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authorNick White <git@njw.name>2020-02-13 09:04:38 +0000
committerNick White <git@njw.name>2020-02-13 09:04:38 +0000
commit699634be83582c47075db8520ab262669990a325 (patch)
tree27770493494ca9b0258a06e72431fd46b6c7a50f /cmd/splittable
parent787d63fc5d13c6250bd33da5a8e1eadbe86188cd (diff)
Add experimental and partial splittable tool
Diffstat (limited to 'cmd/splittable')
-rw-r--r--cmd/splittable/main.go139
1 files changed, 139 insertions, 0 deletions
diff --git a/cmd/splittable/main.go b/cmd/splittable/main.go
new file mode 100644
index 0000000..1029db1
--- /dev/null
+++ b/cmd/splittable/main.go
@@ -0,0 +1,139 @@
+package main
+
+import (
+ "flag"
+ "fmt"
+ "image"
+ "image/draw"
+ _ "image/jpeg"
+ "image/png"
+ "log"
+ "os"
+
+ "rescribe.xyz/preproc/integralimg"
+)
+
+const usage = `Usage: splittable [-t thresh] [-w winsize] inimg outbase
+
+splittable is an experimental program to split a table into individual
+cells suitable for OCR. It does this by detecting lines. At present it
+just detects vertical lines and outputs images for each section
+between those lines.
+
+`
+
+// returns the proportion of the given window that is black pixels
+func proportion(i integralimg.I, x int, size int) float64 {
+ w := i.GetVerticalWindow(x, size)
+ return w.Proportion()
+}
+
+// findbestvline goes through every vertical line from x to x+w to
+// find the one with the lowest proportion of black pixels.
+func findbestvline(img integralimg.I, x int, w int) int {
+ var bestx int
+ var best float64
+
+ if w == 1 {
+ return x
+ }
+
+ right := x + w
+ for ; x < right; x++ {
+ prop := proportion(img, x, 1)
+ if prop > best {
+ best = prop
+ bestx = x
+ }
+ }
+
+ return bestx
+}
+
+// findvlines finds vertical lines, returning an array of x coordinates
+// for each line. It works by moving a window of wsize across the image,
+// marking each place where there is a higher proportion of black pixels
+// than thresh.
+func findvlines(img integralimg.I, wsize int, thresh float64) []int {
+ maxx := len(img[0]) - 1
+ var lines []int
+
+ for x := 0; x < maxx-wsize; x+=wsize {
+ if proportion(img, x, wsize) >= thresh {
+ l := findbestvline(img, x, wsize)
+ lines = append(lines, l)
+ }
+ }
+
+ return lines
+}
+
+func drawsection(img *image.Gray, x1 int, x2 int) *image.Gray {
+ b := img.Bounds()
+ width := x2-x1
+ new := image.NewGray(image.Rect(0, b.Min.Y, width, b.Max.Y))
+
+ for x := 0; x < width; x++ {
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ new.SetGray(x, y, img.GrayAt(x1 + x, y))
+ }
+ }
+
+ return new
+}
+
+func main() {
+ flag.Usage = func() {
+ fmt.Fprintf(flag.CommandLine.Output(), usage)
+ flag.PrintDefaults()
+ }
+ thresh := flag.Float64("t", 0.85, "Threshold for the proportion of black pixels below which a window is determined to be a line. Higher means fewer lines will be found.")
+ wsize := flag.Int("w", 1, "Window size for mask finding algorithm.")
+ flag.Parse()
+ if flag.NArg() < 2 {
+ flag.Usage()
+ os.Exit(1)
+ }
+
+ f, err := os.Open(flag.Arg(0))
+ defer f.Close()
+ if err != nil {
+ log.Fatalf("Could not open file %s: %v\n", flag.Arg(0), err)
+ }
+ img, _, err := image.Decode(f)
+ if err != nil {
+ log.Fatalf("Could not decode image: %v\n", err)
+ }
+ b := img.Bounds()
+ gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy()))
+ draw.Draw(gray, b, img, b.Min, draw.Src)
+
+ integral := integralimg.ToIntegralImg(gray)
+ vlines := findvlines(integral, *wsize, *thresh)
+
+ for i, v := range vlines {
+ fmt.Printf("line detected at x=%d\n", v)
+
+ if i+1 >= len(vlines) {
+ break
+ }
+ section := drawsection(gray, v, vlines[i+1])
+
+ fn := fmt.Sprintf("%s-%d.png", flag.Arg(1), v)
+ f, err = os.Create(fn)
+ if err != nil {
+ log.Fatalf("Could not create file %s: %v\n", fn, err)
+ }
+ defer f.Close()
+ err := png.Encode(f, section)
+ if err != nil {
+ log.Fatalf("Could not encode image %s: %v\n", fn, err)
+ }
+ }
+
+
+ // TODO: find horizontal lines too
+ // TODO: do rotation
+ // TODO: output table cells
+ // TODO: potentially send cells straight to tesseract
+}