// TestMean tests the mean quantizer on png files found in the source
// directory. Output files are prefixed with _mean_. Files begining with
// _ are skipped when scanning for input files. Note nothing is tested
// with a fresh source tree--drop a png or two in the source directory
// before testing to give the test something to work on. Png files in the
// parent directory are similarly used for testing. Put files there
// to compare results of the different quantizers.
func TestMean(t *testing.T) {
for _, p := range glob(t) {
f, err := os.Open(p)
if err != nil {
t.Log(err) // skip files that can't be opened
continue
}
img, err := png.Decode(f)
f.Close()
if err != nil {
t.Log(err) // skip files that can't be decoded
continue
}
pDir, pFile := filepath.Split(p)
for _, n := range []int{16, 256} {
// prefix _ on file name marks this as a result
fq, err := os.Create(fmt.Sprintf("%s_mean_%d_%s", pDir, n, pFile))
if err != nil {
t.Fatal(err) // probably can't create any others
}
var q quant.Quantizer = mean.Quantizer(n)
if err = png.Encode(fq, q.Image(img)); err != nil {
t.Fatal(err) // any problem is probably a problem for all
}
}
}
}
func main() {
mode := flag.String("mode", "median", "'median' or 'mean' (default 'median')")
size := flag.Int("size", 16, "Palette size (default 16)")
flag.Parse()
paths := flag.Args()
if len(paths) == 0 {
log.Fatal("No images specified")
}
var wg sync.WaitGroup
wg.Add(len(paths))
for _, path := range paths {
go func(path string) {
defer wg.Done()
var buff bytes.Buffer
buff.WriteString(fmt.Sprintf("\n%s\n", path))
reader, err := os.Open(path)
if err != nil {
log.Fatal(err)
}
defer reader.Close()
img, _, err := image.Decode(reader)
if err != nil {
log.Fatal(err)
}
var q quant.Quantizer
if *mode == "median" {
q = median.Quantizer(*size)
} else {
q = mean.Quantizer(*size)
}
pal := q.Palette(img)
for _, c := range pal.ColorPalette() {
r, g, b, _ := c.RGBA()
buff.WriteString(fmt.Sprintf("#%02x%02x%02x\n", uint8(r>>8), uint8(g>>8), uint8(b>>8)))
}
fmt.Print(buff.String())
}(path)
}
wg.Wait()
}
func BenchmarkPalette(b *testing.B) {
var img image.Image
for _, p := range glob(b) {
f, err := os.Open(p)
if err != nil {
b.Log(err) // skip files that can't be opened
continue
}
img, err = png.Decode(f)
f.Close()
if err != nil {
b.Log(err) // skip files that can't be decoded
continue
}
break
}
var q quant.Quantizer = mean.Quantizer(256)
b.ResetTimer()
for i := 0; i < b.N; i++ {
q.Palette(img)
}
}