func newAtFuncGray(p *image.Gray) AtFunc {
return func(x, y int) (r, g, b, a uint32) {
i := p.PixOffset(x, y)
yy := uint32(p.Pix[i])
yy |= yy << 8
return yy, yy, yy, 0xffff
}
}
// Interpolate uint8/pixel images.
func interpolate1x8(src *image.Gray, dstW, dstH int) image.Image {
srcRect := src.Bounds()
srcW := srcRect.Dx()
srcH := srcRect.Dy()
ww, hh := uint64(dstW), uint64(dstH)
dx, dy := uint64(srcW), uint64(srcH)
n, sum := dx*dy, make([]uint64, dstW*dstH)
for y := 0; y < srcH; y++ {
pixOffset := src.PixOffset(0, y)
for x := 0; x < srcW; x++ {
// Get the source pixel.
val64 := uint64(src.Pix[pixOffset])
pixOffset++
// Spread the source pixel over 1 or more destination rows.
py := uint64(y) * hh
for remy := hh; remy > 0; {
qy := dy - (py % dy)
if qy > remy {
qy = remy
}
// Spread the source pixel over 1 or more destination columns.
px := uint64(x) * ww
index := (py/dy)*ww + (px / dx)
for remx := ww; remx > 0; {
qx := dx - (px % dx)
if qx > remx {
qx = remx
}
qxy := qx * qy
sum[index] += val64 * qxy
index++
px += qx
remx -= qx
}
py += qy
remy -= qy
}
}
}
dst := image.NewGray(image.Rect(0, 0, dstW, dstH))
index := 0
for y := 0; y < dstH; y++ {
pixOffset := dst.PixOffset(0, y)
for x := 0; x < dstW; x++ {
dst.Pix[pixOffset] = uint8(sum[index] / n)
pixOffset++
index++
}
}
return dst
}
// grayToY stores the 8x8 region of m whose top-left corner is p in yBlock.
func grayToY(m *image.Gray, p image.Point, yBlock *block) {
b := m.Bounds()
xmax := b.Max.X - 1
ymax := b.Max.Y - 1
pix := m.Pix
for j := 0; j < 8; j++ {
for i := 0; i < 8; i++ {
idx := m.PixOffset(min(p.X+i, xmax), min(p.Y+j, ymax))
yBlock[8*j+i] = int32(pix[idx])
}
}
}
// Fill in missing pixels
func interpolateMissingPixels(img image.Gray, mask []bool) {
var wg sync.WaitGroup
newMask := make([]bool, len(mask), len(mask))
copy(newMask, mask)
couldNotFill := false
imgWidth := img.Bounds().Max.X
imgHeight := img.Bounds().Max.Y
for x := 0; x < imgWidth; x++ {
wg.Add(1)
go func(x int) {
for y := 0; y < imgHeight; y++ {
imgPos := img.PixOffset(x, y)
if mask[imgPos] == true {
continue
}
var sum int
cnt := 0
if x > 0 && mask[imgPos-1] {
sum += int(img.Pix[imgPos-1])
cnt++
}
if x < imgWidth-1 && mask[imgPos+1] {
sum += int(img.Pix[imgPos+1])
cnt++
}
if y > 0 && mask[imgPos-img.Stride] {
sum += int(img.Pix[imgPos-img.Stride])
cnt++
}
if y < imgHeight-1 && mask[imgPos+img.Stride] {
sum += int(img.Pix[imgPos+img.Stride])
cnt++
}
if cnt != 0 {
img.Pix[imgPos] = uint8(sum / cnt)
newMask[imgPos] = true
} else {
couldNotFill = true
}
}
wg.Done()
}(x)
}
wg.Wait()
if couldNotFill {
interpolateMissingPixels(img, newMask)
}
}
//AutoCorrelateProjections calculates a cross-correlation of each radial
//projection with itself
func AutoCorrelateProjections(projections image.Gray) []float64 {
size := projections.Bounds().Size()
width := size.X
nbProj := size.Y
out := make([]float64, nbProj*width)
// for each projection
for θ := 0; θ < nbProj; θ++ {
// log.Println("θ:", θ)
left := projections.PixOffset(0, θ)
right := projections.PixOffset(width, θ)
projection := projections.Pix[left:right]
out = append(out, AutoCorrelateSeries(projection)...)
}
return out
}
func meanVertical(src image.Gray, radius int) (dst image.Gray) {
var wg sync.WaitGroup
norm := float64(radius*2 + 1)
dst = *image.NewGray(src.Bounds())
width, height := src.Bounds().Max.X, src.Bounds().Max.Y
for x := 0; x < width; x++ {
wg.Add(1)
go func(x int) {
total := 0.0
for ky := -radius; ky <= radius; ky++ {
total += float64(src.Pix[src.PixOffset(x, inRange(ky, height))])
}
dst.Pix[dst.PixOffset(x, 0)] = uint8(total / norm)
for y := 1; y < height; y++ {
total -= float64(src.Pix[src.PixOffset(x, inRange(y-radius-1, height))])
total += float64(src.Pix[src.PixOffset(x, inRange(y+radius, height))])
dst.Pix[dst.PixOffset(x, y)] = uint8(total / norm)
}
wg.Done()
}(x)
}
wg.Wait()
return
}
func meanHorizontal(src image.Gray, radius int) (dst image.Gray) {
var wg sync.WaitGroup
norm := float64(radius*2 + 1)
dst = *image.NewGray(src.Bounds())
width, height := src.Bounds().Max.X, src.Bounds().Max.Y
for y := 0; y < height; y++ {
wg.Add(1)
go func(y int) {
total := 0.0
for kx := -radius; kx <= radius; kx++ {
total += float64(src.Pix[src.PixOffset(inRange(kx, width), y)])
}
dst.Pix[dst.PixOffset(0, y)] = uint8(total / norm)
for x := 1; x < width; x++ {
total -= float64(src.Pix[src.PixOffset(inRange(x-radius-1, width), y)])
total += float64(src.Pix[src.PixOffset(inRange(x+radius, width), y)])
dst.Pix[dst.PixOffset(x, y)] = uint8(total / norm)
}
wg.Done()
}(y)
}
wg.Wait()
return
}
func evaluateGrids(src image.Gray, grids []lineGrid) []lineGrid {
for _, grid := range grids {
hCount := len(grid.Horizontal)
vCount := len(grid.Vertical)
fragments := make([]lineFragment, hCount+vCount)
firstVertLine := grid.Vertical[0]
lastVertLine := grid.Vertical[vCount-1]
for j, h := range grid.Horizontal {
_, start := intersection(h, firstVertLine)
_, end := intersection(h, lastVertLine)
fragments[j] = lineFragment{start, end}
}
firstHorizLine := grid.Horizontal[0]
lastHorizLine := grid.Horizontal[hCount-1]
for j, h := range grid.Vertical {
_, start := intersection(h, firstHorizLine)
_, end := intersection(h, lastHorizLine)
fragments[hCount+j] = lineFragment{start, end}
}
score := 0.0
for _, fragment := range fragments {
points := pointsOnLineFragment(fragment)
value := 1.0 / fragment.Length()
for _, point := range points {
if src.Pix[src.PixOffset(point.X, point.Y)] != 0 {
score += value
}
}
}
grid.Score = grid.Score * score / float64(len(fragments))
}
sort.Sort(lineGridByScore(grids))
return grids
}
// copies and resizes src into dst's r
func scaleDownTo(dst *image.Gray, r image.Rectangle, src *image.Gray) error {
if src.Bounds().Dx()%r.Dx() != 0 || src.Bounds().Dy()%r.Dy() != 0 {
return errors.New("Source image size not multiple of rectagle size")
}
dx := src.Bounds().Dx() / r.Dx()
dy := src.Bounds().Dy() / r.Dy()
area := dx * dy
for y := r.Min.Y; y < r.Max.Y; y++ {
for x := r.Min.X; x < r.Max.X; x++ {
col := 0
for v := 0; v < dy; v++ {
for u := 0; u < dx; u++ {
offset := src.PixOffset((x-r.Min.X)*dx+u, (y-r.Min.Y)*dy+v)
col += int(src.Pix[offset])
}
}
dst.SetGray(x, y, color.Gray{uint8(col / area)})
}
}
return nil
}
func (p *perspectiveTrasnformation) warpPerspective(src image.Gray) image.Gray {
var wg sync.WaitGroup
maxX := 0.0
maxY := 0.0
for _, p := range p.dstPoints {
maxX = math.Max(maxX, p.X)
maxY = math.Max(maxY, p.Y)
}
dst := *image.NewGray(image.Rect(0, 0, int(maxX), int(maxY)))
mask := make([]bool, len(dst.Pix), len(dst.Pix))
srcWidth := src.Bounds().Max.X
srcHeight := src.Bounds().Max.Y
for x := 0; x < srcWidth; x++ {
wg.Add(1)
go func(x int) {
for y := 0; y < srcHeight; y++ {
newX, newY := p.Project(float64(x), float64(y))
if newX < 0 || newX >= maxX || newY < 0 || newY >= maxY {
continue
}
g := src.Pix[src.PixOffset(x, y)]
dstPos := dst.PixOffset(int(newX), int(newY))
dst.Pix[dstPos] = g
mask[dstPos] = true
}
wg.Done()
}(x)
}
wg.Wait()
interpolateMissingPixels(dst, mask)
return dst
}
func sdfize(img *image.Gray) {
w := img.Bounds().Size().X
h := img.Bounds().Size().Y
g1 := make([]xys, w*h)
g2 := make([]xys, w*h)
for y := 0; y < h; y++ {
for x := 0; x < w; x++ {
a := img.Pix[img.PixOffset(x, y)]
if a < 0x7F {
g2[y*w+x] = infinity
} else {
g1[y*w+x] = infinity
}
}
}
generateSDF(int16(w), int16(h), g1)
generateSDF(int16(w), int16(h), g2)
for y := 0; y < h; y++ {
for x := 0; x < w; x++ {
pos := y*w + x
dist1 := distance(g1[pos].x, g1[pos].y)
dist2 := distance(g2[pos].x, g2[pos].y)
dist := 2 * 128 * (dist1 - dist2) / float64(w)
if dist < -128 {
dist = -128
} else if dist > 127 {
dist = 127
}
c := uint8(128 + dist)
img.SetGray(x, y, color.Gray{c})
}
}
}
// Scale the source image down to the destination image.
// Preserves aspect ratio, leaving unused destination pixels untouched.
// At present it just uses a simple box filter.
// It might be possible to improve performance and clarity by making all
// pixel fractions 1/16 and using essentially fixed-point arithmetic.
func scaleDown(src SippImage, dst *image.Gray) {
srcRect := src.Bounds()
dstRect := dst.Bounds()
//fmt.Println("srcRect:<", srcRect, ">")
//fmt.Println("dstRect:<", dstRect, ">")
srcWidth := srcRect.Dx()
srcHeight := srcRect.Dy()
dstWidth := dstRect.Dx()
dstHeight := dstRect.Dy()
//fmt.Println("srcWidth:<", srcWidth, ">")
//fmt.Println("srcHeight:<", srcHeight, ">")
//fmt.Println("dstWidth:<", dstWidth, ">")
//fmt.Println("dstHeight:<", dstHeight, ">")
srcAR := float64(srcWidth) / float64(srcHeight)
dstAR := float64(dstWidth) / float64(dstHeight)
//fmt.Println("srcAR:<", srcAR, ">")
//fmt.Println("dstAR:<", dstAR, ">")
var scale float64
var outWidth int
var outHeight int
if srcAR < dstAR {
// scale vertically and use a horizontal offset
scale = float64(srcHeight) / float64(dstHeight)
outWidth = int(float64(srcWidth) / scale)
outHeight = dstHeight
//fmt.Println("Scaling vertically")
} else {
// scale horizontally and use a vertical offset
scale = float64(srcWidth) / float64(dstWidth)
outHeight = int(float64(srcHeight) / scale)
outWidth = dstWidth
//fmt.Println("Scaling horizontally")
}
//fmt.Println("scale:<", scale, ">")
//fmt.Println("outWidth:<", outWidth, ">")
//fmt.Println("outHeight:<", outHeight, ">")
// One of the following will be 0.
hoff := (dstWidth - outWidth) / 2
voff := (dstHeight - outHeight) / 2
// Scale 16-bit images down to 8. We incour the cost spuriously for 8-bit
// images so that we can access the source polymorphically.
var scaleBpp float64 = 1.0
if src.Bpp() == 16 {
scaleBpp = 1.0 / 256.0
}
//fmt.Println("scaleBpp:", scaleBpp)
hfilter := preComputeFilter(scale, outWidth, srcWidth, scaleBpp)
intrm := image.NewGray(image.Rect(0, 0, outWidth, srcHeight))
for inty := 0; inty < srcHeight; inty++ {
// Apply the filter to the source row, generating an intermediate row
for intx := 0; intx < outWidth; intx++ {
var val float64
for i := 0; i < hfilter[intx].n; i++ {
val = val + src.Val(hfilter[intx].idx+i, inty)*hfilter[intx].weights[i]
}
val = math.Floor(val + 0.5)
if val > 255.0 {
intrm.Pix[intrm.PixOffset(intx, inty)] = 255
} else {
intrm.Pix[intrm.PixOffset(intx, inty)] = uint8(val)
}
}
}
vfilter := preComputeFilter(scale, outHeight, srcHeight, 1.0)
for outx := 0; outx < outWidth; outx++ {
// Apply the filter to the intermediate column, generating an output column
for outy := 0; outy < outHeight; outy++ {
var val float64
for i := 0; i < vfilter[outy].n; i++ {
index := intrm.PixOffset(outx, vfilter[outy].idx+i)
val = val + float64(intrm.Pix[index])*vfilter[outy].weights[i]
}
dst.Pix[dst.PixOffset(outx+hoff, outy+voff)] = uint8(math.Floor(val + 0.5))
}
}
}
func newSetFuncGray(p *image.Gray) SetFunc {
return func(x, y int, r, g, b, a uint32) {
i := p.PixOffset(x, y)
p.Pix[i] = uint8(((299*r + 587*g + 114*b + 500) / 1000) >> 8)
}
}
func houghLines(src image.Gray, thetas []float64, threshold uint64, limit int) []polarLine {
if thetas == nil {
thetas = generateThetas(-math.Pi/2, math.Pi/2, math.Pi/180.0)
}
maxY, maxX := src.Bounds().Max.Y, src.Bounds().Max.X
maxR := 2 * math.Hypot(float64(maxX), float64(maxY))
offset := maxR / 2
hAcc := make([][]uint64, int(maxR), int(maxR))
for i := range hAcc {
hAcc[i] = make([]uint64, len(thetas), len(thetas))
}
sin := make([]float64, len(thetas), len(thetas))
cos := make([]float64, len(thetas), len(thetas))
for i, th := range thetas {
sin[i] = math.Sin(th)
cos[i] = math.Cos(th)
}
var wg sync.WaitGroup
for y := 0; y < maxY; y++ {
wg.Add(1)
go func(y int) {
for x := 0; x < maxX; x++ {
val := src.Pix[src.PixOffset(x, y)]
if val == 0 {
continue
}
for i := range thetas {
r := float64(x)*cos[i] + float64(y)*sin[i]
iry := int(r + offset)
atomic.AddUint64(&hAcc[iry][i], 1)
}
}
wg.Done()
}(y)
}
wg.Wait()
linesSet := make(map[string]bool)
var lines []polarLine
for i := range hAcc {
r := i - int(offset)
thetaOffset := 0.0
if r < 0 {
thetaOffset = math.Pi
r *= -1
}
for j, count := range hAcc[i] {
if count < 2 || count < threshold {
continue
}
line := polarLine{
Theta: thetas[j] + thetaOffset,
Distance: r,
Count: count,
}
hash := line.HashKey()
if !linesSet[hash] {
linesSet[hash] = true
lines = append(lines, line)
}
}
}
sort.Sort(polarLinesByCount(lines))
if limit > 0 && len(lines) > limit {
lines = lines[:limit]
}
return lines
}