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// Copyright 2019 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.
package preproc
// TODO: come up with a way to set a good ksize automatically
import (
"fmt"
"image"
"image/draw"
_ "image/jpeg"
"image/png"
"os"
"strings"
"rescribe.xyz/preproc/integralimg"
)
// TODO: do more testing to see how good this assumption is
func autowsize(bounds image.Rectangle) int {
return bounds.Dx() / 60
}
// PreProcMulti binarizes and preprocesses an image with multiple binarisation levels.
// inPath: Path of input image.
// ksizes: Slice of k values to pass to Sauvola algorithm
// binType: Type of binarization threshold. binary or zeroinv are currently implemented.
// binWsize: Window size for sauvola binarization algorithm. Set automatically based on resolution if 0.
// wipe: Whether to wipe (clear sides) the image
// wipeWsize: Window size for wiping algorithm
// wipeMinWidthPerc: Minimum percentage of the image width for the content width calculation to be considered valid
// Note: copied from cmd/preprocmulti/main.go, should think about the best way
// to organise this code later.
// TODO: return errors that encapsulate the err describing where it was encountered
// TODO: do the post-integral image stuff in separate goroutines for speed
func PreProcMulti(inPath string, ksizes []float64, binType string, binWsize int, wipe bool, wipeWsize int, wipeMinWidthPerc int) ([]string, error) {
// Make outBase inPath up to final .
s := strings.Split(inPath, ".")
outBase := strings.Join(s[:len(s)-1], "")
var donePaths []string
f, err := os.Open(inPath)
if err != nil {
return donePaths, err
}
defer f.Close()
img, _, err := image.Decode(f)
if err != nil {
return donePaths, 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 binWsize == 0 {
binWsize = autowsize(b)
}
if binWsize%2 == 0 {
binWsize++
}
var clean, threshimg image.Image
integrals := integralimg.ToAllIntegralImg(gray)
for _, k := range ksizes {
threshimg = PreCalcedSauvola(integrals, gray, k, binWsize)
if binType == "zeroinv" {
threshimg, err = BinToZeroInv(threshimg.(*image.Gray), img.(*image.RGBA))
if err != nil {
return donePaths, err
}
}
if wipe {
clean = Wipe(threshimg.(*image.Gray), wipeWsize, k*0.02, wipeMinWidthPerc)
} else {
clean = threshimg
}
savefn := fmt.Sprintf("%s_bin%0.1f.png", outBase, k)
f, err = os.Create(savefn)
if err != nil {
return donePaths, err
}
defer f.Close()
err = png.Encode(f, clean)
if err != nil {
return donePaths, err
}
donePaths = append(donePaths, savefn)
}
return donePaths, nil
}
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