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 }