diff options
Diffstat (limited to 'sauvola.go')
| -rw-r--r-- | sauvola.go | 36 |
1 files changed, 15 insertions, 21 deletions
@@ -41,38 +41,32 @@ func Sauvola(img image.Image, ksize float64, windowsize int) *image.Gray { // "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 { +func IntegralSauvola(img image.Image, ksize float64, windowsize int) *image.Gray { b := img.Bounds() - new := image.NewGray(b) - - integrals := integralimg.ToAllIntegralImg(img) - for y := b.Min.Y; y < b.Max.Y; y++ { - for x := b.Min.X; x < b.Max.X; x++ { - m, dev := integrals.MeanStdDevWindow(x, y, windowsize) - threshold := m * (1 + ksize*((dev/128)-1)) - if img.GrayAt(x, y).Y < uint8(threshold) { - new.SetGray(x, y, color.Gray{0}) - } else { - new.SetGray(x, y, color.Gray{255}) - } - } - } + intImg := integralimg.NewImage(b) + draw.Draw(intImg, b, img, b.Min, draw.Src) + intSqImg := integralimg.NewSqImage(b) + draw.Draw(intSqImg, b, img, b.Min, draw.Src) - return new + return PreCalcedSauvola(*intImg, *intSqImg, img, ksize, windowsize) } // PreCalcedSauvola Implements Sauvola's algorithm using precalculated Integral Images -func PreCalcedSauvola(integrals integralimg.WithSq, img *image.Gray, ksize float64, windowsize int) *image.Gray { - // TODO: have this be the root function that the other two reference +func PreCalcedSauvola(intImg integralimg.Image, intSqImg integralimg.SqImage, img image.Image, ksize float64, windowsize int) *image.Gray { b := img.Bounds() + gray := image.NewGray(b) + draw.Draw(gray, b, img, b.Min, draw.Src) new := image.NewGray(b) for y := b.Min.Y; y < b.Max.Y; y++ { for x := b.Min.X; x < b.Max.X; x++ { - m, dev := integrals.MeanStdDevWindow(x, y, windowsize) - threshold := m * (1 + ksize*((dev/128)-1)) - if img.GrayAt(x, y).Y < uint8(threshold) { + m, dev := integralimg.MeanStdDevWindow(intImg, intSqImg, x, y, windowsize) + // Divide by 255 to adjust from Gray16 used by integralimg to 8 bit Gray + m8 := m / 255 + dev8 := dev / 255 + threshold := m8 * (1 + ksize*((dev8/128)-1)) + if gray.GrayAt(x, y).Y < uint8(math.Round(threshold)) { new.SetGray(x, y, color.Gray{0}) } else { new.SetGray(x, y, color.Gray{255}) |