Reorganise image manipulation to separate integral image parts

Also unify everything else under preproc/

Note that the UsefulImg interface should be used by the main
functions, to simplify things, but this hasn't been done yet.

12 files changed, 0 insertions, 443 deletions

diff --git a/binarize/cmd/binarize/main.go b/binarize/cmd/binarize/main.go
deleted file mode 100644
index bda3d93..0000000
--- a/binarize/cmd/binarize/main.go
+++ /dev/null
@@ -1,78 +0,0 @@
-package main
-
-import (
-	"flag"
-	"fmt"
-	"image"
-	"image/draw"
-	_ "image/jpeg"
-	"image/png"
-	"log"
-	"os"
-
-	"rescribe.xyz/go.git/binarize"
-)
-
-// 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: binarize [-k num] [-t type] [-w num] inimg outimg\n")
-		flag.PrintDefaults()
-	}
-	wsize := flag.Int("w", 0, "Window size for sauvola algorithm. Set automatically based on resolution if not set.")
-	ksize := flag.Float64("k", 0.5, "K for sauvola algorithm. This controls the overall threshold level. Set it lower for very light text (try 0.1 or 0.2).")
-	btype := flag.String("t", "binary", "Type of threshold. binary or zeroinv are currently implemented.")
-	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 *wsize == 0 {
-		*wsize = autowsize(b)
-		log.Printf("Set window size to %d\n", *wsize)
-	}
-
-	if *wsize % 2 == 0 {
-		*wsize++
-	}
-
-	// TODO: come up with a way to set a good ksize automatically
-
-	var thresh image.Image
-	thresh = binarize.IntegralSauvola(gray, *ksize, *wsize)
-
-	if *btype == "zeroinv" {
-		thresh, err = binarize.BinToZeroInv(thresh.(*image.Gray), img.(*image.RGBA))
-		if err != nil {
-			log.Fatal(err)
-		}
-	}
-
-	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, thresh)
-	if err != nil {
-		log.Fatalf("Could not encode image: %v\n", err)
-	}
-}
diff --git a/binarize/integralimg.go b/binarize/integralimg.go
deleted file mode 100644
index 382b495..0000000
--- a/binarize/integralimg.go
+++ /dev/null
@@ -1,116 +0,0 @@
-package binarize
-
-import (
-	"image"
-	"math"
-)
-
-type integralwindow struct {
-	topleft uint64
-	topright uint64
-	bottomleft uint64
-	bottomright uint64
-	width int
-	height int
-}
-
-func Integralimg(img *image.Gray) [][]uint64 {
-	b := img.Bounds()
-	var oldy, oldx, oldxy uint64
-	var integral [][]uint64
-	for y := b.Min.Y; y < b.Max.Y; y++ {
-		newrow := []uint64{}
-		for x := b.Min.X; x < b.Max.X; x++ {
-			oldx, oldy, oldxy = 0, 0, 0
-			if x > 0 {
-				oldx = newrow[x-1]
-			}
-			if y > 0 {
-				oldy = integral[y-1][x]
-			}
-			if x > 0 && y > 0 {
-				oldxy = integral[y-1][x-1]
-			}
-			pixel := uint64(img.GrayAt(x, y).Y)
-			i := pixel + oldx + oldy - oldxy
-			newrow = append(newrow, i)
-		}
-		integral = append(integral, newrow)
-	}
-	return integral
-}
-
-func integralimgsq(img *image.Gray) [][]uint64 {
-	b := img.Bounds()
-	var oldy, oldx, oldxy uint64
-	var integral [][]uint64
-	for y := b.Min.Y; y < b.Max.Y; y++ {
-		newrow := []uint64{}
-		for x := b.Min.X; x < b.Max.X; x++ {
-			oldx, oldy, oldxy = 0, 0, 0
-			if x > 0 {
-				oldx = newrow[x-1]
-			}
-			if y > 0 {
-				oldy = integral[y-1][x]
-			}
-			if x > 0 && y > 0 {
-				oldxy = integral[y-1][x-1]
-			}
-			pixel := uint64(img.GrayAt(x, y).Y)
-			i := pixel * pixel + oldx + oldy - oldxy
-			newrow = append(newrow, i)
-		}
-		integral = append(integral, newrow)
-	}
-	return integral
-}
-
-// this gets the values of the four corners of a window, which can
-// be used to quickly calculate the mean of the area
-func getintegralwindow(integral [][]uint64, x int, y int, size int) integralwindow {
-	step := size / 2
-
-	minx, miny := 0, 0
-	maxy := len(integral)-1
-	maxx := len(integral[0])-1
-
-	if y > (step+1) {
-		miny = y - step - 1
-	}
-	if x > (step+1) {
-		minx = x - step - 1
-	}
-
-	if maxy > (y + step) {
-		maxy = y + step
-	}
-	if maxx > (x + step) {
-		maxx = x + step
-	}
-
-	return integralwindow { integral[miny][minx], integral[miny][maxx], integral[maxy][minx], integral[maxy][maxx], maxx-minx, maxy-miny}
-}
-
-func integralmean(integral [][]uint64, x int, y int, size int) float64 {
-	i := getintegralwindow(integral, x, y, size)
-	total := float64(i.bottomright + i.topleft - i.topright - i.bottomleft)
-	sqsize := float64(i.width) * float64(i.height)
-	return total / sqsize
-}
-
-func integralmeanstddev(integral [][]uint64, integralsq [][]uint64, x int, y int, size int) (float64, float64) {
-	i := getintegralwindow(integral, x, y, size)
-	isq := getintegralwindow(integralsq, x, y, size)
-
-	var total, sqtotal, sqsize float64
-
-	sqsize = float64(i.width) * float64(i.height)
-
-	total = float64(i.bottomright + i.topleft - i.topright - i.bottomleft)
-	sqtotal = float64(isq.bottomright + isq.topleft - isq.topright - isq.bottomleft)
-
-	mean := total / sqsize
-	variance := (sqtotal / sqsize) - (mean * mean)
-	return mean, math.Sqrt(variance)
-}
diff --git a/binarize/sauvola.go b/binarize/sauvola.go
deleted file mode 100644
index 6d9c1af..0000000
--- a/binarize/sauvola.go
+++ /dev/null
@@ -1,54 +0,0 @@
-package binarize
-
-import (
-	"image"
-	"image/color"
-)
-
-// Implements Sauvola's algorithm for text binarization, see paper
-// "Adaptive document image binarization" (2000)
-func Sauvola(img *image.Gray, ksize float64, windowsize int) *image.Gray {
-	b := img.Bounds()
-	new := image.NewGray(b)
-
-	for y := b.Min.Y; y < b.Max.Y; y++ {
-		for x := b.Min.X; x < b.Max.X; x++ {
-			window := surrounding(img, x, y, windowsize)
-			m, dev := meanstddev(window)
-			threshold := m * (1 + ksize * ((dev / 128) - 1))
-			if img.GrayAt(x, y).Y < uint8(threshold) {
-				new.SetGray(x, y, color.Gray{0})
-			} else {
-				new.SetGray(x, y, color.Gray{255})
-			}
-		}
-	}
-
-	return new
-}
-
-// Implements Sauvola's algorithm using Integral Images, see paper
-// "Efficient Implementation of Local Adaptive Thresholding Techniques Using Integral Images"
-// and
-// https://stackoverflow.com/questions/13110733/computing-image-integral
-func IntegralSauvola(img *image.Gray, ksize float64, windowsize int) *image.Gray {
-	b := img.Bounds()
-	new := image.NewGray(b)
-
-	integral := Integralimg(img)
-	integralsq := integralimgsq(img)
-
-	for y := b.Min.Y; y < b.Max.Y; y++ {
-		for x := b.Min.X; x < b.Max.X; x++ {
-			m, dev := integralmeanstddev(integral, integralsq, x, y, windowsize)
-			threshold := m * (1 + ksize * ((dev / 128) - 1))
-			if img.GrayAt(x, y).Y < uint8(threshold) {
-				new.SetGray(x, y, color.Gray{0})
-			} else {
-				new.SetGray(x, y, color.Gray{255})
-			}
-		}
-	}
-
-	return new
-}
diff --git a/binarize/sauvola_test.go b/binarize/sauvola_test.go
deleted file mode 100644
index 5faeb61..0000000
--- a/binarize/sauvola_test.go
+++ /dev/null
@@ -1,108 +0,0 @@
-package binarize
-
-import (
-	"flag"
-	"fmt"
-	"image"
-	"image/draw"
-	"image/png"
-	"os"
-	"testing"
-)
-
-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 TestBinarization(t *testing.T) {
-	cases := []struct {
-		name string
-		orig string
-		golden string
-		ksize float64
-		wsize int
-	}{
-		{"integralsauvola", "testdata/pg1.png", "testdata/pg1_integralsauvola_k0.5_w41.png", 0.5, 41},
-		{"integralsauvola", "testdata/pg1.png", "testdata/pg1_integralsauvola_k0.5_w19.png", 0.5, 19},
-		{"integralsauvola", "testdata/pg1.png", "testdata/pg1_integralsauvola_k0.3_w19.png", 0.3, 19},
-		{"sauvola", "testdata/pg1.png", "testdata/pg1_sauvola_k0.5_w41.png", 0.5, 41},
-		{"sauvola", "testdata/pg1.png", "testdata/pg1_sauvola_k0.5_w19.png", 0.5, 19},
-		{"sauvola", "testdata/pg1.png", "testdata/pg1_sauvola_k0.3_w19.png", 0.3, 19},
-	}
-
-	for _, c := range cases {
-		t.Run(fmt.Sprintf("%s_%0.1f_%d", c.name, c.ksize, 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)
-			}
-			switch c.name {
-			case "integralsauvola":
-				actual = IntegralSauvola(orig, c.ksize, c.wsize)
-			case "sauvola":
-				actual = Sauvola(orig, c.ksize, c.wsize)
-			default:
-				t.Fatalf("No method %s\n", c.name)
-			}
-			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("Binarized %s differs to %s\n", c.orig, c.golden)
-			}
-		})
-	}
-}
diff --git a/binarize/testdata/pg1.png b/binarize/testdata/pg1.png
deleted file mode 100644
index 2bcc4b1..0000000
--- a/binarize/testdata/pg1.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_integralsauvola_k0.3_w19.png b/binarize/testdata/pg1_integralsauvola_k0.3_w19.png
deleted file mode 100644
index bdf5712..0000000
--- a/binarize/testdata/pg1_integralsauvola_k0.3_w19.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_integralsauvola_k0.5_w19.png b/binarize/testdata/pg1_integralsauvola_k0.5_w19.png
deleted file mode 100644
index 5db2d9a..0000000
--- a/binarize/testdata/pg1_integralsauvola_k0.5_w19.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_integralsauvola_k0.5_w41.png b/binarize/testdata/pg1_integralsauvola_k0.5_w41.png
deleted file mode 100644
index 050d037..0000000
--- a/binarize/testdata/pg1_integralsauvola_k0.5_w41.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_sauvola_k0.3_w19.png b/binarize/testdata/pg1_sauvola_k0.3_w19.png
deleted file mode 100644
index bcd595f..0000000
--- a/binarize/testdata/pg1_sauvola_k0.3_w19.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_sauvola_k0.5_w19.png b/binarize/testdata/pg1_sauvola_k0.5_w19.png
deleted file mode 100644
index 8de596c..0000000
--- a/binarize/testdata/pg1_sauvola_k0.5_w19.png
+++ /dev/null
diff --git a/binarize/testdata/pg1_sauvola_k0.5_w41.png b/binarize/testdata/pg1_sauvola_k0.5_w41.png
deleted file mode 100644
index b8f50e0..0000000
--- a/binarize/testdata/pg1_sauvola_k0.5_w41.png
+++ /dev/null
diff --git a/binarize/util.go b/binarize/util.go
deleted file mode 100644
index ad641c9..0000000
--- a/binarize/util.go
+++ /dev/null
@@ -1,87 +0,0 @@
-package binarize
-
-import (
-	"errors"
-	"image"
-	"math"
-)
-
-func mean(i []int) float64 {
-	sum := 0
-	for _, n := range i {
-		sum += n
-	}
-	return float64(sum) / float64(len(i))
-}
-
-func stddev(i []int) float64 {
-	m := mean(i)
-
-	var sum float64
-	for _, n := range i {
-		sum += (float64(n) - m) * (float64(n) - m)
-	}
-	variance := sum / float64(len(i) - 1)
-	return math.Sqrt(variance)
-}
-
-func meanstddev(i []int) (float64, float64) {
-	m := mean(i)
-
-	var sum float64
-	for _, n := range i {
-		sum += (float64(n) - m) * (float64(n) - m)
-	}
-	variance := float64(sum) / float64(len(i) - 1)
-	return m, math.Sqrt(variance)
-}
-
-// gets the pixel values surrounding a point in the image
-func surrounding(img *image.Gray, x int, y int, size int) []int {
-	b := img.Bounds()
-	step := size / 2
-
-	miny := y - step
-	if miny < b.Min.Y {
-		miny = b.Min.Y
-	}
-	minx := x - step
-	if minx < b.Min.X {
-		minx = b.Min.X
-	}
-	maxy := y + step
-	if maxy > b.Max.Y {
-		maxy = b.Max.Y
-	}
-	maxx := x + step
-	if maxx > b.Max.X {
-		maxx = b.Max.X
-	}
-
-	var s []int
-	for yi := miny; yi <= maxy; yi++ {
-		for xi := minx; xi <= maxx; xi++ {
-			s = append(s, int(img.GrayAt(xi, yi).Y))
-		}
-	}
-	return s
-}
-
-func BinToZeroInv(bin *image.Gray, orig *image.RGBA) (*image.RGBA, error) {
-	b := bin.Bounds()
-	if ! b.Eq(orig.Bounds()) {
-		return orig, errors.New("bin and orig images need to be the same dimensions")
-	}
-	newimg := image.NewRGBA(image.Rect(0, 0, b.Dx(), b.Dy()))
-	for y := b.Min.Y; y < b.Max.Y; y++ {
-		for x := b.Min.X; x < b.Max.X; x++ {
-			if bin.GrayAt(x, y).Y == 255 {
-				newimg.Set(x, y, bin.GrayAt(x, y))
-			} else {
-				newimg.Set(x, y, orig.At(x, y))
-			}
-		}
-	}
-
-	return newimg, nil
-}