go get https://github.com/qeesung/image2ascii

package main

import (
	"fmt"
	"github.com/qeesung/image2ascii/convert"
	_ "image/jpeg"
	_ "image/png"
)

func main() {
	fmt.Print(convert.ImageFile2ASCIIString("example/images/baozou.jpg", &convert.Options{
		Ratio: 0.5,
	}))
}