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/go.git/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 }