triangle

README

Triangle is a tool to create image arts using the delaunay triangulation technique. It takes an image as input and it converts to 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 we apply the delaunay algorithm 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 github.com/esimov/triangle/cmd/triangle
$ go install

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
max	2500	Maximum number of points
noise	0	Noise factor
points	20	Points threshold
sobel	10	Sobel filter threshold
solid	false	Solid line color
wireframe	0	Wireframe mode (without,with,both)
width	1	Wireframe line width
gray	false	Convert to grayscale

Setting a lower points value, the resulted image will be more like a cubic painting. You can even add a noise factor, giving a more artistic, despeckle like result for the final image.

In case the gray filter is set as true the resulting triangulated image will be converted to grayscale mode.

Here are some examples you can experiment with:

$ triangle -in samples/clown_4.jpg -out output.png -wireframe=0 -max=3500 -width=2 -blur=2
$ triangle -in samples/clown_4.jpg -out output.png -wireframe=2 -max=5500 -width=1 -blur=10

You can even transform multiple images from a specific folder with one command, concurently, by specifying as -in flag the source folder and as -out flag the destination folder. Example:

$ triangle -in ./samples/ -out ./ouput -wireframe=0 -max=3500 -width=2 -blur=2 -noise=4

Below are some of the generated images:

License

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

Documentation

Index

• Constants
• func Grayscale(src *image.NRGBA) *image.NRGBA
• func Noise(amount int, pxl image.Image, w, h int) *image.NRGBA64
• func SobelFilter(img *image.NRGBA, threshold float64) *image.NRGBA
• func Stackblur(img *image.NRGBA, width, height, radius uint32) *image.NRGBA
• type Delaunay
  • func (d *Delaunay) GetTriangles() []Triangle
  • func (d *Delaunay) Init(width, height int) *Delaunay
  • func (d *Delaunay) Insert(points []Point) *Delaunay
• type Node
• type Point
  • func GetEdgePoints(img *image.NRGBA, threshold, maxPoints int) []Point
• type Processor
  • func (p *Processor) Process(file io.Reader, output string) (*os.File, []Triangle, []Point, error)
• type Triangle

Constants

const (
	WITHOUT_WIREFRAME = iota
	WITH_WIREFRAME
	WIREFRAME_ONLY
)

const POINT_RATE = 0.875

Functions

func Grayscale

func Grayscale(src *image.NRGBA) *image.NRGBA

Convert image to grayscale.

func Noise

func Noise(amount int, pxl image.Image, w, h int) *image.NRGBA64

Apply a noise factor, like adobe's grain filter

func SobelFilter

func SobelFilter(img *image.NRGBA, threshold float64) *image.NRGBA

Detect image edges. See https://en.wikipedia.org/wiki/Sobel_operator

func Stackblur

func Stackblur(img *image.NRGBA, width, height, radius uint32) *image.NRGBA

Types

type Delaunay

type Delaunay struct {
	// contains filtered or unexported fields
}

func (*Delaunay) GetTriangles

func (d *Delaunay) GetTriangles() []Triangle

Get the generated triangles.

func (*Delaunay) Init

func (d *Delaunay) Init(width, height int) *Delaunay

func (*Delaunay) Insert

func (d *Delaunay) Insert(points []Point) *Delaunay

Insert new triangles into the delaunay triangles slice.

type Node

type Node struct {
	X, Y int
}

type Point

type Point struct {
	// contains filtered or unexported fields
}

func GetEdgePoints

func GetEdgePoints(img *image.NRGBA, threshold, maxPoints int) []Point

Get the edge points after the Sobel filter has been applied.

type Processor

type Processor struct {
	BlurRadius      int
	SobelThreshold  int
	PointsThreshold int
	MaxPoints       int
	Wireframe       int
	Noise           int
	LineWidth       float64
	IsSolid         bool
	Grayscale       bool
}

Processor : type with processing options

func (*Processor) Process

func (p *Processor) Process(file io.Reader, output string) (*os.File, []Triangle, []Point, error)

Process : Triangulate the source image

type Triangle

type Triangle struct {
	Nodes []Node
	// contains filtered or unexported fields
}