▲ Triangle is a tool to generate triangulated image using delaunay triangulation. It takes a source image and converts it to an abstract image composed of tiles of triangles.

The process

• First the image is blured out to smothen sharp pixel edges. The more blured an image is the more diffused the generated output will be.
• Second the resulted image is converted to grayscale mode.
• Then a sobel filter operator is applied on the grayscaled image to obtain the image edges. An optional threshold value is applied to filter out the representative pixels of the resulted image.
• Lastly the delaunay algorithm is applied on the pixels obtained from the previous step.

blur = tri.Stackblur(img, uint32(width), uint32(height), uint32(*blurRadius))
gray = tri.Grayscale(blur)
sobel = tri.SobelFilter(gray, float64(*sobelThreshold))
points = tri.GetEdgePoints(sobel, *pointsThreshold, *maxPoints)

triangles = delaunay.Init(width, height).Insert(points).GetTriangles()

Installation and usage

$ go get -u -f github.com/esimov/triangle/cmd/triangle
$ go install

MacOS (Brew) install

The library can be installed via Homebrew too or by downloading the binary file from the releases folder.

$ brew install triangle

Supported commands

$ triangle --help

The following flags are supported:

Flag	Default	Description
in	n/a	Source image
out	n/a	Destination image
blur	4	Blur radius
pts	2500	Maximum number of points
noise	0	Noise factor
th	20	Points threshold
sobel	10	Sobel filter threshold
solid	false	Use solid stroke color (yes/no)
wf	0	Wireframe mode (0: without stroke, 1: with stroke, 2: stroke only)
stroke	1	Stroke width
gray	false	Output in grayscale mode
web	false	Open the SVG file in the web browser
bg	' '	Background color (specified as hex value)
w	system spec.	Number of files to process concurrently (workers)

Background color

You can specify a background color in case of transparent background images (.png) by using the -bg flag. This flag accepts a hexadecimal string value. For example setting the flag to -bg=#ffffff00 will set the alpha channel of the resulted image transparent.

Output as image or SVG

By default the output is saved to an image file, but you can export the resulted vertices even to an SVG file. The CLI tool can recognize the output type directly from the file extension. This is a handy addition for those who wish to generate large images without guality loss.

$ triangle -in samples/input.jpg -out output.svg

Using with -web flag you can access the generated svg file directly on the web browser.

$ triangle -in samples/input.jpg -out output.svg -web=true

Supported output types

The following output types are supported: .jpg, .jpeg, .png, .svg.

Process multiple images from a directory concurrently

The CLI tool also let you process multiple images from a directory concurrently. You only need to provide the source and the destination folder by using the -in and -out flags.

$ triangle -in <input_folder> -out <output-folder>

Tweaks

Setting a lower points threshold, the resulted image will be more like a cubic painting. You can even add a noise factor, generating a more artistic, grainy image.

Here are some examples you can experiment with:

$ triangle -in samples/input.jpg -out output.png -wf=0 -pts=3500 -stroke=2 -blur=2
$ triangle -in samples/input.jpg -out output.png -wf=2 -pts=5500 -stroke=1 -blur=10

Examples

License

Copyright © 2018 Endre Simo

This project is under the MIT License. See the LICENSE file for the full license text.