From d8ca7b584b693a2a61dd88767a81d99bc48aca32 Mon Sep 17 00:00:00 2001 From: Nick White Date: Fri, 15 Feb 2019 17:47:57 +0000 Subject: Separate out binarize into a package, and start adding tests for it --- binarize/integralimg.go | 2 +- binarize/main.go | 70 ---------------- binarize/sauvola.go | 2 +- binarize/sauvola_test.go | 88 +++++++++++++++++++++ binarize/testdata/pg1.png | Bin 0 -> 651071 bytes binarize/testdata/pg1_integralsauvola_k0.3_w19.png | Bin 0 -> 19456 bytes binarize/testdata/pg1_integralsauvola_k0.5_w19.png | Bin 0 -> 18241 bytes binarize/testdata/pg1_integralsauvola_k0.5_w41.png | Bin 0 -> 18260 bytes binarize/util.go | 2 +- sauvola/main.go | 69 ++++++++++++++++ 10 files changed, 160 insertions(+), 73 deletions(-) delete mode 100644 binarize/main.go create mode 100644 binarize/sauvola_test.go create mode 100644 binarize/testdata/pg1.png create mode 100644 binarize/testdata/pg1_integralsauvola_k0.3_w19.png create mode 100644 binarize/testdata/pg1_integralsauvola_k0.5_w19.png create mode 100644 binarize/testdata/pg1_integralsauvola_k0.5_w41.png create mode 100644 sauvola/main.go 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 Binary files /dev/null and b/binarize/testdata/pg1.png 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 Binary files /dev/null and b/binarize/testdata/pg1_integralsauvola_k0.3_w19.png 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 Binary files /dev/null and b/binarize/testdata/pg1_integralsauvola_k0.5_w19.png 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 Binary files /dev/null and b/binarize/testdata/pg1_integralsauvola_k0.5_w41.png 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" diff --git a/sauvola/main.go b/sauvola/main.go new file mode 100644 index 0000000..c4b9562 --- /dev/null +++ b/sauvola/main.go @@ -0,0 +1,69 @@ +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: sauvola [-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 := binarize.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) + } +} -- cgit v1.2.1-24-ge1ad