Reorganise image manipulation to separate integral image parts

Also unify everything else under preproc/

Note that the UsefulImg interface should be used by the main
functions, to simplify things, but this hasn't been done yet.

1 files changed, 78 insertions, 0 deletions

diff --git a/preproc/cmd/binarize/main.go b/preproc/cmd/binarize/main.go
new file mode 100644
index 0000000..c274f9c
--- /dev/null
+++ b/preproc/cmd/binarize/main.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/draw"
+	_ "image/jpeg"
+	"image/png"
+	"log"
+	"os"
+
+	"rescribe.xyz/go.git/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)
+	}
+}