package main import ( "flag" "fmt" "image" "image/color" "image/draw" _ "image/jpeg" "image/png" "log" "os" "rescribe.xyz/go.git/binarize" ) type windowslice struct { topleft uint64 topright uint64 bottomleft uint64 bottomright uint64 } func getwindowslice(i [][]uint64, x int, size int) windowslice { maxy := len(i) - 1 maxx := x + size if maxx > len(i[0])-1 { maxx = len(i[0]) - 1 } return windowslice{i[0][x], i[0][maxx], i[maxy][x], i[maxy][maxx]} } // checkwindow checks the window from x to see whether more than // thresh proportion of the pixels are white, if so it returns true. func checkwindow(integral [][]uint64, x int, size int, thresh float64) bool { height := len(integral) window := getwindowslice(integral, x, size) // divide by 255 as each on pixel has the value of 255 sum := (window.bottomright + window.topleft - window.topright - window.bottomleft) / 255 area := size * height proportion := float64(area)/float64(sum) - 1 return proportion <= thresh } // cleanimg fills the sections of image not within the boundaries // of lowedge and highedge with white func cleanimg(img *image.Gray, lowedge int, highedge int) *image.Gray { b := img.Bounds() new := image.NewGray(b) // set left edge white for x := b.Min.X; x < lowedge; x++ { for y := b.Min.Y; y < b.Max.Y; y++ { new.SetGray(x, y, color.Gray{255}) } } // copy middle for x := lowedge; x < highedge; x++ { for y := b.Min.Y; y < b.Max.Y; y++ { new.SetGray(x, y, img.GrayAt(x, y)) } } // set right edge white for x := highedge; x < b.Max.X; x++ { for y := b.Min.Y; y < b.Max.Y; y++ { new.SetGray(x, y, color.Gray{255}) } } return new } // findedges finds the edges of the main content, by moving a window of wsize // from the middle of the image to the left and right, stopping when it reaches // a point at which there is a lower proportion of black pixels than thresh. func findedges(integral [][]uint64, wsize int, thresh float64) (int, int) { maxx := len(integral[0]) - 1 var lowedge, highedge int = 0, maxx for x := maxx / 2; x < maxx-wsize; x++ { if checkwindow(integral, x, wsize, thresh) { highedge = x + (wsize / 2) break } } for x := maxx / 2; x > 0; x-- { if checkwindow(integral, x, wsize, thresh) { lowedge = x - (wsize / 2) break } } return lowedge, highedge } func main() { flag.Usage = func() { fmt.Fprintf(os.Stderr, "Usage: cleanup [-t thresh] [-w winsize] inimg outimg\n") flag.PrintDefaults() } wsize := flag.Int("w", 5, "Window size for mask finding algorithm.") thresh := flag.Float64("t", 0.05, "Threshold for the proportion of black pixels below which a window is determined to be the edge.") 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 := binarize.Integralimg(gray) lowedge, highedge := findedges(integral, *wsize, *thresh) clean := cleanimg(gray, lowedge, highedge) f, err = os.Create(flag.Arg(1)) if err != nil { log.Fatalf("Could not create file %s: %v\n", flag.Arg(1), err) } defer f.Close() err = png.Encode(f, clean) if err != nil { log.Fatalf("Could not encode image: %v\n", err) } }