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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/sauvola_test.go
parent3e31e5f58b89c2f71c8a306950173bab221dc565 (diff)
Separate out binarize into a package, and start adding tests for it
Diffstat (limited to 'binarize/sauvola_test.go')
-rw-r--r--binarize/sauvola_test.go88
1 files changed, 88 insertions, 0 deletions
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
+}