Usage:
distfield input_image output_image output_size
the output size is a single number (only square images are supported). The input image can be many formats (PNG, JPEG, TGA, BMP, PSD etc) courtesy of Sean Barrett's excellent stb_image.c. The output image is always in PNG format and is poorly optimized for size.
The program uses a stupid brute force algorithm, and is therefore slow with large output sizes.