Several websites offer software for download or online use to change images into low-poly graphics. The website Triangulator stands out for its easy-to-use online Delaunay triangulation image generator. You simply upload an image, choose one of three algorithms, and select an output resolution.
The generator treates large color planes as large triangles. Conversely, more detailed features are split into many small triangles. Here, Triangulator compares favorably to other mesh or triangulation programs that produce triangles of much the same size and thus fuzzy-looking borders between colors.
You’ll need to wait patiently for the program to compute high-resolution images. One test image uploaded at 4.2 MB and came out at 25.1 MB. If that’s too large for your purposes, you can compress the image without losing image quality in a program that will accept very high resolution images such as http://compressimage.toolur.com/.
Two of the algorithms (YAPE and YAPE6) come with two sliders to adjust the size and number of triangles (“Minieigen” slider ) or make small tweaks (“Laplacian” slider).
Compare a sample image triangulated with DMesh (first image) and with Triangulator (second image) below.