diff options
Diffstat (limited to 'wipesides.go')
| -rw-r--r-- | wipesides.go | 61 |
1 files changed, 49 insertions, 12 deletions
diff --git a/wipesides.go b/wipesides.go index e4b9ad5..4af3204 100644 --- a/wipesides.go +++ b/wipesides.go @@ -4,8 +4,8 @@ package preproc -// TODO: add minimum size variable (default ~30%?) // TODO: switch to an interface rather than integralimg.I +// TODO: optionally return the edges chosen import ( "errors" @@ -28,24 +28,32 @@ func proportion(i integralimg.I, x int, size int) float64 { // findbestedge goes through every vertical line from x to x+w to // find the one with the lowest proportion of black pixels. +// if there are multiple lines with the same proportion (e.g. zero), +// choose the middle one. func findbestedge(img integralimg.I, x int, w int) int { - var bestx int var best float64 + var bestxs []int if w == 1 { return x } + best = 100 + right := x + w for ; x < right; x++ { prop := proportion(img, x, 1) - if prop > best { + if prop < best { + bestxs = make([]int, 0) best = prop - bestx = x + } + if prop == best { + bestxs = append(bestxs, x) } } + middlex := bestxs[len(bestxs)/2] - return bestx + return middlex } // findedges finds the edges of the main content, by moving a window of wsize @@ -76,6 +84,31 @@ func findedges(img integralimg.I, wsize int, thresh float64) (int, int) { return lowedge, highedge } +// findedgesOutin finds the edges of the main content as findedges does, +// but working from the outside of the image inwards, rather than from the +// middle outwards. +// TODO: test what difference this makes +func findedgesOutin(img integralimg.I, wsize int, thresh float64) (int, int) { + maxx := len(img[0]) - 1 + var lowedge, highedge int = 0, maxx + + for x := maxx-wsize; x > 0; x-- { + if proportion(img, x, wsize) > thresh { + highedge = findbestedge(img, x, wsize) + break + } + } + + for x := 0; x < maxx-wsize; x++ { + if proportion(img, x, wsize) > thresh { + lowedge = findbestedge(img, x, wsize) + break + } + } + + return lowedge, highedge +} + // wipesides fills the sections of image not within the boundaries // of lowedge and highedge with white func wipesides(img *image.Gray, lowedge int, highedge int) *image.Gray { @@ -145,7 +178,8 @@ func Wipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray { func VWipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray { rotimg := sideways(img) integral := integralimg.ToIntegralImg(rotimg) - lowedge, highedge := findedges(integral, wsize, thresh) + // TODO: test whether there are any places where Outin makes a real difference + lowedge, highedge:= findedgesOutin(integral, wsize, thresh) if toonarrow(img, lowedge, highedge, min) { return img } @@ -158,10 +192,13 @@ func VWipe(img *image.Gray, wsize int, thresh float64, min int) *image.Gray { // content area is above min %. // inPath: path of the input image. // outPath: path to save the output image. -// wsize: window size for wipe algorithm. -// thresh: threshold for wipe algorithm. -// min: minimum % of content area width to consider valid. -func WipeFile(inPath string, outPath string, wsize int, thresh float64, min int) error { +// hwsize: window size for horizontal wipe algorithm. +// hthresh: threshold for horizontal wipe algorithm. +// hmin: minimum % of content area width to consider valid. +// vwsize: window size for vertical wipe algorithm. +// vthresh: threshold for vertical wipe algorithm. +// vmin: minimum % of content area height to consider valid. +func WipeFile(inPath string, outPath string, hwsize int, hthresh float64, hmin int, vwsize int, vthresh float64, vmin int) error { f, err := os.Open(inPath) defer f.Close() if err != nil { @@ -175,8 +212,8 @@ func WipeFile(inPath string, outPath string, wsize int, thresh float64, min int) gray := image.NewGray(image.Rect(0, 0, b.Dx(), b.Dy())) draw.Draw(gray, b, img, b.Min, draw.Src) - hclean := Wipe(gray, wsize, thresh, min) - clean := VWipe(hclean, wsize, thresh, min) + hclean := Wipe(gray, hwsize, hthresh, hmin) + clean := VWipe(hclean, vwsize, vthresh, vmin) f, err = os.Create(outPath) if err != nil { |