From 60071c2ea95e284f6c765528e81b930fe3fb4b92 Mon Sep 17 00:00:00 2001
From: Nick White <git@njw.name>
Date: Tue, 3 Mar 2020 18:18:36 +0000
Subject: Add experimental vertical wiping feature to wiper

---
 cmd/wipe/main.go | 14 +++++++++-----
 wipesides.go     | 26 ++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/cmd/wipe/main.go b/cmd/wipe/main.go
index d4c95ac..beeced2 100644
--- a/cmd/wipe/main.go
+++ b/cmd/wipe/main.go
@@ -19,13 +19,16 @@ import (
 
 func main() {
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: wipe [-m minperc] [-t thresh] [-w winsize] inimg outimg\n")
+		fmt.Fprintf(os.Stderr, "Usage: wipe inimg outimg\n")
 		fmt.Fprintf(os.Stderr, "Wipes the sections of an image which are outside the content area.\n")
 		flag.PrintDefaults()
 	}
-	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. Higher means more aggressive wiping.")
-	wsize := flag.Int("w", 5, "Window size for mask finding algorithm.")
+	min := flag.Int("hm", 30, "Minimum percentage of the image width for the content width calculation to be considered valid.")
+	thresh := flag.Float64("ht", 0.05, "Threshold for the proportion of black pixels below which a window is determined to be the edge. Higher means more aggressive wiping.")
+	wsize := flag.Int("hw", 5, "Window size for mask finding algorithm.")
+	vmin := flag.Int("vm", 30, "Minimum percentage of the image height for the content width calculation to be considered valid.")
+	vthresh := flag.Float64("vt", 0.005, "Threshold for the proportion of black pixels below which a vertical wipe window is determined to be the edge. Higher means more aggressive wiping.")
+	vwsize := flag.Int("vw", 120, "Window size for vertical mask finding algorithm. Should be set to approximately line height + largest expected gap.")
 	flag.Parse()
 	if flag.NArg() < 2 {
 		flag.Usage()
@@ -45,7 +48,8 @@ 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, *min)
+	sidesdone := preproc.Wipe(gray, *wsize, *thresh, *min)
+	clean := preproc.VWipe(sidesdone, *vwsize, *vthresh, *vmin)
 
 	f, err = os.Create(flag.Arg(1))
 	if err != nil {
diff --git a/wipesides.go b/wipesides.go
index 3bedf67..0fc4a32 100644
--- a/wipesides.go
+++ b/wipesides.go
@@ -116,6 +116,19 @@ func toonarrow(img *image.Gray, lowedge int, highedge int, min int) bool {
 	return false
 }
 
+// func sideways flips an image by sideways
+func sideways(img *image.Gray) *image.Gray {
+	b := img.Bounds()
+	newb := image.Rect(b.Min.Y, b.Min.X, b.Max.Y, b.Max.X)
+	new := image.NewGray(newb)
+	for x := b.Min.X; x < b.Max.X; x++ {
+		for y := b.Min.Y; y < b.Max.Y; y++ {
+			new.SetGray(y, x, img.GrayAt(x, y))
+		}
+	}
+	return new
+}
+
 // Wipe fills the sections of image which fall outside the content
 // area with white, providing the content area is above min %
 func Wipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray {
@@ -127,6 +140,19 @@ func Wipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray {
 	return wipesides(img, lowedge, highedge)
 }
 
+// VWipe fills the sections of image which fall outside the vertical
+// content area with white, providing the content area is above min %
+func VWipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray {
+	rotimg := sideways(img)
+	integral := integralimg.ToIntegralImg(rotimg)
+	lowedge, highedge := findedges(integral, wsize, thresh)
+	if toonarrow(img, lowedge, highedge, min) {
+		return img
+	}
+	wiped := wipesides(rotimg, lowedge, highedge)
+	return sideways(wiped)
+}
+
 // WipeFile wipes an image file, filling the sections of the image
 // which fall outside the content area with white, providing the
 // content area is above min %.
-- 
cgit v1.2.1-24-ge1ad