triangle: A Go repository from petervd

Triangle is a tool to generate image arts with delaunay triangulation. It takes an input image and converts it to an abstract image composed of tiles of triangles.

The technique

First the image is blured out to smothen the 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 resulting 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 tap esimov/triangle
$ brew install triangle

Supported commands

$ triangle --help

The following flags are supported:

Flag	Default	Description
`in`	n/a	Input file
`out`	n/a	Output file
`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	Solid line color
`wf`	0	Wireframe mode (without,with,both)
`stroke`	1	Stroke width
`gray`	false	Convert to grayscale
`web`	false	Output SVG in browser
`bg`	' '	Background color

Background color

You can specify a background color in case of (.png) images with a transparent background 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

Multiple image processing with a single command

You can transform even multiple images from a specific folder with a single command by declaring as -in flag the source folder and as -out flag the destination folder.

$ triangle -in ./samples/ -out ./ouput -wf=0 -pts=3500 -stroke=2 -blur=2 -noise=4

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