helios_puzzle.go

package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"os"

	"github.com/nfnt/resize"
	"gocv.io/x/gocv"
)

const threshold float32 = .75

func main() {
	full := gocv.IMRead("img/full.png", gocv.IMReadColor)
	defer full.Close()

	hashtag := gocv.IMRead("img/hashtag.png", gocv.IMReadColor)
	defer hashtag.Close()

	result := gocv.NewMat()
	defer result.Close()

	emptyMask := gocv.NewMat()
	defer emptyMask.Close()

	gocv.MatchTemplate(full, hashtag, &result, gocv.TmCcoeffNormed, emptyMask)

	var matches []image.Rectangle

	hashW := hashtag.Cols()
	hashH := hashtag.Rows()

	for col := 0; col < result.Cols(); col++ {
		for row := 0; row < result.Rows(); row++ {
			val := result.GetFloatAt(row, col)
			if val >= threshold {
				rect := image.Rect(col, row, col+hashW, row+hashH)
				matches = append(matches, rect)
				fmt.Println(rect, "=>", val)
			}
		}
	}

	for _, rect := range matches {
		gocv.Rectangle(&full, rect, color.RGBA{0, 0, 0, 1}, 6)
	}

	gocv.IMWrite("output.png", full)

	img, err := full.ToImage()
	if err != nil {
		panic(err)
	}

	bounds := img.Bounds()
	resized := resize.Resize(uint(bounds.Dx()/2), uint(bounds.Dy()), img, resize.Lanczos3)

	out, err := os.Create("output_resize.png")
	if err != nil {
		panic(err)
	}
	defer out.Close()

	err = png.Encode(out, resized)
	if err != nil {
		panic(err)
	}
}