Golang : Image to ASCII art example

This tutorial is just for fun and want to relive my DOS programming days for a while. In this tutorial, we will learn how to convert black and white image to ASCII ART.

The code below with generate the following ASCII ART. If you are running this from a terminal, you will need to adjust the terminal size till you can see the ASCII properly. Happy coding!

golang ASCII art image

The code :

 package main

 import (

 func main() {

 // Create an new image with text data
 // From https://github.com/llgcode/draw2d.samples/tree/master/helloworld
 // Set the global folder for searching fonts

 width := 100
 height := 70

 // Initialize the graphic context on an RGBA image
 img := image.NewRGBA(image.Rect(0, 0, width, height))

 // set background to white
 white := color.RGBA{255, 255, 255, 255}
 draw.Draw(img, img.Bounds(), &image.Uniform{white}, image.ZP, draw.Src)

 gc := draw2d.NewGraphicContext(img)


 // Set the font Montereymbi.ttf
 gc.SetFontData(draw2d.FontData{"Monterey", draw2d.FontFamilyMono, draw2d.FontStyleBold | draw2d.FontStyleItalic})
 // Set the fill text color to black


 text := "WE LOVE"
 gc.FillStringAt(text, 0, 20)

 text = "GOLANG!"
 gc.FillStringAt(text, 0, 40)

 // create a new blank image with white background
 newImg := imaging.New(width, height, color.NRGBA{255, 255, 255, 255})

 //paste the text to the new blank image
 newImg = imaging.Paste(newImg, img, image.Pt(10, 20))


 //err = draw2d.SaveToPngFile("./ean.png", newImg)
 //if err != nil {
 // fmt.Println(err)
 // os.Exit(1)

 // convert image to ASCII ART

 var str []string

 for y := 0; y < 70; y++ {
 for x := 0; x < 100; x++ {
 r, g, b, _ := newImg.At(x, y).RGBA()
 rgb := fmt.Sprint(r + g + b)


 if rgb == "196605" { // use -1677216 for all colors ??
 str = append(str, " ")
 } else {
 str = append(str, "#") // if not blank, put # sign

 if strings.TrimSpace(strings.Join(str, "")) == "" { // continue till end



The next challenge for you is to convert a full colored image to ASCII art with Golang. Try it out !

NOTE : For some odd reason, the luximbi.ttf font from https://github.com/llgcode/draw2d.samples/tree/master/helloworld cannot be used. Therefore, I've replaced it with the Monterey font.

You can get the Monterey font from http://www.1001freefonts.com/monterey.font , unzip the zip file and rename the MontereyFLF.ttf to Montereymbi.ttf with this command and execute the code above in the same directory as the 'Montereymbi.ttf' file.

>cp MontereyFLF.ttf Montereymbi.ttf

References :




By Adam Ng

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