Add preproc command, that binarises and preprocesses together

Surprisingly opening an image takes a significant amount of the
total processing time, so this actually saves quite a bit of time
in the grand scheme of things.

1 files changed, 85 insertions, 0 deletions

diff --git a/preproc/cmd/preproc/main.go b/preproc/cmd/preproc/main.go
new file mode 100644
index 0000000..123895f
--- /dev/null
+++ b/preproc/cmd/preproc/main.go
@@ -0,0 +1,85 @@
+package main
+
+// TODO: come up with a way to set a good ksize automatically
+// TODO: add minimum size variable (default ~30%?) for wipe
+
+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: preproc [-bt bintype] [-bw winsize] [-k num] [-t thresh] [-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.")
+	wipewsize := flag.Int("ws", 5, "Window size for wiping algorithm.")
+	thresh := flag.Float64("t", 0.05, "Threshold for 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 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)
+		}
+	}
+
+	log.Print("Wiping sides")
+	clean := preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh)
+
+	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)
+	}
+}