From 15b05839f91b29319b9d6fd475007ae3ad6224e2 Mon Sep 17 00:00:00 2001
From: Nick White <git@njw.name>
Date: Mon, 13 May 2019 21:25:56 +0100
Subject: 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.
---
preproc/cmd/preproc/main.go | 85 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 85 insertions(+)
create mode 100644 preproc/cmd/preproc/main.go
(limited to 'preproc')
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)
+ }
+}
--
cgit v1.2.1-24-ge1ad