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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.
// preprocmulti runs binarisation with a variety of different binarisation
// levels, preprocessing and saving each version
package main
// TODO: come up with a way to set a good ksize automatically
import (
"flag"
"fmt"
"image"
"image/draw"
_ "image/jpeg"
"image/png"
"log"
"os"
"rescribe.xyz/preproc"
"rescribe.xyz/integral"
)
// TODO: do more testing to see how good this assumption is
func autowsize(bounds image.Rectangle) int {
return bounds.Dx() / 60
}
func main() {
ksizes := []float64{0.1, 0.2, 0.4, 0.5}
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage: preprocmulti [-bt bintype] [-bw winsize] [-m minperc] [-nowipe] [-ws wipesize] inimg outbase\n")
fmt.Fprintf(os.Stderr, "Binarize and preprocess an image, with multiple binarisation levels,\n")
fmt.Fprintf(os.Stderr, "saving images to outbase_bin{k}.png.\n")
fmt.Fprintf(os.Stderr, "Binarises with these levels for k: %v.\n", ksizes)
flag.PrintDefaults()
}
binwsize := flag.Int("bw", 0, "Window size for sauvola binarization algorithm. Set automatically based on resolution if not set.")
btype := flag.String("bt", "binary", "Type of binarization threshold. binary or zeroinv are currently implemented.")
min := flag.Int("m", 30, "Minimum percentage of the image width for the content width calculation to be considered valid.")
nowipe := flag.Bool("nowipe", false, "Disable wiping completely.")
wipewsize := flag.Int("ws", 5, "Window size for wiping algorithm.")
vmin := flag.Int("vm", 30, "Minimum percentage of the image height for the content width calculation to be considered valid.")
vthresh := flag.Float64("vt", 0.005, "Threshold for the proportion of black pixels below which a vertical wipe window is determined to be the edge. Higher means more aggressive wiping.")
vwsize := flag.Int("vw", 120, "Window size for vertical mask finding algorithm. Should be set to approximately line height + largest expected gap.")
flag.Parse()
if flag.NArg() < 2 {
flag.Usage()
os.Exit(1)
}
log.Printf("Opening %s\n", flag.Arg(0))
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()
if *binwsize == 0 {
*binwsize = autowsize(b)
}
if *binwsize%2 == 0 {
*binwsize++
}
var clean, threshimg, vclean image.Image
log.Print("Precalculating integral images")
intImg := integral.NewImage(b)
draw.Draw(intImg, b, img, b.Min, draw.Src)
intSqImg := integral.NewSqImage(b)
draw.Draw(intSqImg, b, img, b.Min, draw.Src)
for _, k := range ksizes {
log.Print("Binarising")
threshimg = preproc.PreCalcedSauvola(*intImg, *intSqImg, img, k, *binwsize)
if *btype == "zeroinv" {
threshimg, err = preproc.BinToZeroInv(threshimg.(*image.Gray), img.(*image.RGBA))
if err != nil {
log.Fatal(err)
}
}
if !*nowipe {
log.Print("Wiping sides")
vclean = preproc.VWipe(threshimg.(*image.Gray), *vwsize, *vthresh, *vmin)
clean = preproc.Wipe(vclean.(*image.Gray), *wipewsize, k*0.02, *min)
} else {
clean = threshimg
}
savefn := fmt.Sprintf("%s_bin%0.1f.png", flag.Arg(1), k)
log.Printf("Saving %s\n", savefn)
f, err = os.Create(savefn)
if err != nil {
log.Fatalf("Could not create file %s: %v\n", savefn, err)
}
defer f.Close()
err = png.Encode(f, clean)
if err != nil {
log.Fatalf("Could not encode image: %v\n", err)
}
}
}
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