4 files changed, 27 insertions, 13 deletions
diff --git a/preproc/cmd/preproc/main.go b/preproc/cmd/preproc/main.go
index 053de8f..d8d5b66 100644
--- a/preproc/cmd/preproc/main.go
+++ b/preproc/cmd/preproc/main.go
@@ -1,7 +1,6 @@
 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"
@@ -23,13 +22,14 @@ func autowsize(bounds image.Rectangle) int {
 
 func main() {
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: preproc [-bt bintype] [-bw winsize] [-k num] [-wt wipethresh] [-ws wipesize] inimg outimg\n")
+		fmt.Fprintf(os.Stderr, "Usage: preproc [-bt bintype] [-bw winsize] [-k num] [-m minperc] [-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.")
 	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()
@@ -71,7 +71,7 @@ func main() {
 	}
 
 	log.Print("Wiping sides")
-	clean := preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh)
+	clean := preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh, *min)
 
 	f, err = os.Create(flag.Arg(1))
 	if err != nil {
diff --git a/preproc/cmd/preprocmulti/main.go b/preproc/cmd/preprocmulti/main.go
index eea7ab4..947625e 100644
--- a/preproc/cmd/preprocmulti/main.go
+++ b/preproc/cmd/preprocmulti/main.go
@@ -1,7 +1,6 @@
 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"
@@ -26,7 +25,7 @@ func main() {
 	ksizes := []float64{0.2, 0.3, 0.4, 0.5, 0.6}
 
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: preproc [-bt bintype] [-bw winsize] [-wt wipethresh] [-ws wipesize] inimg outbase\n")
+		fmt.Fprintf(os.Stderr, "Usage: preproc [-bt bintype] [-bw winsize] [-m minperc] [-wt wipethresh] [-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)
@@ -34,6 +33,7 @@ func main() {
 	}
 	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.")
 	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()
@@ -80,7 +80,7 @@ func main() {
 		}
 
 		log.Print("Wiping sides")
-		clean := preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh)
+		clean := preproc.Wipe(threshimg.(*image.Gray), *wipewsize, *thresh, *min)
 
 		savefn := fmt.Sprintf("%s_bin%0.1f.png", flag.Arg(1), k)
 		log.Printf("Saving %s\n", savefn)
diff --git a/preproc/cmd/wipe/main.go b/preproc/cmd/wipe/main.go
index e735a0a..ceff2e7 100644
--- a/preproc/cmd/wipe/main.go
+++ b/preproc/cmd/wipe/main.go
@@ -1,7 +1,5 @@
 package main
 
-// TODO: add minimum size variable (default ~30%?)
-
 import (
 	"flag"
 	"fmt"
@@ -17,12 +15,13 @@ import (
 
 func main() {
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: wipe [-t thresh] [-w winsize] inimg outimg\n")
+		fmt.Fprintf(os.Stderr, "Usage: wipe [-m minperc] [-t thresh] [-w winsize] inimg outimg\n")
 		fmt.Fprintf(os.Stderr, "Wipes the sections of an image which are outside the content area.\n")
 		flag.PrintDefaults()
 	}
-	wsize := flag.Int("w", 5, "Window size for mask finding algorithm.")
+	min := flag.Int("m", 30, "Minimum percentage of the image width for the content width calculation to be considered valid.")
 	thresh := flag.Float64("t", 0.05, "Threshold for the proportion of black pixels below which a window is determined to be the edge.")
+	wsize := flag.Int("w", 5, "Window size for mask finding algorithm.")
 	flag.Parse()
 	if flag.NArg() < 2 {
 		flag.Usage()
@@ -42,7 +41,7 @@ func main() {
 	gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
 	draw.Draw(gray, b, img, b.Min, draw.Src)
 
-	clean := preproc.Wipe(gray, *wsize, *thresh)
+	clean := preproc.Wipe(gray, *wsize, *thresh, *min)
 
 	f, err = os.Create(flag.Arg(1))
 	if err != nil {
diff --git a/preproc/wipesides.go b/preproc/wipesides.go
index 04bfa11..9b8387a 100644
--- a/preproc/wipesides.go
+++ b/preproc/wipesides.go
@@ -90,10 +90,25 @@ func wipesides(img *image.Gray, lowedge int, highedge int) *image.Gray {
 	return new
 }
 
+// toonarrow checks whether the area between lowedge and highedge is
+// less than min % of the total image width
+func toonarrow(img *image.Gray, lowedge int, highedge int, min int) bool {
+	b := img.Bounds()
+	imgw := b.Max.X - b.Min.X
+	wipew := highedge - lowedge
+	if float64(wipew) / float64(imgw) * 100 < float64(min) {
+		return true
+	}
+	return false
+}
+
 // wipe fills the sections of image which fall outside the content
-// area with white
-func Wipe(img *image.Gray, wsize int, thresh float64) *image.Gray {
+// area with white, providing the content area is above min %
+func Wipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray {
 	integral := integralimg.ToIntegralImg(img)
 	lowedge, highedge := findedges(integral, wsize, thresh)
+	if toonarrow(img, lowedge, highedge, min) {
+		return img
+	}
 	return wipesides(img, lowedge, highedge)
 }