Compresses png files to 50% their original size using nearest-neighbor scaling algorithm

compresspng.go

package main

import (
	"fmt"
	"image"
	"image/png"
	"io/ioutil"
	"os"
)

func main() {
	// Open the input file
	inFile, err := os.Open("input.png")
	if err != nil {
		fmt.Println(err)
		return
	}
	defer inFile.Close()

	// Decode the input file into an image
	img, err := png.Decode(inFile)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Scale the image to 50% of its original size
	b := img.Bounds()
	w, h := b.Max.X/2, b.Max.Y/2
	scaledImg := image.NewNRGBA(image.Rect(0, 0, w, h))
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			scaledImg.Set(x, y, img.At(x*2, y*2))
		}
	}

	// Encode the scaled image into a PNG
	buf := new(bytes.Buffer)
	err = png.Encode(buf, scaledImg)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Write the encoded image to a new file
	err = ioutil.WriteFile("output.png", buf.Bytes(), 0644)
	if err != nil {
		fmt.Println(err)
		return
	}

	fmt.Println("Image compressed successfully!")
}