sausheong’s gists

sausheong / .go

Created December 28, 2019 12:57

photo mosaic blog 10

	// build up the tiles database
	db := cloneTilesDB()
	// source point for each tile, which starts with 0, 0 of each tile
	sp := image.Point{0, 0}

sausheong / .go

Created December 28, 2019 12:59

photo mosaic blog 11

	for y := bounds.Min.Y; y < bounds.Max.Y; y = y + tileSize {
	for x := bounds.Min.X; x < bounds.Max.X; x = x + tileSize {
	// use the top left most pixel color as the average color
	r, g, b, _ := original.At(x, y).RGBA()
	color := [3]float64{float64(r), float64(g), float64(b)}
	// get the closest tile from the tiles DB
	nearest := nearest(color, &db)
	file, err := os.Open(nearest)
	if err == nil {
	img, _, err := image.Decode(file)

sausheong / .go

Created December 28, 2019 12:59

photo mosaic blog 12

	buf1 := new(bytes.Buffer)
	jpeg.Encode(buf1, original, nil)
	originalStr := base64.StdEncoding.EncodeToString(buf1.Bytes())

	buf2 := new(bytes.Buffer)
	jpeg.Encode(buf2, newimage, nil)
	mosaic := base64.StdEncoding.EncodeToString(buf2.Bytes())
	t1 := time.Now()
	images := map[string]string{
	"original": originalStr,

sausheong / mosaic.html

Created December 28, 2019 13:00

photo mosaic blog 13

	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
	<title>Mosaic</title>
	...
	</head>
	<body>
	<div class='container'>
	<div class="col-md-6">

sausheong / .go

Created December 28, 2019 13:02

photo mosaic blog 14

	func mosaic(w http.ResponseWriter, r *http.Request) {
	t0 := time.Now()
	r.ParseMultipartForm(10485760) // max body in memory is 10MB
	file, _, _ := r.FormFile("image")
	defer file.Close()
	tileSize, _ := strconv.Atoi(r.FormValue("tile_size"))
	original, _, _ := image.Decode(file)
	bounds := original.Bounds()
	db := cloneTilesDB()

sausheong / .go

Created December 28, 2019 13:03

photo mosaic 15

	c1 := cut(original, &db, tileSize, bounds.Min.X, bounds.Min.Y, bounds.Max.X/2, bounds.Max.Y/2)
	c2 := cut(original, &db, tileSize, bounds.Max.X/2, bounds.Min.Y, bounds.Max.X, bounds.Max.Y/2)
	c3 := cut(original, &db, tileSize, bounds.Min.X, bounds.Max.Y/2, bounds.Max.X/2, bounds.Max.Y)
	c4 := cut(original, &db, tileSize, bounds.Max.X/2, bounds.Max.Y/2, bounds.Max.X, bounds.Max.Y)

sausheong / .go

Created December 28, 2019 13:03

photo mosaic 16

	func cut(original image.Image, db *map[string][3]float64, tileSize, x1, y1, x2, y2 int) <-chan image.Image {
	c := make(chan image.Image)
	sp := image.Point{0, 0}
	go func() {
	newimage := image.NewNRGBA(image.Rect(x1, y1, x2, y2))
	for y := y1; y < y2; y = y + tileSize {
	for x := x1; x < x2; x = x + tileSize {
	r, g, b, _ := original.At(x, y).RGBA()
	color := [3]float64{float64(r), float64(g), float64(b)}
	nearest := nearest(color, db)

sausheong / .go

Created December 28, 2019 13:04

photo mosaic blog 17

	func combine(r image.Rectangle, c1, c2, c3, c4 <-chan image.Image)
	<-chan string {
	c := make(chan string)
	// start a goroutine
	go func() {
	var wg sync.WaitGroup
	img:= image.NewNRGBA(r)
	copy := func(dst draw.Image, r image.Rectangle,
	src image.Image, sp image.Point) {
	draw.Draw(dst, r, src, sp, draw.Src)

sausheong / .go

Created December 28, 2019 13:05

photo mosaic blog 18

	var s1, s2, s3, s4 image.Image
	var ok1, ok2, ok3, ok4 bool
	for {
	select {
	case s1, ok1 = <-c1:
	go copy(img, s1.Bounds(), s1, image.Point{r.Min.X, r.Min.Y})
	case s2, ok2 = <-c2:
	go copy(img, s2.Bounds(), s2, image.Point{r.Max.X / 2, r.Min.Y})
	case s3, ok3 = <-c3:
	go copy(img, s3.Bounds(), s3, image.Point{r.Min.X, r.Max.Y / 2})

sausheong / .go

Created December 28, 2019 13:06

photo mosaic blog 19

	func main() {
	// this prints out the number of CPUs in my system
	fmt.Println("Number of CPUs:", runtime.NumCPU())
	runtime.GOMAXPROCS(runtime.NumCPU())
	fmt.Println("Starting mosaic server ...")
	mux := http.NewServeMux()
	files := http.FileServer(http.Dir("public"))
	mux.Handle("/static/", http.StripPrefix("/static/", files))
	mux.HandleFunc("/", upload)
	mux.HandleFunc("/mosaic", mosaic)

Chang Sau Sheong sausheong