diff --git a/20/main.go b/20/main.go
new file mode 100644
index 0000000..183f83a
--- /dev/null
+++ b/20/main.go
@@ -0,0 +1,165 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+func main() {
+	start := time.Now()
+	partOne()
+	duration := time.Since(start)
+	partTwo()
+	duration2 := time.Since(start)
+	fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
+}
+
+func makeScanner(test bool) *bufio.Scanner {
+	var f *os.File
+	if test {
+		f, _ = os.Open("inputs/testinput")
+	} else {
+		f, _ = os.Open("inputs/input")
+	}
+	reader := bufio.NewReader(f)
+	return bufio.NewScanner(reader)
+}
+
+type coord struct {
+	x int
+	y int
+}
+
+// grid SHOULD be like this:
+//   x ->
+// y
+// |
+// V
+
+type image struct {
+	background rune // what all uninitialized cells are set to; defaults to '.'
+	grid       map[coord]rune
+	topleft    coord
+	size       int
+}
+
+func GetNeighbors(c coord) []coord {
+	return []coord{
+		{x: c.x - 1, y: c.y - 1},
+		{x: c.x, y: c.y - 1},
+		{x: c.x + 1, y: c.y - 1},
+
+		{x: c.x - 1, y: c.y},
+		{x: c.x, y: c.y},
+		{x: c.x + 1, y: c.y},
+
+		{x: c.x - 1, y: c.y + 1},
+		{x: c.x, y: c.y + 1},
+		{x: c.x + 1, y: c.y + 1},
+	}
+}
+
+func (img *image) GetNewRune(coord coord, enhancementMap string) rune {
+	index := 0
+	coords := GetNeighbors(coord)
+	for i := 0; i < len(coords); i++ {
+		value := img.grid[coords[i]]
+		if value == 0 {
+			value = img.background
+		}
+		if value == '#' {
+			index += (1 << (8 - i))
+		}
+	}
+	return rune(enhancementMap[index])
+}
+
+func (img *image) CountBrightPixels() int {
+	count := 0
+	for _, v := range img.grid {
+		if v == '#' {
+			count++
+		}
+	}
+	return count
+}
+
+func (img *image) Print() {
+	fmt.Println(strings.Repeat(string(img.background), img.size+2))
+	for y := img.topleft.y; y < img.size+img.topleft.y; y++ {
+		fmt.Print(string(img.background))
+		for x := img.topleft.x; x < img.size+img.topleft.x; x++ {
+			fmt.Printf("%s", string(img.grid[coord{x, y}]))
+		}
+		fmt.Printf("%s\n", string(img.background))
+	}
+	fmt.Println(strings.Repeat(string(img.background), img.size+2))
+}
+
+func Enhance(img *image, m string) *image {
+	next := &image{
+		topleft: coord{
+			x: img.topleft.x - 1,
+			y: img.topleft.y - 1,
+		},
+		size: img.size + 2,
+		grid: map[coord]rune{},
+	}
+	if img.background == '.' { // permute new "background" value
+		next.background = rune(m[0])
+	} else if img.background == '#' {
+		next.background = rune(m[511])
+	}
+	for y := img.topleft.y - 1; y < img.size+1; y++ {
+		for x := img.topleft.x - 1; x < img.size+1; x++ {
+			next.grid[coord{x, y}] = img.GetNewRune(coord{x, y}, m)
+		}
+	}
+	return next
+}
+
+func partOne() {
+	scanner := makeScanner(false)
+
+	scanner.Scan()
+	enhancementString := scanner.Text()
+	scanner.Scan() // eat empty line
+
+	img := &image{
+		background: '.',
+		grid:       map[coord]rune{},
+		topleft:    coord{0, 0},
+	}
+
+	y := 0
+	for scanner.Scan() {
+		line := scanner.Text()
+		img.size = len(line)
+		for x, c := range line {
+			img.grid[coord{x, y}] = c
+		}
+		y++
+	}
+
+	img.Print()
+	fmt.Println(img.CountBrightPixels())
+	fmt.Println("")
+
+	for i := 0; i < 2; i++ {
+		img = Enhance(img, enhancementString)
+		img.Print()
+		fmt.Println(img.CountBrightPixels())
+		fmt.Println("")
+	}
+}
+
+func partTwo() {
+	scanner := makeScanner(false)
+
+	for scanner.Scan() {
+		// line := scanner.Text()
+	}
+}
diff --git a/20/main_test.go b/20/main_test.go
new file mode 100644
index 0000000..69792f8
--- /dev/null
+++ b/20/main_test.go
@@ -0,0 +1,66 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGetNewRune(t *testing.T) {
+	img := image{
+		grid: map[coord]rune{
+			{0, 0}: '.', {1, 0}: '.', {2, 0}: '.',
+			{0, 1}: '.', {1, 1}: '.', {2, 1}: '.',
+			{0, 2}: '.', {1, 2}: '.', {2, 2}: '.',
+		},
+	}
+	if img.GetNewRune(coord{1, 1}, ".") != '.' {
+		t.Fail()
+	}
+
+	img = image{
+		grid: map[coord]rune{
+			{0, 0}: '.', {1, 0}: '.', {2, 0}: '.',
+			{0, 1}: '.', {1, 1}: '.', {2, 1}: '.',
+			{0, 2}: '.', {1, 2}: '.', {2, 2}: '#',
+		},
+	}
+	if img.GetNewRune(coord{1, 1}, ".#") != '#' {
+		t.Fail()
+	}
+
+	img = image{
+		grid: map[coord]rune{
+			{0, 0}: '.', {1, 0}: '.', {2, 0}: '.',
+			{0, 1}: '.', {1, 1}: '.', {2, 1}: '.',
+			{0, 2}: '.', {1, 2}: '#', {2, 2}: '.',
+		},
+	}
+	if img.GetNewRune(coord{1, 1}, "..#.") != '#' {
+		t.Fail()
+	}
+
+	img = image{
+		grid: map[coord]rune{
+			{0, 0}: '.', {1, 0}: '.', {2, 0}: '.',
+			{0, 1}: '.', {1, 1}: '.', {2, 1}: '.',
+			{0, 2}: '.', {1, 2}: '#', {2, 2}: '#',
+		},
+	}
+	if img.GetNewRune(coord{1, 1}, "...#") != '#' {
+		t.Fail()
+	}
+
+	img = image{
+		background: '#',
+		grid: map[coord]rune{
+			{0, 0}: '.', {1, 0}: '.', {2, 0}: '.',
+			{0, 1}: '.', {1, 1}: '.', {2, 1}: '.',
+			{0, 2}: '.', {1, 2}: '#', {2, 2}: '#',
+		},
+	}
+	m := strings.Repeat(".", 484)
+	m += "#"
+	if img.GetNewRune(coord{0, 0}, m) != '#' { // 111100100, or 484
+		t.Fail()
+	}
+}