert button to transform the photograph to a point cloud image.
If the original photo is too small to produce sufficient detail in your point cloud, try scaling it up before converting to an indexed image. Select Image->Scale Image and double or triple the width and height before going to Image->Mode->Indexed.
You may also want to play with the overall brightness or contrast ofthe image before converting it Indexed mode. The Curves, Levels and Brightness-Contrast dialogs (found under the Colors menu) will all be of use in this case.
The Newsprint filter might produce what you’re looking for in a one-step process, though it’s less like an image cloud than this process. You can find the Newsprint filter under Filters->Distorts->Newsprint.