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authorNick White <git@njw.name>2019-01-30 21:22:32 +0000
committerNick White <git@njw.name>2019-01-30 21:22:32 +0000
commit3e31e5f58b89c2f71c8a306950173bab221dc565 (patch)
tree6acd12cf9793b0eaffff4f2038ef3b51b1623502 /binarize
parent5a89da512da641732d05d5bb2c49f813672a6990 (diff)
Set window size automatically based on resolution
Diffstat (limited to 'binarize')
-rw-r--r--binarize/main.go35
1 files changed, 23 insertions, 12 deletions
diff --git a/binarize/main.go b/binarize/main.go
index aa8d4ee..ec99c09 100644
--- a/binarize/main.go
+++ b/binarize/main.go
@@ -14,23 +14,24 @@ import (
"os"
)
+// TODO: do more testing to see how good this assumption is
+func autowsize(bounds image.Rectangle) int {
+ return bounds.Dx() / 60
+}
+
func main() {
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage: binarize [-w num] [-k num] inimg outimg\n")
flag.PrintDefaults()
}
- wsize := flag.Int("w", 31, "Window size for sauvola algorithm (needs to be odd)")
- ksize := flag.Float64("k", 0.5, "K for sauvola algorithm")
+ wsize := flag.Int("w", 0, "Window size for sauvola algorithm. Set automatically based on resolution if not set.")
+ ksize := flag.Float64("k", 0.5, "K for sauvola algorithm. This controls the overall threshold level. Set it lower for very light text (try 0.1 or 0.2).")
flag.Parse()
if flag.NArg() < 2 {
flag.Usage()
os.Exit(1)
}
- if *wsize % 2 == 0 {
- *wsize++
- }
-
f, err := os.Open(flag.Arg(0))
defer f.Close()
if err != nil {
@@ -42,18 +43,28 @@ func main() {
}
b := img.Bounds()
gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
- draw.Draw(gray, b, img, b.Min, draw.Src)
+ draw.Draw(gray, b, img, b.Min, draw.Src)
+
+ if *wsize == 0 {
+ *wsize = autowsize(b)
+ log.Printf("Set window size to %d\n", *wsize)
+ }
+
+ if *wsize % 2 == 0 {
+ *wsize++
+ }
+
+ // TODO: come up with a way to set a good ksize automatically
- // TODO: estimate an appropriate window size based on resolution
thresh := IntegralSauvola(gray, *ksize, *wsize)
f, err = os.Create(flag.Arg(1))
- if err != nil {
+ if err != nil {
log.Fatalf("Could not create file %s: %v\n", flag.Arg(1), err)
- }
+ }
defer f.Close()
err = png.Encode(f, thresh)
- if err != nil {
+ if err != nil {
log.Fatalf("Could not encode image: %v\n", err)
- }
+ }
}