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// Copyright 2019 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.
package main
import (
"flag"
"fmt"
"image"
"image/draw"
_ "image/jpeg"
"image/png"
"log"
"os"
"rescribe.xyz/preproc"
)
// 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 [-k num] [-t type] [-w num] inimg outimg\n")
flag.PrintDefaults()
}
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).")
btype := flag.String("t", "binary", "Type of threshold. binary or zeroinv are currently implemented.")
flag.Parse()
if flag.NArg() < 2 {
flag.Usage()
os.Exit(1)
}
f, err := os.Open(flag.Arg(0))
defer f.Close()
if err != nil {
log.Fatalf("Could not open file %s: %v\n", flag.Arg(0), err)
}
img, _, err := image.Decode(f)
if err != nil {
log.Fatalf("Could not decode image: %v\n", err)
}
b := img.Bounds()
gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
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
var thresh image.Image
thresh = preproc.IntegralSauvola(gray, *ksize, *wsize)
if *btype == "zeroinv" {
thresh, err = preproc.BinToZeroInv(thresh.(*image.Gray), img.(*image.RGBA))
if err != nil {
log.Fatal(err)
}
}
f, err = os.Create(flag.Arg(1))
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 {
log.Fatalf("Could not encode image: %v\n", err)
}
}
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