summaryrefslogtreecommitdiff
path: root/binarize
diff options
context:
space:
mode:
authorNick White <git@njw.name>2019-02-15 17:47:57 +0000
committerNick White <git@njw.name>2019-02-15 17:47:57 +0000
commitd8ca7b584b693a2a61dd88767a81d99bc48aca32 (patch)
tree16b80731ccc764699e0c06e26e90a33bc651cc8d /binarize
parent3e31e5f58b89c2f71c8a306950173bab221dc565 (diff)
Separate out binarize into a package, and start adding tests for it
Diffstat (limited to 'binarize')
-rw-r--r--binarize/integralimg.go2
-rw-r--r--binarize/main.go70
-rw-r--r--binarize/sauvola.go2
-rw-r--r--binarize/sauvola_test.go88
-rw-r--r--binarize/testdata/pg1.pngbin0 -> 651071 bytes
-rw-r--r--binarize/testdata/pg1_integralsauvola_k0.3_w19.pngbin0 -> 19456 bytes
-rw-r--r--binarize/testdata/pg1_integralsauvola_k0.5_w19.pngbin0 -> 18241 bytes
-rw-r--r--binarize/testdata/pg1_integralsauvola_k0.5_w41.pngbin0 -> 18260 bytes
-rw-r--r--binarize/util.go2
9 files changed, 91 insertions, 73 deletions
diff --git a/binarize/integralimg.go b/binarize/integralimg.go
index c585d60..75e9cce 100644
--- a/binarize/integralimg.go
+++ b/binarize/integralimg.go
@@ -1,4 +1,4 @@
-package main
+package binarize
import (
"image"
diff --git a/binarize/main.go b/binarize/main.go
deleted file mode 100644
index ec99c09..0000000
--- a/binarize/main.go
+++ /dev/null
@@ -1,70 +0,0 @@
-package main
-
-// TODO: could look into other algorithms, see for examples see
-// the README at https://github.com/brandonmpetty/Doxa
-
-import (
- "flag"
- "fmt"
- "image"
- "image/draw"
- _ "image/jpeg"
- "image/png"
- "log"
- "os"
-)
-
-// 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 [-w num] [-k 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).")
- 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
-
- thresh := IntegralSauvola(gray, *ksize, *wsize)
-
- 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/sauvola.go b/binarize/sauvola.go
index bc311ad..ca0acf0 100644
--- a/binarize/sauvola.go
+++ b/binarize/sauvola.go
@@ -1,4 +1,4 @@
-package main
+package binarize
import (
"image"
diff --git a/binarize/sauvola_test.go b/binarize/sauvola_test.go
new file mode 100644
index 0000000..12a040a
--- /dev/null
+++ b/binarize/sauvola_test.go
@@ -0,0 +1,88 @@
+package binarize
+
+import (
+ "fmt"
+ "image"
+ "image/draw"
+ "image/png"
+ "os"
+ "testing"
+)
+
+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) {
+ // TODO: test non-integral sauvola method too
+ cases := []struct {
+ name string
+ orig string
+ done 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},
+ }
+
+ for _, c := range cases {
+ t.Run(fmt.Sprintf("%s_%0.1f_%d", c.name, c.ksize, c.wsize), func(t *testing.T) {
+ orig, err := decode(c.orig)
+ if err != nil {
+ t.Errorf("Could not open file %s: %v\n", c.orig, err)
+ }
+ done, err := decode(c.done)
+ if err != nil {
+ t.Errorf("Could not open file %s: %v\n", c.done, err)
+ }
+ new := IntegralSauvola(orig, c.ksize, c.wsize)
+ if ! imgsequal(done, new) {
+ t.Errorf("Binarized %s differs to %s\n", c.orig, c.done)
+ }
+ })
+ }
+}
+
+func TestIntegralImg(t *testing.T) {
+ // TODO: compare mean and stddev between integral and basic methods
+}
diff --git a/binarize/testdata/pg1.png b/binarize/testdata/pg1.png
new file mode 100644
index 0000000..2bcc4b1
--- /dev/null
+++ b/binarize/testdata/pg1.png
Binary files differ
diff --git a/binarize/testdata/pg1_integralsauvola_k0.3_w19.png b/binarize/testdata/pg1_integralsauvola_k0.3_w19.png
new file mode 100644
index 0000000..bdf5712
--- /dev/null
+++ b/binarize/testdata/pg1_integralsauvola_k0.3_w19.png
Binary files differ
diff --git a/binarize/testdata/pg1_integralsauvola_k0.5_w19.png b/binarize/testdata/pg1_integralsauvola_k0.5_w19.png
new file mode 100644
index 0000000..5db2d9a
--- /dev/null
+++ b/binarize/testdata/pg1_integralsauvola_k0.5_w19.png
Binary files differ
diff --git a/binarize/testdata/pg1_integralsauvola_k0.5_w41.png b/binarize/testdata/pg1_integralsauvola_k0.5_w41.png
new file mode 100644
index 0000000..050d037
--- /dev/null
+++ b/binarize/testdata/pg1_integralsauvola_k0.5_w41.png
Binary files differ
diff --git a/binarize/util.go b/binarize/util.go
index e7cf0f8..e7fcfe4 100644
--- a/binarize/util.go
+++ b/binarize/util.go
@@ -1,4 +1,4 @@
-package main
+package binarize
import (
"image"