diff options
Diffstat (limited to 'wipesides.go')
| -rw-r--r-- | wipesides.go | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/wipesides.go b/wipesides.go index a306250..7480a7f 100644 --- a/wipesides.go +++ b/wipesides.go @@ -19,17 +19,22 @@ import ( "rescribe.xyz/integralimg" ) -// returns the proportion of the given window that is black pixels -func proportion(i ImageWindower, x int, size int) float64 { - w := i.GetVerticalWindow(x, size) - return w.Proportion() +// ProportionSlice returns the proportion of black pixels in a +// vertical slice of an image starting at x, width pixels wide. +func ProportionSlice(i SummableImage, x int, width int) float64 { + r := image.Rect(x, 0, x + width, i.Bounds().Dy()) + in := r.Intersect(i.Bounds()) + area := in.Dx() * in.Dy() + // 1 << 16 - 1 as we're using Gray16, so 1 << 16 - 1 = white + numwhite := float64(i.Sum(in)) / float64(1 << 16 - 1) + return float64(area) / float64(numwhite) - 1 } // 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 ImageWindower, x int, w int) int { +func findbestedge(img SummableImage, x int, w int) int { var best float64 var bestxs []int @@ -41,7 +46,7 @@ func findbestedge(img ImageWindower, x int, w int) int { right := x + w for ; x < right; x++ { - prop := proportion(img, x, 1) + prop := ProportionSlice(img, x, 1) if prop < best { bestxs = make([]int, 0) best = prop @@ -55,10 +60,10 @@ func findbestedge(img ImageWindower, x int, w int) int { return middlex } -// findedges finds the edges of the main content, by moving a window of wsize +// findedges finds the edges of the main content, by moving a wsize width vertical slice // from near 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(img ImageWindower, wsize int, thresh float64) (int, int) { +func findedges(img SummableImage, wsize int, thresh float64) (int, int) { maxx := img.Bounds().Dx() - 1 var lowedge, highedge int = 0, maxx @@ -67,14 +72,14 @@ func findedges(img ImageWindower, wsize int, thresh float64) (int, int) { notcentre := maxx / 10 for x := maxx/2 + notcentre; x < maxx-wsize; x++ { - if proportion(img, x, wsize) <= thresh { + if ProportionSlice(img, x, wsize) <= thresh { highedge = findbestedge(img, x, wsize) break } } for x := maxx/2 - notcentre; x > 0; x-- { - if proportion(img, x, wsize) <= thresh { + if ProportionSlice(img, x, wsize) <= thresh { lowedge = findbestedge(img, x, wsize) break } @@ -87,19 +92,19 @@ func findedges(img ImageWindower, wsize int, thresh float64) (int, int) { // but working from the outside of the image inwards, rather than from the // middle outwards. // TODO: test what difference this makes -func findedgesOutin(img ImageWindower, wsize int, thresh float64) (int, int) { +func findedgesOutin(img SummableImage, wsize int, thresh float64) (int, int) { maxx := img.Bounds().Dx() - 1 var lowedge, highedge int = 0, maxx for x := maxx-wsize; x > 0; x-- { - if proportion(img, x, wsize) > thresh { + if ProportionSlice(img, x, wsize) > thresh { highedge = findbestedge(img, x, wsize) break } } for x := 0; x < maxx-wsize; x++ { - if proportion(img, x, wsize) > thresh { + if ProportionSlice(img, x, wsize) > thresh { lowedge = findbestedge(img, x, wsize) break } @@ -196,10 +201,10 @@ 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. -// hwsize: window size for horizontal wipe algorithm. +// hwsize: window size (width) 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. +// vwsize: window size (height) 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 { |