From ab773582e72bf01e1cad71431d2ddea5f216cc07 Mon Sep 17 00:00:00 2001
From: Nick White <git@njw.name>
Date: Thu, 25 Jul 2019 17:53:26 +0100
Subject: Add first draft of pipelinepreprocess - completely untested, will
 contain bugs

---
 preproc/preprocmulti.go | 93 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 preproc/preprocmulti.go

(limited to 'preproc')

diff --git a/preproc/preprocmulti.go b/preproc/preprocmulti.go
new file mode 100644
index 0000000..cd7ad34
--- /dev/null
+++ b/preproc/preprocmulti.go
@@ -0,0 +1,93 @@
+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
+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
+}
-- 
cgit v1.2.1-24-ge1ad