string-art

A C++ implementation of an algorithm to generate photorealistic string art images. See my blog post for details and more examples.

Algorithm animation	Final result

Usage

To compile simply run make.

The script can be run as

string_art input.pgm num_pins opacity threshold skipped_neighbors output.pgm

where

• input.pgm is a square binary “P5” portable graymap image without comments (suggested 512x512),
• num_pins is the number of nails (suggested: 256),
• opacity is the opacity factor, see below (suggested: 0.2, higher value means brighter image),
• threshold is the opacity factor, see below (suggested: 255, higher value means brighter image),
• skipped_neighbors is how consecutive nails can be (suggested 32),
• scale_factor is the scaling factor of the output image (suggested: 8),
• output the output string-art image.

The copy-paste-able version

string_art input.pgm 256 0.2 255 32 8 output.pgm

I used ImageMagick to perform the conversions to/from .pmg format, it is as easy as

magick image.png image.pgm

Opacity and threshold

Opacity and threshold affect the final black/white balance of the picture. Use the following image as a reference.

Some results