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" ) // 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: preproc [-bt bintype] [-bw winsize] [-k num] [-m minperc] [-nowipe] [-wt wipethresh] [-ws wipesize] inimg outimg\n") fmt.Fprintf(os.Stderr, "Binarize and preprocess an image\n") flag.PrintDefaults() } binwsize := flag.Int("bw", 0, "Window size for sauvola binarization algorithm. Set automatically based on resolution if not set.") ksize := flag.Float64("k", 0.5, "K for sauvola binarization algorithm. This controls the overall threshold level. Set it lower for very light text (try 0.1 or 0.2).") 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.") thresh := flag.Float64("wt", 0.05, "Threshold for the wiping algorithm to determine the proportion of black pixels below which a window is determined to be the edge.") 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 *binwsize == 0 { *binwsize = autowsize(b) } if *binwsize%2 == 0 { *binwsize++ } log.Print("Binarising") var clean, threshimg image.Image threshimg = preproc.IntegralSauvola(gray, *ksize, *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") clean = preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh, *min) } else { clean = threshimg } 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, clean) if err != nil { log.Fatalf("Could not encode image: %v\n", err) } }