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-rw-r--r--preproc/cmd/cleanup/main.go62
-rw-r--r--preproc/testdata/pg1.pngbin0 -> 30803 bytes
-rw-r--r--preproc/testdata/pg1_integralwipesides_t0.02_w5.pngbin0 -> 33595 bytes
-rw-r--r--preproc/testdata/pg1_integralwipesides_t0.05_w25.pngbin0 -> 33432 bytes
-rw-r--r--preproc/testdata/pg1_integralwipesides_t0.05_w5.pngbin0 -> 14546 bytes
-rw-r--r--preproc/wipesides.go122
-rw-r--r--preproc/wipesides_test.go105
7 files changed, 289 insertions, 0 deletions
diff --git a/preproc/cmd/cleanup/main.go b/preproc/cmd/cleanup/main.go
new file mode 100644
index 0000000..7ea0c84
--- /dev/null
+++ b/preproc/cmd/cleanup/main.go
@@ -0,0 +1,62 @@
+package main
+
+// TODO: add minimum size variable (default ~30%?)
+// TODO: make into a small library
+// TODO: have the integral image specific stuff done by interface functions
+
+import (
+ "flag"
+ "fmt"
+ "image"
+ "image/draw"
+ _ "image/jpeg"
+ "image/png"
+ "log"
+ "os"
+
+ "rescribe.xyz/go.git/binarize"
+ "rescribe.xyz/go.git/preproc"
+)
+
+func main() {
+ flag.Usage = func() {
+ fmt.Fprintf(os.Stderr, "Usage: cleanup [-t thresh] [-w winsize] inimg outimg\n")
+ flag.PrintDefaults()
+ }
+ wsize := flag.Int("w", 5, "Window size for mask finding 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)
+
+ integral := binarize.Integralimg(gray)
+
+ lowedge, highedge := preproc.Findedges(integral, *wsize, *thresh)
+
+ clean := preproc.Wipesides(gray, lowedge, highedge)
+
+ 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)
+ }
+}
diff --git a/preproc/testdata/pg1.png b/preproc/testdata/pg1.png
new file mode 100644
index 0000000..c7c4249
--- /dev/null
+++ b/preproc/testdata/pg1.png
Binary files differ
diff --git a/preproc/testdata/pg1_integralwipesides_t0.02_w5.png b/preproc/testdata/pg1_integralwipesides_t0.02_w5.png
new file mode 100644
index 0000000..6b4ccb2
--- /dev/null
+++ b/preproc/testdata/pg1_integralwipesides_t0.02_w5.png
Binary files differ
diff --git a/preproc/testdata/pg1_integralwipesides_t0.05_w25.png b/preproc/testdata/pg1_integralwipesides_t0.05_w25.png
new file mode 100644
index 0000000..39dc88d
--- /dev/null
+++ b/preproc/testdata/pg1_integralwipesides_t0.05_w25.png
Binary files differ
diff --git a/preproc/testdata/pg1_integralwipesides_t0.05_w5.png b/preproc/testdata/pg1_integralwipesides_t0.05_w5.png
new file mode 100644
index 0000000..50df855
--- /dev/null
+++ b/preproc/testdata/pg1_integralwipesides_t0.05_w5.png
Binary files differ
diff --git a/preproc/wipesides.go b/preproc/wipesides.go
new file mode 100644
index 0000000..2afe1d2
--- /dev/null
+++ b/preproc/wipesides.go
@@ -0,0 +1,122 @@
+package preproc
+
+// TODO: add minimum size variable (default ~30%?)
+// TODO: have the integral image specific stuff done by interface functions
+
+import (
+ "image"
+ "image/color"
+)
+
+type windowslice struct {
+ topleft uint64
+ topright uint64
+ bottomleft uint64
+ bottomright uint64
+}
+
+func getwindowslice(i [][]uint64, x int, size int) windowslice {
+ maxy := len(i) - 1
+ maxx := x + size
+ if maxx > len(i[0])-1 {
+ maxx = len(i[0]) - 1
+ }
+
+ return windowslice{i[0][x], i[0][maxx], i[maxy][x], i[maxy][maxx]}
+}
+
+// checkwindow checks the window from x to see whether more than
+// thresh proportion of the pixels are white, if so it returns true.
+func checkwindow(integral [][]uint64, x int, size int, thresh float64) bool {
+ height := len(integral)
+ window := getwindowslice(integral, x, size)
+ // divide by 255 as each on pixel has the value of 255
+ sum := (window.bottomright + window.topleft - window.topright - window.bottomleft) / 255
+ area := size * height
+ proportion := float64(area)/float64(sum) - 1
+ return proportion <= thresh
+}
+
+// returns the proportion of the given window that is black pixels
+func proportion(integral [][]uint64, x int, size int) float64 {
+ height := len(integral)
+ window := getwindowslice(integral, x, size)
+ // divide by 255 as each on pixel has the value of 255
+ sum := (window.bottomright + window.topleft - window.topright - window.bottomleft) / 255
+ area := size * height
+ return float64(area)/float64(sum) - 1
+}
+
+// findbestedge goes through every vertical line from x to x+w to
+// find the one with the lowest proportion of black pixels.
+func findbestedge(integral [][]uint64, x int, w int) int {
+ var bestx int
+ var best float64
+
+ if w == 1 {
+ return x
+ }
+
+ right := x + w
+ for ; x < right; x++ {
+ prop := proportion(integral, x, 1)
+ if prop > best {
+ best = prop
+ bestx = x
+ }
+ }
+
+ return bestx
+}
+
+// Findedges finds the edges of the main content, by moving a window of wsize
+// from the middle of the image to the left and right, stopping when it reaches
+// a point at which there is a lower proportion of black pixels than thresh.
+func Findedges(integral [][]uint64, wsize int, thresh float64) (int, int) {
+ maxx := len(integral[0]) - 1
+ var lowedge, highedge int = 0, maxx
+
+ for x := maxx / 2; x < maxx-wsize; x++ {
+ if checkwindow(integral, x, wsize, thresh) {
+ highedge = findbestedge(integral, x, wsize)
+ break
+ }
+ }
+
+ for x := maxx / 2; x > 0; x-- {
+ if checkwindow(integral, x, wsize, thresh) {
+ lowedge = findbestedge(integral, x, wsize)
+ break
+ }
+ }
+
+ return lowedge, highedge
+}
+
+// Wipesides fills the sections of image not within the boundaries
+// of lowedge and highedge with white
+func Wipesides(img *image.Gray, lowedge int, highedge int) *image.Gray {
+ b := img.Bounds()
+ new := image.NewGray(b)
+
+ // set left edge white
+ for x := b.Min.X; x < lowedge; x++ {
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ new.SetGray(x, y, color.Gray{255})
+ }
+ }
+ // copy middle
+ for x := lowedge; x < highedge; x++ {
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ new.SetGray(x, y, img.GrayAt(x, y))
+ }
+ }
+ // set right edge white
+ for x := highedge; x < b.Max.X; x++ {
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ new.SetGray(x, y, color.Gray{255})
+ }
+ }
+
+ return new
+}
diff --git a/preproc/wipesides_test.go b/preproc/wipesides_test.go
new file mode 100644
index 0000000..76151fb
--- /dev/null
+++ b/preproc/wipesides_test.go
@@ -0,0 +1,105 @@
+package preproc
+
+// TODO: add different pages as test cases
+// TODO: test non integral img version
+
+import (
+ "flag"
+ "fmt"
+ "image"
+ "image/draw"
+ "image/png"
+ "os"
+ "testing"
+
+ "rescribe.xyz/go.git/binarize"
+)
+
+var update = flag.Bool("update", false, "update golden files")
+
+func decode(s string) (*image.Gray, error) {
+ f, err := os.Open(s)
+ defer f.Close()
+ if err != nil {
+ return nil, err
+ }
+ img, err := png.Decode(f)
+ if err != nil {
+ return nil, err
+ }
+ b := img.Bounds()
+ gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
+ draw.Draw(gray, b, img, b.Min, draw.Src)
+ return gray, nil
+}
+
+func imgsequal(img1 *image.Gray, img2 *image.Gray) bool {
+ b := img1.Bounds()
+ if !b.Eq(img2.Bounds()) {
+ return false
+ }
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ r0, g0, b0, a0 := img1.At(x, y).RGBA()
+ r1, g1, b1, a1 := img2.At(x, y).RGBA()
+ if r0 != r1 {
+ return false
+ }
+ if g0 != g1 {
+ return false
+ }
+ if b0 != b1 {
+ return false
+ }
+ if a0 != a1 {
+ return false
+ }
+ }
+ }
+ return true
+}
+
+func TestWipeSides(t *testing.T) {
+ cases := []struct {
+ name string
+ orig string
+ golden string
+ thresh float64
+ wsize int
+ }{
+ {"integralwipesides", "testdata/pg1.png", "testdata/pg1_integralwipesides_t0.02_w5.png", 0.02, 5},
+ {"integralwipesides", "testdata/pg1.png", "testdata/pg1_integralwipesides_t0.05_w5.png", 0.05, 5},
+ {"integralwipesides", "testdata/pg1.png", "testdata/pg1_integralwipesides_t0.05_w25.png", 0.05, 25},
+ }
+
+ for _, c := range cases {
+ t.Run(fmt.Sprintf("%s_%0.2f_%d", c.name, c.thresh, c.wsize), func(t *testing.T) {
+ var actual *image.Gray
+ orig, err := decode(c.orig)
+ if err != nil {
+ t.Fatalf("Could not open file %s: %v\n", c.orig, err)
+ }
+ integral := binarize.Integralimg(orig)
+ lowedge, highedge := Findedges(integral, c.wsize, c.thresh)
+ actual = Wipesides(orig, lowedge, highedge)
+ if *update {
+ f, err := os.Create(c.golden)
+ defer f.Close()
+ if err != nil {
+ t.Fatalf("Could not open file %s to update: %v\n", c.golden, err)
+ }
+ err = png.Encode(f, actual)
+ if err != nil {
+ t.Fatalf("Could not encode update of %s: %v\n", c.golden, err)
+ }
+ }
+ golden, err := decode(c.golden)
+ if err != nil {
+ t.Fatalf("Could not open file %s: %v\n", c.golden, err)
+ }
+ if !imgsequal(golden, actual) {
+ t.Errorf("Processed %s differs to %s\n", c.orig, c.golden)
+ }
+ })
+ }
+}