Parasitemia/Parasitemia/ImgTools.fs

   1 module ImgTools
   2
   3 open System
   4 open System.Drawing
   5 open System.Collections.Generic
   6 open System.Linq
   7
   8 open Emgu.CV
   9 open Emgu.CV.Structure
  10
  11 open Utils
  12 open Heap
  13
  14 // Normalize image values between 0uy and 255uy.
  15 let normalizeAndConvert (img: Image<Gray, float32>) : Image<Gray, byte> =
  16     let min = ref [| 0.0 |]
  17     let minLocation = ref <| [| Point() |]
  18     let max = ref [| 0.0 |]
  19     let maxLocation = ref <| [| Point() |]
  20     img.MinMax(min, max, minLocation, maxLocation)
  21     ((img - (!min).[0]) / ((!max).[0] - (!min).[0]) * 255.0).Convert<Gray, byte>()
  22
  23
  24 let saveImg (img: Image<'TColor, 'TDepth>) (filepath: string) =
  25     img.Save(filepath)
  26
  27
  28 let saveMat (mat: Matrix<'TDepth>) (filepath: string) =
  29     use img = new Image<Gray, 'TDeph>(mat.Size)
  30     mat.CopyTo(img)
  31     saveImg img filepath
  32
  33
  34 let suppressMConnections (img: Matrix<byte>) =
  35     let w = img.Width
  36     let h = img.Height
  37     for i in 1 .. h - 2 do
  38         for j in 1 .. w - 2 do
  39             if img.[i, j] > 0uy && img.Data.[i + 1, j] > 0uy && (img.Data.[i, j - 1] > 0uy && img.Data.[i - 1, j + 1] = 0uy || img.Data.[i, j + 1] > 0uy && img.Data.[i - 1, j - 1] = 0uy)
  40             then
  41                 img.[i, j] <- 0uy
  42     for i in 1 .. h - 2 do
  43         for j in 1 .. w - 2 do
  44             if img.[i, j] > 0uy && img.Data.[i - 1, j] > 0uy && (img.Data.[i, j - 1] > 0uy && img.Data.[i + 1, j + 1] = 0uy || img.Data.[i, j + 1] > 0uy && img.Data.[i + 1, j - 1] = 0uy)
  45             then
  46                 img.[i, j] <- 0uy
  47
  48 let findEdges (img: Image<Gray, float32>) : Matrix<byte> * Image<Gray, float> * Image<Gray, float> =
  49     let w = img.Width
  50     let h = img.Height
  51
  52     use sobelKernel =
  53         new ConvolutionKernelF(array2D [[ 1.0f; 0.0f; -1.0f ]
  54                                         [ 2.0f; 0.0f; -2.0f ]
  55                                         [ 1.0f; 0.0f; -1.0f ]], Point(1, 1))
  56
  57     let xGradient = img.Convolution(sobelKernel).Convert<Gray, float>()
  58     let yGradient = img.Convolution(sobelKernel.Transpose()).Convert<Gray, float>()
  59
  60     let xGradientData = xGradient.Data
  61     let yGradientData = yGradient.Data
  62     for r in 0 .. h - 1 do
  63         xGradientData.[r, 0, 0] <- 0.0
  64         xGradientData.[r, w - 1, 0] <- 0.0
  65         yGradientData.[r, 0, 0] <- 0.0
  66         yGradientData.[r, w - 1, 0] <- 0.0
  67
  68     for c in 0 .. w - 1 do
  69         xGradientData.[0, c, 0] <- 0.0
  70         xGradientData.[h - 1, c, 0] <- 0.0
  71         yGradientData.[0, c, 0] <- 0.0
  72         yGradientData.[h - 1, c, 0] <- 0.0
  73
  74     use magnitudes = new Matrix<float>(xGradient.Size)
  75     CvInvoke.CartToPolar(xGradient, yGradient, magnitudes, new Mat()) // Compute the magnitudes (without angles).
  76
  77     let thresholdHigh, thresholdLow =
  78         let sensibility = 0.1
  79         use magnitudesByte = magnitudes.Convert<byte>()
  80         let threshold = CvInvoke.Threshold(magnitudesByte, magnitudesByte, 0.0, 1.0, CvEnum.ThresholdType.Otsu ||| CvEnum.ThresholdType.Binary)
  81         threshold + (sensibility * threshold), threshold - (sensibility * threshold)
  82
  83     // Non-maximum suppression.
  84     use nms = new Matrix<byte>(xGradient.Size)
  85     nms.SetValue(1.0)
  86
  87     for i in 0 .. h - 1 do
  88         nms.Data.[i, 0] <- 0uy
  89         nms.Data.[i, w - 1] <- 0uy
  90
  91     for j in 0 .. w - 1 do
  92         nms.Data.[0, j] <- 0uy
  93         nms.Data.[h - 1, j] <- 0uy
  94
  95     for i in 1 .. h - 2 do
  96         for j in 1 .. w - 2 do
  97             let vx = xGradient.Data.[i, j, 0]
  98             let vy = yGradient.Data.[i, j, 0]
  99             let angle =
 100                 let a = atan2 vy vx
 101                 if a < 0.0 then 2. * Math.PI + a else a
 102
 103             let mNeigbors (sign: int) : float =
 104                 if angle < Math.PI / 8. || angle >= 15.0 * Math.PI / 8. then magnitudes.Data.[i, j + sign]
 105                 elif angle < 3.0 * Math.PI / 8. then magnitudes.Data.[i + sign, j + sign]
 106                 elif angle < 5.0 * Math.PI / 8. then magnitudes.Data.[i + sign, j]
 107                 elif angle < 7.0 * Math.PI / 8. then magnitudes.Data.[i + sign, j - sign]
 108                 elif angle < 9.0 * Math.PI / 8. then magnitudes.Data.[i, j - sign]
 109                 elif angle < 11.0 * Math.PI / 8. then magnitudes.Data.[i - sign, j - sign]
 110                 elif angle < 13.0 * Math.PI / 8. then magnitudes.Data.[i - sign, j]
 111                 else magnitudes.Data.[i - sign, j + sign]
 112
 113             let m = magnitudes.Data.[i, j]
 114             if m < mNeigbors 1 || m < mNeigbors -1 || m < thresholdLow
 115             then
 116                 nms.Data.[i, j] <- 0uy
 117
 118     // suppressMConnections nms // It's not usefull for the rest of the process (ellipse detection).
 119
 120     let edges = new Matrix<byte>(xGradient.Size)
 121
 122     // Histeresis thresholding.
 123     let toVisit = Stack<Point>()
 124     for i in 0 .. h - 1 do
 125         for j in 0 .. w - 1 do
 126             if nms.Data.[i, j] = 1uy && magnitudes.Data.[i, j] >= thresholdHigh
 127             then
 128                 nms.Data.[i, j] <- 0uy
 129                 toVisit.Push(Point(j, i))
 130                 while toVisit.Count > 0 do
 131                     let p = toVisit.Pop()
 132                     edges.Data.[p.Y, p.X] <- 1uy
 133                     for i' in -1 .. 1  do
 134                         for j' in -1 .. 1 do
 135                             if i' <> 0 || j' <> 0
 136                             then
 137                                 let ni = p.Y + i'
 138                                 let nj = p.X + j'
 139                                 if ni >= 0 && ni < h && nj >= 0 && nj < w && nms.Data.[ni, nj] = 1uy
 140                                 then
 141                                     nms.Data.[ni, nj] <- 0uy
 142                                     toVisit.Push(Point(nj, ni))
 143
 144
 145     edges, xGradient, yGradient
 146
 147
 148 let gaussianFilter (img : Image<'TColor, 'TDepth>) (standardDeviation : float) : Image<'TColor, 'TDepth> =
 149     let size = 2 * int (ceil (4.0 * standardDeviation)) + 1
 150     img.SmoothGaussian(size, size, standardDeviation, standardDeviation)
 151
 152
 153 type Points = HashSet<Point>
 154
 155 let drawPoints (img: Image<Gray, byte>) (points: Points) (intensity: byte) =
 156     for p in points do
 157         img.Data.[p.Y, p.X, 0] <- intensity
 158
 159 type ExtremumType =
 160     | Maxima = 1
 161     | Minima = 2
 162
 163 let findExtremum (img: Image<Gray, byte>) (extremumType: ExtremumType) : IEnumerable<Points> =
 164     let w = img.Width
 165     let h = img.Height
 166     let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
 167
 168     let imgData = img.Data
 169     let suppress: bool[,] = Array2D.zeroCreate h w
 170
 171     let result = List<List<Point>>()
 172
 173     let flood (start: Point) : List<List<Point>> =
 174         let sameLevelToCheck = Stack<Point>()
 175         let betterLevelToCheck = Stack<Point>()
 176         betterLevelToCheck.Push(start)
 177
 178         let result' = List<List<Point>>()
 179
 180         while betterLevelToCheck.Count > 0 do
 181             let p = betterLevelToCheck.Pop()
 182             if not suppress.[p.Y, p.X]
 183             then
 184                 suppress.[p.Y, p.X] <- true
 185                 sameLevelToCheck.Push(p)
 186                 let current = List<Point>()
 187
 188                 let mutable betterExists = false
 189
 190                 while sameLevelToCheck.Count > 0 do
 191                     let p' = sameLevelToCheck.Pop()
 192                     let currentLevel = imgData.[p'.Y, p'.X, 0]
 193                     current.Add(p') |> ignore
 194                     for i, j in se do
 195                         let ni = i + p'.Y
 196                         let nj = j + p'.X
 197                         if ni >= 0 && ni < h && nj >= 0 && nj < w
 198                         then
 199                             let level = imgData.[ni, nj, 0]
 200                             let notSuppressed = not suppress.[ni, nj]
 201
 202                             if level = currentLevel && notSuppressed
 203                             then
 204                                 suppress.[ni, nj] <- true
 205                                 sameLevelToCheck.Push(Point(nj, ni))
 206                             elif if extremumType = ExtremumType.Maxima then level > currentLevel else level < currentLevel
 207                             then
 208                                 betterExists <- true
 209                                 if notSuppressed
 210                                 then
 211                                     betterLevelToCheck.Push(Point(nj, ni))
 212
 213                 if not betterExists
 214                 then
 215                     result'.Add(current)
 216         result'
 217
 218     for i in 0 .. h - 1 do
 219         for j in 0 .. w - 1 do
 220             let maxima = flood (Point(j, i))
 221             if maxima.Count > 0
 222             then
 223                 result.AddRange(maxima)
 224
 225     result.Select(fun l -> Points(l))
 226
 227
 228 let findMaxima (img: Image<Gray, byte>) : IEnumerable<Points> =
 229     findExtremum img ExtremumType.Maxima
 230
 231 let findMinima (img: Image<Gray, byte>) : IEnumerable<Points> =
 232     findExtremum img ExtremumType.Minima
 233
 234
 235 type PriorityQueue () =
 236     let size = 256
 237     let q: Points[] = Array.init size (fun i -> Points())
 238     let mutable highest = -1 // Value of the first elements of 'q'.
 239     let mutable lowest = size
 240
 241     member this.NextMax () : byte * Point =
 242         if this.IsEmpty
 243         then
 244             invalidOp "Queue is empty"
 245         else
 246             let l = q.[highest]
 247             let next = l.First()
 248             l.Remove(next) |> ignore
 249             let value = byte highest
 250
 251             if l.Count = 0
 252             then
 253                 highest <- highest - 1
 254                 while highest > lowest && q.[highest].Count = 0 do
 255                     highest <- highest - 1
 256                 if highest = lowest
 257                 then
 258                     highest <- -1
 259                     lowest <- size
 260
 261             value, next
 262
 263     member this.NextMin () : byte * Point =
 264         if this.IsEmpty
 265         then
 266             invalidOp "Queue is empty"
 267         else
 268             let l = q.[lowest + 1]
 269             let next = l.First()
 270             l.Remove(next) |> ignore
 271             let value = byte (lowest + 1)
 272
 273             if l.Count = 0
 274             then
 275                 lowest <- lowest + 1
 276                 while lowest < highest && q.[lowest + 1].Count = 0 do
 277                     lowest <- lowest + 1
 278                 if highest = lowest
 279                 then
 280                     highest <- -1
 281                     lowest <- size
 282
 283             value, next
 284
 285     member this.Max =
 286         highest |> byte
 287
 288     member this.Min =
 289         lowest + 1 |> byte
 290
 291     member this.Add (value: byte) (p: Point) =
 292         let vi = int value
 293
 294         if vi > highest
 295         then
 296             highest <- vi
 297         if vi <= lowest
 298         then
 299             lowest <- vi - 1
 300
 301         q.[vi].Add(p) |> ignore
 302
 303     member this.Remove (value: byte) (p: Point) =
 304         let vi = int value
 305         if q.[vi].Remove(p) && q.[vi].Count = 0
 306         then
 307             if vi = highest
 308             then
 309                 highest <- highest - 1
 310                 while highest > lowest && q.[highest].Count = 0 do
 311                     highest <- highest - 1
 312             elif vi - 1 = lowest
 313             then
 314                 lowest <- lowest + 1
 315                 while lowest < highest && q.[lowest + 1].Count = 0 do
 316                     lowest <- lowest + 1
 317
 318             if highest = lowest // The queue is now empty.
 319             then
 320                 highest <- -1
 321                 lowest <- size
 322
 323     member this.IsEmpty =
 324         highest = -1
 325
 326     member this.Clear () =
 327         while highest > lowest  do
 328             q.[highest].Clear()
 329             highest <- highest - 1
 330         highest <- -1
 331         lowest <- size
 332
 333
 334 type private AreaState =
 335     | Removed = 1
 336     | Unprocessed = 2
 337     | Validated = 3
 338
 339 type private AreaOperation =
 340     | Opening = 1
 341     | Closing = 2
 342
 343 [<AllowNullLiteral>]
 344 type private Area (elements: Points) =
 345     member this.Elements = elements
 346     member val Intensity = None with get, set
 347     member val State = AreaState.Unprocessed with get, set
 348
 349 let private areaOperation (img: Image<Gray, byte>) (area: int) (op: AreaOperation) =
 350     let w = img.Width
 351     let h = img.Height
 352     let imgData = img.Data
 353     let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
 354
 355     let areas = List<Area>((if op = AreaOperation.Opening then findMaxima img else findMinima img) |> Seq.map Area)
 356
 357     let pixels: Area[,] = Array2D.create h w null
 358     for m in areas do
 359         for e in m.Elements do
 360             pixels.[e.Y, e.X] <- m
 361
 362     let queue = PriorityQueue()
 363
 364     let addEdgeToQueue (elements: Points) =
 365         for p in elements do
 366             for i, j in se do
 367                 let ni = i + p.Y
 368                 let nj = j + p.X
 369                 let p' = Point(nj, ni)
 370                 if ni >= 0 && ni < h && nj >= 0 && nj < w && not (elements.Contains(p'))
 371                 then
 372                     queue.Add (imgData.[ni, nj, 0]) p'
 373
 374     // Reverse order is quicker.
 375     for i in areas.Count - 1 .. -1 .. 0 do
 376         let m = areas.[i]
 377         if m.Elements.Count <= area && m.State <> AreaState.Removed
 378         then
 379             queue.Clear()
 380             addEdgeToQueue m.Elements
 381
 382             let mutable intensity = if op = AreaOperation.Opening then queue.Max else queue.Min
 383             let nextElements = Points()
 384
 385             let mutable stop = false
 386             while not stop do
 387                 let intensity', p = if op = AreaOperation.Opening then queue.NextMax () else queue.NextMin ()
 388                 let mutable merged = false
 389
 390                 if intensity' = intensity // The intensity doesn't change.
 391                 then
 392                     if m.Elements.Count + nextElements.Count + 1 > area
 393                     then
 394                         m.State <- AreaState.Validated
 395                         m.Intensity <- Some intensity
 396                         stop <- true
 397                     else
 398                         nextElements.Add(p) |> ignore
 399
 400                 elif if op = AreaOperation.Opening then intensity' < intensity else intensity' > intensity
 401                 then
 402                     m.Elements.UnionWith(nextElements)
 403                     for e in nextElements do
 404                         pixels.[e.Y, e.X] <- m
 405
 406                     if m.Elements.Count = area
 407                     then
 408                         m.State <- AreaState.Validated
 409                         m.Intensity <- Some (intensity')
 410                         stop <- true
 411                     else
 412                         intensity <- intensity'
 413                         nextElements.Clear()
 414                         nextElements.Add(p) |> ignore
 415
 416                 else
 417                     let m' = pixels.[p.Y, p.X]
 418                     if m' <> null
 419                     then
 420                         if m'.Elements.Count + m.Elements.Count <= area
 421                         then
 422                             m'.State <- AreaState.Removed
 423                             for e in m'.Elements do
 424                                 pixels.[e.Y, e.X] <- m
 425                                 queue.Remove imgData.[e.Y, e.X, 0] e
 426                             addEdgeToQueue m'.Elements
 427                             m.Elements.UnionWith(m'.Elements)
 428                             let intensityMax = if op = AreaOperation.Opening then queue.Max else queue.Min
 429                             if intensityMax <> intensity
 430                             then
 431                                 intensity <- intensityMax
 432                                 nextElements.Clear()
 433                             merged <- true
 434
 435                     if not merged
 436                     then
 437                         m.State <- AreaState.Validated
 438                         m.Intensity <- Some (intensity)
 439                         stop <- true
 440
 441                 if not stop && not merged
 442                 then
 443                     for i, j in se do
 444                         let ni = i + p.Y
 445                         let nj = j + p.X
 446                         let p' = Point(nj, ni)
 447                         if ni < 0 || ni >= h || nj < 0 || nj >= w
 448                         then
 449                             m.State <- AreaState.Validated
 450                             m.Intensity <- Some (intensity)
 451                             stop <- true
 452                         elif not (m.Elements.Contains(p')) && not (nextElements.Contains(p'))
 453                         then
 454                             queue.Add (imgData.[ni, nj, 0]) p'
 455
 456                 if queue.IsEmpty
 457                 then
 458                     if m.Elements.Count + nextElements.Count <= area
 459                     then
 460                         m.State <- AreaState.Validated
 461                         m.Intensity <- Some intensity'
 462                         m.Elements.UnionWith(nextElements)
 463                     stop <- true
 464
 465     for m in areas do
 466         if m.State = AreaState.Validated
 467         then
 468             match m.Intensity with
 469             | Some i ->
 470                 for p in m.Elements do
 471                     imgData.[p.Y, p.X, 0] <- i
 472             | _ -> ()
 473     ()
 474
 475
 476 let areaOpen (img: Image<Gray, byte>) (area: int) =
 477     areaOperation img area AreaOperation.Opening
 478
 479 let areaClose (img: Image<Gray, byte>) (area: int) =
 480     areaOperation img area AreaOperation.Closing
 481
 482 // A simpler algorithm than 'areaOpen' but slower.
 483 let areaOpen2 (img: Image<Gray, byte>) (area: int) =
 484     let w = img.Width
 485     let h = img.Height
 486     let imgData = img.Data
 487     let se = [| -1, 0; 0, -1; 1, 0; 0, 1 |]
 488
 489     let histogram = Array.zeroCreate 256
 490     for i in 0 .. h - 1 do
 491         for j in 0 .. w - 1 do
 492             let v = imgData.[i, j, 0] |> int
 493             histogram.[v] <- histogram.[v] + 1
 494
 495     let flooded : bool[,] = Array2D.zeroCreate h w
 496
 497     let pointsChecked = HashSet<Point>()
 498     let pointsToCheck = Stack<Point>()
 499
 500     for level in 255 .. -1 .. 0 do
 501         let mutable n = histogram.[level]
 502         if n > 0
 503         then
 504             for i in 0 .. h - 1 do
 505                 for j in 0 .. w - 1 do
 506                     if not flooded.[i, j] && imgData.[i, j, 0] = byte level
 507                     then
 508                         let mutable maxNeighborValue = 0uy
 509                         pointsChecked.Clear()
 510                         pointsToCheck.Clear()
 511                         pointsToCheck.Push(Point(j, i))
 512
 513                         while pointsToCheck.Count > 0 do
 514                             let next = pointsToCheck.Pop()
 515                             pointsChecked.Add(next) |> ignore
 516                             flooded.[next.Y, next.X] <- true
 517
 518                             for nx, ny in se do
 519                                 let p = Point(next.X + nx, next.Y + ny)
 520                                 if p.X >= 0 && p.X < w && p.Y >= 0 && p.Y < h
 521                                 then
 522                                     let v = imgData.[p.Y, p.X, 0]
 523                                     if v = byte level
 524                                     then
 525                                         if not (pointsChecked.Contains(p))
 526                                         then
 527                                             pointsToCheck.Push(p)
 528                                     elif v > maxNeighborValue
 529                                     then
 530                                         maxNeighborValue <- v
 531
 532                         if int maxNeighborValue < level && pointsChecked.Count <= area
 533                         then
 534                             for p in pointsChecked do
 535                                 imgData.[p.Y, p.X, 0] <- maxNeighborValue
 536
 537
 538 // Zhang and Suen algorithm.
 539 // Modify 'mat' in place.
 540 let thin (mat: Matrix<byte>) =
 541     let w = mat.Width
 542     let h = mat.Height
 543     let mutable data1 = mat.Data
 544     let mutable data2 = Array2D.copy data1
 545
 546     let mutable pixelChanged = true
 547     let mutable oddIteration = true
 548
 549     while pixelChanged do
 550         pixelChanged <- false
 551         for i in 0..h-1 do
 552             for j in 0..w-1 do
 553                 if data1.[i, j] = 1uy
 554                 then
 555                     let p2 = if i = 0 then 0uy else data1.[i-1, j]
 556                     let p3 = if i = 0 || j = w-1 then 0uy else data1.[i-1, j+1]
 557                     let p4 = if j = w-1 then 0uy else data1.[i, j+1]
 558                     let p5 = if i = h-1 || j = w-1 then 0uy else data1.[i+1, j+1]
 559                     let p6 = if i = h-1 then 0uy else data1.[i+1, j]
 560                     let p7 = if i = h-1 || j = 0 then 0uy else data1.[i+1, j-1]
 561                     let p8 = if j = 0 then 0uy else data1.[i, j-1]
 562                     let p9 = if i = 0 || j = 0 then 0uy else data1.[i-1, j-1]
 563
 564                     let sumNeighbors = p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9
 565                     if sumNeighbors >= 2uy && sumNeighbors <= 6uy &&
 566                         (if p2 = 0uy && p3 = 1uy then 1 else 0) +
 567                         (if p3 = 0uy && p4 = 1uy then 1 else 0) +
 568                         (if p4 = 0uy && p5 = 1uy then 1 else 0) +
 569                         (if p5 = 0uy && p6 = 1uy then 1 else 0) +
 570                         (if p6 = 0uy && p7 = 1uy then 1 else 0) +
 571                         (if p7 = 0uy && p8 = 1uy then 1 else 0) +
 572                         (if p8 = 0uy && p9 = 1uy then 1 else 0) +
 573                         (if p9 = 0uy && p2 = 1uy then 1 else 0) = 1 &&
 574                         if oddIteration
 575                         then p2 * p4 * p6 = 0uy && p4 * p6 * p8 = 0uy
 576                         else p2 * p4 * p8 = 0uy && p2 * p6 * p8 = 0uy
 577                     then
 578                         data2.[i, j] <- 0uy
 579                         pixelChanged <- true
 580                 else
 581                     data2.[i, j] <- 0uy
 582
 583         oddIteration <- not oddIteration
 584         let tmp = data1
 585         data1 <- data2
 586         data2 <- tmp
 587
 588
 589 // Remove all 8-connected pixels with an area equal or greater than 'areaSize'.
 590 // Modify 'mat' in place.
 591 let removeArea (mat: Matrix<byte>) (areaSize: int) =
 592     let neighbors = [|
 593         (-1,  0) // p2
 594         (-1,  1) // p3
 595         ( 0,  1) // p4
 596         ( 1,  1) // p5
 597         ( 1,  0) // p6
 598         ( 1, -1) // p7
 599         ( 0, -1) // p8
 600         (-1, -1) |] // p9
 601
 602     let mat' = new Matrix<byte>(mat.Size)
 603     let w = mat'.Width
 604     let h = mat'.Height
 605     mat.CopyTo(mat')
 606
 607     let data = mat.Data
 608     let data' = mat'.Data
 609
 610     for i in 0..h-1 do
 611         for j in 0..w-1 do
 612             if data'.[i, j] = 1uy
 613             then
 614                 let neighborhood = List<Point>()
 615                 let neighborsToCheck = Stack<Point>()
 616                 neighborsToCheck.Push(Point(j, i))
 617                 data'.[i, j] <- 0uy
 618
 619                 while neighborsToCheck.Count > 0 do
 620                     let n = neighborsToCheck.Pop()
 621                     neighborhood.Add(n)
 622                     for (ni, nj) in neighbors do
 623                         let pi = n.Y + ni
 624                         let pj = n.X + nj
 625                         if pi >= 0 && pi < h && pj >= 0 && pj < w && data'.[pi, pj] = 1uy
 626                         then
 627                             neighborsToCheck.Push(Point(pj, pi))
 628                             data'.[pi, pj] <- 0uy
 629                 if neighborhood.Count <= areaSize
 630                 then
 631                     for n in neighborhood do
 632                         data.[n.Y, n.X] <- 0uy
 633
 634 let connectedComponents (img: Image<Gray, byte>) (startPoints: List<Point>) : List<Point> =
 635     let w = img.Width
 636     let h = img.Height
 637
 638     let pointChecked = Points()
 639     let pointToCheck = Stack<Point>(startPoints);
 640
 641     let data = img.Data
 642
 643     while pointToCheck.Count > 0 do
 644         let next = pointToCheck.Pop()
 645         pointChecked.Add(next) |> ignore
 646         for ny in -1 .. 1 do
 647             for nx in -1 .. 1 do
 648                 if ny <> 0 && nx <> 0
 649                 then
 650                     let p = Point(next.X + nx, next.Y + ny)
 651                     if p.X >= 0 && p.X < w && p.Y >= 0 && p.Y < h && data.[p.Y, p.X, 0] > 0uy && not (pointChecked.Contains p)
 652                     then
 653                         pointToCheck.Push(p)
 654
 655     List<Point>(pointChecked)
 656
 657
 658 let drawLine (img: Image<'TColor, 'TDepth>) (color: 'TColor) (x0: int) (y0: int) (x1: int) (y1: int) (thickness: int) =
 659     img.Draw(LineSegment2D(Point(x0, y0), Point(x1, y1)), color, thickness);
 660
 661
 662 let drawLineF (img: Image<'TColor, 'TDepth>) (color: 'TColor) (x0: float) (y0: float) (x1: float) (y1: float) (thickness: int) =
 663     img.Draw(LineSegment2DF(PointF(float32 x0, float32 y0), PointF(float32 x1, float32 y1)), color, thickness, CvEnum.LineType.AntiAlias);
 664
 665
 666 let drawEllipse (img: Image<'TColor, 'TDepth>) (e: Types.Ellipse) (color: 'TColor) (alpha: float) =
 667
 668     if alpha >= 1.0
 669     then
 670         img.Draw(Ellipse(PointF(float32 e.Cx, float32 e.Cy), SizeF(2. * e.B |> float32, 2. * e.A |> float32), float32 <| e.Alpha / Math.PI * 180.), color, 1, CvEnum.LineType.AntiAlias)
 671     else
 672         let windowPosX = e.Cx - e.A - 5.0
 673         let gapX = windowPosX - (float (int windowPosX))
 674
 675         let windowPosY = e.Cy - e.A - 5.0
 676         let gapY = windowPosY - (float (int windowPosY))
 677
 678         let roi = Rectangle(int windowPosX, int windowPosY, 2. * (e.A + 5.0) |> int, 2.* (e.A + 5.0) |> int)
 679
 680         img.ROI <- roi
 681         if roi = img.ROI // We do not display ellipses touching the edges (FIXME)
 682         then
 683             use i = new Image<'TColor, 'TDepth>(img.ROI.Size)
 684             i.Draw(Ellipse(PointF(float32 <| (e.A + 5. + gapX) , float32 <| (e.A + 5. + gapY)), SizeF(2. * e.B |> float32, 2. * e.A |> float32), float32 <| e.Alpha / Math.PI * 180.), color, 1, CvEnum.LineType.AntiAlias)
 685             CvInvoke.AddWeighted(img, 1.0, i, alpha, 0.0, img)
 686         img.ROI <- Rectangle.Empty
 687
 688
 689 let drawEllipses (img: Image<'TColor, 'TDepth>) (ellipses: Types.Ellipse list) (color: 'TColor) (alpha: float) =
 690     List.iter (fun e -> drawEllipse img e color alpha) ellipses
 691
 692
 693 let rngCell =  System.Random()
 694 let drawCell (img: Image<Bgr, byte>) (drawCellContent: bool) (c: Types.Cell) =
 695     if drawCellContent
 696     then
 697         let colorB = rngCell.Next(20, 70)
 698         let colorG = rngCell.Next(20, 70)
 699         let colorR = rngCell.Next(20, 70)
 700
 701         for y in 0 .. c.elements.Height - 1 do
 702             for x in 0 .. c.elements.Width - 1 do
 703                 if c.elements.[y, x] > 0uy
 704                 then
 705                     let dx, dy = c.center.X - c.elements.Width / 2, c.center.Y - c.elements.Height / 2
 706                     let b = img.Data.[y + dy, x + dx, 0] |> int
 707                     let g = img.Data.[y + dy, x + dx, 1] |> int
 708                     let r = img.Data.[y + dy, x + dx, 2] |> int
 709                     img.Data.[y + dy, x + dx, 0] <- if b + colorB > 255 then 255uy else byte (b + colorB)
 710                     img.Data.[y + dy, x + dx, 1] <- if g + colorG > 255 then 255uy else byte (g + colorG)
 711                     img.Data.[y + dy, x + dx, 2] <- if r + colorR > 255 then 255uy else byte (r + colorR)
 712
 713     let crossColor, crossColor2 =
 714         match c.cellClass with
 715         | Types.HealthyRBC -> Bgr(255., 0., 0.), Bgr(255., 255., 255.)
 716         | Types.InfectedRBC -> Bgr(0., 0., 255.), Bgr(120., 120., 255.)
 717         | Types.Peculiar -> Bgr(0., 0., 0.), Bgr(80., 80., 80.)
 718
 719     drawLine img crossColor2 (c.center.X - 3) c.center.Y (c.center.X + 3) c.center.Y 2
 720     drawLine img crossColor2 c.center.X (c.center.Y - 3) c.center.X (c.center.Y + 3) 2
 721
 722     drawLine img crossColor (c.center.X - 3) c.center.Y (c.center.X + 3) c.center.Y 1
 723     drawLine img crossColor c.center.X (c.center.Y - 3) c.center.X (c.center.Y + 3) 1
 724
 725
 726 let drawCells (img: Image<Bgr, byte>) (drawCellContent: bool) (cells: Types.Cell list) =
 727     List.iter (fun c -> drawCell img drawCellContent c) cells