initial commit

img.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"image/png"
+	"log"
+	"os"
+	"strconv"
+	"time"
+)
+
+func red(p image.Image) image.Image {
+	bits := ""
+	rect := p.Bounds()
+	n := image.NewRGBA(rect)
+	for i := 0; i < rect.Max.Y; i++ {
+		for j := 0; j < rect.Max.X; j++ {
+			r, g, _, _ := p.At(j, i).RGBA()
+			if i == 310 {
+				//c, _, _, _ := p.(*image.NRGBA).At(j, i).RGBA()
+				//c := color.RGBAModel.Convert(p.At(j, i)).(color.RGBA).R
+				fmt.Fprintf(os.Stderr, "%08b %08b\n", uint8(r), uint8(g))
+				fmt.Fprintf(os.Stderr, "%d %d\n", uint8(r), uint8(g))
+				//bin := strconv.FormatUint(uint64(c.Y), 2)
+				bin := fmt.Sprintf("%08b", uint8(g))
+				bits += string(bin[len(bin)-1])
+				prntln(" 10110101010001\n", bits)
+				time.Sleep(time.Second)
+			}
+			if r != g {
+				n.Set(j, i, color.Black)
+				continue
+			}
+			n.Set(j, i, color.White)
+			// y 1648
+			// x 1538
+		}
+	}
+	prntln(bits)
+	b := bit2bytes(bits)
+	_, a := alpha(p)
+	for i := 0; i < len(a); i++ {
+		a[i] ^= b[i]
+	}
+	bits = ""
+	for _, v := range a {
+		bits += fmt.Sprintf("%08b", ^v)
+	}
+	//prntln(bits)
+	prntln(string(bit2bytes(bits)))
+	return n
+}
+
+func alpha(p image.Image) (image.Image, []byte) {
+	bits := ""
+	rect := p.Bounds()
+	n := image.NewRGBA(rect)
+	for i := 0; i < rect.Max.Y; i++ {
+		for j := 0; j < rect.Max.X; j++ {
+			_, _, _, a := p.At(j, i).RGBA()
+			if a == 65021 {
+				n.Set(j, i, color.White)
+				if i == 310 {
+					bits += "1"
+				}
+				continue
+			}
+			if a == 65278 {
+				n.Set(j, i, color.Black)
+				if i == 310 {
+					bits += "0"
+				}
+				continue
+			}
+			n.Set(j, i, color.White)
+		}
+	}
+	return n, bit2bytes(bits)
+}
+
+func prntln(v ...interface{}) {
+	fmt.Fprintln(os.Stderr, v...)
+}
+
+func bit2bytes(s string) (b []byte) {
+	for i := 0; i < len(s)-8; i += 8 {
+		n, _ := strconv.ParseUint(s[i:i+8], 2, 8)
+		b = append(b, byte(n))
+	}
+	return
+}
+
+func main() {
+	f, err := os.Open("challenge.png")
+	if err != nil {
+		log.Fatal(err)
+	}
+	p, err := png.Decode(f)
+	if err != nil {
+		log.Fatal(err)
+	}
+	n := red(p)
+	//n, bits := alpha(p)
+	//prntln(string(bits))
+
+	err = png.Encode(os.Stdout, n)
+	if err != nil {
+		log.Fatal(err)
+	}
+}