img.SmoothGaussian(size, size, standardDeviation, standardDeviation)
-let findMaxima (img: Image<Gray, byte>) : IEnumerable<HashSet<Point>> =
- use suppress = new Image<Gray, byte>(img.Size)
+type Points = HashSet<Point>
+
+let drawPoints (img: Image<Gray, byte>) (points: Points) (intensity: byte) =
+ for p in points do
+ img.Data.[p.Y, p.X, 0] <- intensity
+
+
+type ExtremumType =
+ | Maxima = 1
+ | Minima = 2
+
+let findExtremum (img: Image<Gray, byte>) (extremumType: ExtremumType) : IEnumerable<Points> =
let w = img.Width
let h = img.Height
+ let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
let imgData = img.Data
- let suppressData = suppress.Data
+ let suppress: bool[,] = Array2D.zeroCreate h w
let result = List<List<Point>>()
while betterLevelToCheck.Count > 0 do
let p = betterLevelToCheck.Pop()
- if suppressData.[p.Y, p.X, 0] = 0uy
+ if not suppress.[p.Y, p.X]
then
- suppressData.[p.Y, p.X, 0] <- 1uy
+ suppress.[p.Y, p.X] <- true
sameLevelToCheck.Push(p)
let current = List<Point>()
let p' = sameLevelToCheck.Pop()
let currentLevel = imgData.[p'.Y, p'.X, 0]
current.Add(p') |> ignore
- for i in -1 .. 1 do
- for j in -1 .. 1 do
- if i <> 0 || j <> 0
+ for i, j in se do
+ let ni = i + p'.Y
+ let nj = j + p'.X
+ if ni >= 0 && ni < h && nj >= 0 && nj < w
+ then
+ let level = imgData.[ni, nj, 0]
+ let notSuppressed = not suppress.[ni, nj]
+
+ if level = currentLevel && notSuppressed
then
- let ni = i + p'.Y
- let nj = j + p'.X
- if ni >= 0 && ni < h && nj >= 0 && nj < w
+ suppress.[ni, nj] <- true
+ sameLevelToCheck.Push(Point(nj, ni))
+ elif if extremumType = ExtremumType.Maxima then level > currentLevel else level < currentLevel
+ then
+ betterExists <- true
+ if notSuppressed
then
- let level = imgData.[ni, nj, 0]
- let notSuppressed = suppressData.[ni, nj, 0] = 0uy
-
- if level = currentLevel && notSuppressed
- then
- suppressData.[ni, nj, 0] <- 1uy
- sameLevelToCheck.Push(Point(nj, ni))
- elif level > currentLevel
- then
- betterExists <- true
- if notSuppressed
- then
- betterLevelToCheck.Push(Point(nj, ni))
+ betterLevelToCheck.Push(Point(nj, ni))
if not betterExists
then
for j in 0 .. w - 1 do
let maxima = flood (Point(j, i))
if maxima.Count > 0
- then result.AddRange(maxima)
+ then
+ result.AddRange(maxima)
+
+ result.Select(fun l -> Points(l))
+
- result.Select(fun l -> HashSet<Point>(l))
+let findMaxima (img: Image<Gray, byte>) : IEnumerable<Points> =
+ findExtremum img ExtremumType.Maxima
+
+let findMinima (img: Image<Gray, byte>) : IEnumerable<Points> =
+ findExtremum img ExtremumType.Minima
type PriorityQueue () =
- let q = List<HashSet<Point>>() // TODO: Check performance with an HasSet
+ let size = 256
+ let q: Points[] = Array.init size (fun i -> Points())
let mutable highest = -1 // Value of the first elements of 'q'.
+ let mutable lowest = size
- member this.Next () : byte * Point =
+ member this.NextMax () : byte * Point =
if this.IsEmpty
then
invalidOp "Queue is empty"
else
- let l = q.[0]
+ let l = q.[highest]
let next = l.First()
l.Remove(next) |> ignore
let value = byte highest
+
if l.Count = 0
then
- q.RemoveAt(0)
highest <- highest - 1
- while q.Count > 0 && q.[0] = null do
- q.RemoveAt(0)
+ while highest > lowest && q.[highest].Count = 0 do
highest <- highest - 1
+ if highest = lowest
+ then
+ highest <- -1
+ lowest <- size
+
+ value, next
+
+ member this.NextMin () : byte * Point =
+ if this.IsEmpty
+ then
+ invalidOp "Queue is empty"
+ else
+ let l = q.[lowest + 1]
+ let next = l.First()
+ l.Remove(next) |> ignore
+ let value = byte (lowest + 1)
+
+ if l.Count = 0
+ then
+ lowest <- lowest + 1
+ while lowest < highest && q.[lowest + 1].Count = 0 do
+ lowest <- lowest + 1
+ if highest = lowest
+ then
+ highest <- -1
+ lowest <- size
+
value, next
member this.Max =
highest |> byte
- (*member this.UnionWith (other: PriorityQueue) =
- while not other.IsEmpty do
- let p, v = other.Next
- this.Add p v*)
+ member this.Min =
+ lowest + 1 |> byte
member this.Add (value: byte) (p: Point) =
let vi = int value
- if this.IsEmpty
- then
- highest <- int value
- q.Insert(0, null)
- elif vi > highest
+ if vi > highest
then
- for i in highest .. vi - 1 do
- q.Insert(0, null)
highest <- vi
- elif highest - vi >= q.Count
+ if vi <= lowest
then
- for i in 0 .. highest - vi - q.Count do
- q.Add(null)
+ lowest <- vi - 1
- let pos = highest - vi
- if q.[pos] = null
+ q.[vi].Add(p) |> ignore
+
+ member this.Remove (value: byte) (p: Point) =
+ let vi = int value
+ if q.[vi].Remove(p) && q.[vi].Count = 0
then
- q.[pos] <- HashSet<Point>([p])
- else
- q.[pos].Add(p) |> ignore
+ if vi = highest
+ then
+ highest <- highest - 1
+ while highest > lowest && q.[highest].Count = 0 do
+ highest <- highest - 1
+ elif vi - 1 = lowest
+ then
+ lowest <- lowest + 1
+ while lowest < highest && q.[lowest + 1].Count = 0 do
+ lowest <- lowest + 1
+ if highest = lowest // The queue is now empty.
+ then
+ highest <- -1
+ lowest <- size
member this.IsEmpty =
- q.Count = 0
+ highest = -1
member this.Clear () =
- while highest >= 0 do
- q.[highest] <- null
+ while highest > lowest do
+ q.[highest].Clear()
highest <- highest - 1
+ highest <- -1
+ lowest <- size
+type private AreaState =
+ | Removed = 1
+ | Unprocessed = 2
+ | Validated = 3
-type MaximaState = Uncertain | Validated | TooBig
-type Maxima = {
- elements : HashSet<Point>
- mutable intensity: byte option
- mutable state: MaximaState }
+type private AreaOperation =
+ | Opening = 1
+ | Closing = 2
+[<AllowNullLiteral>]
+type private Area (elements: Points) =
+ member this.Elements = elements
+ member val Intensity = None with get, set
+ member val State = AreaState.Unprocessed with get, set
-let areaOpen (img: Image<Gray, byte>) (area: int) =
+let private areaOperation (img: Image<Gray, byte>) (area: int) (op: AreaOperation) =
let w = img.Width
let h = img.Height
+ let imgData = img.Data
+ let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
- let maxima = findMaxima img |> Seq.map (fun m -> { elements = m; intensity = None; state = Uncertain }) |> List.ofSeq
- let toValidated = Stack<Maxima>(maxima)
+ let areas = List<Area>((if op = AreaOperation.Opening then findMaxima img else findMinima img) |> Seq.map Area)
- while toValidated.Count > 0 do
- let m = toValidated.Pop()
- if m.elements.Count <= area
+ let pixels: Area[,] = Array2D.create h w null
+ for m in areas do
+ for e in m.Elements do
+ pixels.[e.Y, e.X] <- m
+
+ let queue = PriorityQueue()
+
+ let addEdgeToQueue (elements: Points) =
+ for p in elements do
+ for i, j in se do
+ let ni = i + p.Y
+ let nj = j + p.X
+ let p' = Point(nj, ni)
+ if ni >= 0 && ni < h && nj >= 0 && nj < w && not (elements.Contains(p'))
+ then
+ queue.Add (imgData.[ni, nj, 0]) p'
+
+ // Reverse order is quicker.
+ for i in areas.Count - 1 .. -1 .. 0 do
+ let m = areas.[i]
+ if m.Elements.Count <= area && m.State <> AreaState.Removed
then
- let queue =
- let q = PriorityQueue()
- let firstElements = HashSet<Point>()
- for p in m.elements do
- for i in -1 .. 1 do
- for j in -1 .. 1 do
- if i <> 0 || j <> 0
- then
- let ni = i + p.Y
- let nj = j + p.X
- let p' = Point(nj, ni)
- if ni >= 0 && ni < h && nj >= 0 && nj < w && not (m.elements.Contains(p')) && not (firstElements.Contains(p'))
- then
- firstElements.Add(p') |> ignore
- q.Add (img.Data.[ni, nj, 0]) p'
- q
+ queue.Clear()
+ addEdgeToQueue m.Elements
- let mutable intensity = queue.Max
- let nextElements = HashSet<Point>()
+ let mutable intensity = if op = AreaOperation.Opening then queue.Max else queue.Min
+ let nextElements = Points()
let mutable stop = false
while not stop do
- let intensity', p = queue.Next ()
+ let intensity', p = if op = AreaOperation.Opening then queue.NextMax () else queue.NextMin ()
+ let mutable merged = false
if intensity' = intensity // The intensity doesn't change.
then
- if m.elements.Count + nextElements.Count + 1 > area
+ if m.Elements.Count + nextElements.Count + 1 > area
then
- m.state <- Validated
- m.intensity <- Some intensity
+ m.State <- AreaState.Validated
+ m.Intensity <- Some intensity
stop <- true
else
nextElements.Add(p) |> ignore
- elif intensity' < intensity
+
+ elif if op = AreaOperation.Opening then intensity' < intensity else intensity' > intensity
then
- m.elements.UnionWith(nextElements)
- if m.elements.Count = area
+ m.Elements.UnionWith(nextElements)
+ for e in nextElements do
+ pixels.[e.Y, e.X] <- m
+
+ if m.Elements.Count = area
then
- m.state <- Validated
- m.intensity <- Some (intensity')
+ m.State <- AreaState.Validated
+ m.Intensity <- Some (intensity')
stop <- true
else
intensity <- intensity'
nextElements.Clear()
nextElements.Add(p) |> ignore
- else // i' > i
- seq {
- for m' in maxima do
- if m' <> m && m'.elements.Contains(p) then
- if m'.elements.Count + m.elements.Count <= area
- then
- m'.state <- Uncertain
- m'.elements.UnionWith(m.elements)
- if not <| toValidated.Contains m' // FIXME: Maybe use state instead of scanning the whole list.
- then
- toValidated.Push(m')
- stop <- true
- yield false
- } |> Seq.forall id |> ignore
- if not stop
+ else
+ let m' = pixels.[p.Y, p.X]
+ if m' <> null
then
- m.state <- Validated
- m.intensity <- Some (intensity)
+ if m'.Elements.Count + m.Elements.Count <= area
+ then
+ m'.State <- AreaState.Removed
+ for e in m'.Elements do
+ pixels.[e.Y, e.X] <- m
+ queue.Remove imgData.[e.Y, e.X, 0] e
+ addEdgeToQueue m'.Elements
+ m.Elements.UnionWith(m'.Elements)
+ let intensityMax = if op = AreaOperation.Opening then queue.Max else queue.Min
+ if intensityMax <> intensity
+ then
+ intensity <- intensityMax
+ nextElements.Clear()
+ merged <- true
+
+ if not merged
+ then
+ m.State <- AreaState.Validated
+ m.Intensity <- Some (intensity)
stop <- true
- if not stop
+ if not stop && not merged
then
- for i in -1 .. 1 do
- for j in -1 .. 1 do
- if i <> 0 || j <> 0
- then
- let ni = i + p.Y
- let nj = j + p.X
- let p' = Point(nj, ni)
- if ni < 0 || ni >= h || nj < 0 || nj >= w
- then
- m.state <- Validated
- m.intensity <- Some (intensity)
- stop <- true
- elif not (m.elements.Contains(p')) && not (nextElements.Contains(p'))
- then
- queue.Add (img.Data.[ni, nj, 0]) p'
+ for i, j in se do
+ let ni = i + p.Y
+ let nj = j + p.X
+ let p' = Point(nj, ni)
+ if ni < 0 || ni >= h || nj < 0 || nj >= w
+ then
+ m.State <- AreaState.Validated
+ m.Intensity <- Some (intensity)
+ stop <- true
+ elif not (m.Elements.Contains(p')) && not (nextElements.Contains(p'))
+ then
+ queue.Add (imgData.[ni, nj, 0]) p'
if queue.IsEmpty
then
- if m.elements.Count + nextElements.Count <= area
+ if m.Elements.Count + nextElements.Count <= area
then
- m.state <- Validated
- m.intensity <- Some intensity'
- m.elements.UnionWith(nextElements)
+ m.State <- AreaState.Validated
+ m.Intensity <- Some intensity'
+ m.Elements.UnionWith(nextElements)
stop <- true
- for m in maxima do
- if m.state = Validated
+ for m in areas do
+ if m.State = AreaState.Validated
then
- match m.intensity with
+ match m.Intensity with
| Some i ->
- for p in m.elements do
- img.Data.[p.Y, p.X, 0] <- i
+ for p in m.Elements do
+ imgData.[p.Y, p.X, 0] <- i
| _ -> ()
()
+let areaOpen (img: Image<Gray, byte>) (area: int) =
+ areaOperation img area AreaOperation.Opening
+
+let areaClose (img: Image<Gray, byte>) (area: int) =
+ areaOperation img area AreaOperation.Closing
+
+let areaOpen2 (img: Image<Gray, byte>) (area: int) =
+ let w = img.Width
+ let h = img.Height
+ let imgData = img.Data
+ let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
+
+ let histogram = Array.zeroCreate 256
+ for i in 0 .. h - 1 do
+ for j in 0 .. w - 1 do
+ let v = imgData.[i, j, 0] |> int
+ histogram.[v] <- histogram.[v] + 1
+
+ let flooded : bool[,] = Array2D.zeroCreate h w
+
+ let pointsChecked = HashSet<Point>()
+ let pointsToCheck = Stack<Point>()
+
+ for level in 255 .. -1 .. 0 do
+ let mutable n = histogram.[level]
+ if n > 0
+ then
+ for i in 0 .. h - 1 do
+ for j in 0 .. w - 1 do
+ if not flooded.[i, j] && imgData.[i, j, 0] = byte level
+ then
+ let mutable maxNeighborValue = 0uy
+ pointsChecked.Clear()
+ pointsToCheck.Clear()
+ pointsToCheck.Push(Point(j, i))
+
+ while pointsToCheck.Count > 0 do
+ let next = pointsToCheck.Pop()
+ pointsChecked.Add(next) |> ignore
+ flooded.[next.Y, next.X] <- true
+
+ for nx, ny in se do
+ let p = Point(next.X + nx, next.Y + ny)
+ if p.X >= 0 && p.X < w && p.Y >= 0 && p.Y < h
+ then
+ let v = imgData.[p.Y, p.X, 0]
+ if v = byte level
+ then
+ if not (pointsChecked.Contains(p))
+ then
+ pointsToCheck.Push(p)
+ elif v > maxNeighborValue
+ then
+ maxNeighborValue <- v
+
+ if int maxNeighborValue < level && pointsChecked.Count <= area
+ then
+ for p in pointsChecked do
+ imgData.[p.Y, p.X, 0] <- maxNeighborValue
+
+
// Zhang and Suen algorithm.
// Modify 'mat' in place.
let thin (mat: Matrix<byte>) =
let w = img.Width
let h = img.Height
- let pointChecked = HashSet<Point>()
+ let pointChecked = Points()
let pointToCheck = List<Point>(startPoints);
let data = img.Data
projects / master-thesis.git / blobdiff