diff options
| -rw-r--r-- | binarize/cmd/binarize/main.go | 13 | ||||
| -rw-r--r-- | binarize/sauvola.go | 2 | ||||
| -rw-r--r-- | binarize/util.go | 20 |
3 files changed, 32 insertions, 3 deletions
diff --git a/binarize/cmd/binarize/main.go b/binarize/cmd/binarize/main.go index c4b9562..bda3d93 100644 --- a/binarize/cmd/binarize/main.go +++ b/binarize/cmd/binarize/main.go @@ -20,11 +20,12 @@ func autowsize(bounds image.Rectangle) int { func main() { flag.Usage = func() { - fmt.Fprintf(os.Stderr, "Usage: sauvola [-w num] [-k num] inimg outimg\n") + 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() @@ -55,7 +56,15 @@ func main() { // TODO: come up with a way to set a good ksize automatically - thresh := binarize.IntegralSauvola(gray, *ksize, *wsize) + 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 { diff --git a/binarize/sauvola.go b/binarize/sauvola.go index ca0acf0..ee773ba 100644 --- a/binarize/sauvola.go +++ b/binarize/sauvola.go @@ -28,7 +28,7 @@ func Sauvola(img *image.Gray, ksize float64, windowsize int) *image.Gray { } // Implements Sauvola's algorithm using Integral Images, see paper -// "Effcient Implementation of Local Adaptive Thresholding Techniques Using Integral Images" +// "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 { diff --git a/binarize/util.go b/binarize/util.go index e7fcfe4..ad641c9 100644 --- a/binarize/util.go +++ b/binarize/util.go @@ -1,6 +1,7 @@ package binarize import ( + "errors" "image" "math" ) @@ -65,3 +66,22 @@ func surrounding(img *image.Gray, x int, y int, size int) []int { } 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 +} |