Parasitemia/ParasitemiaCore/MatchingEllipses.fs

   1 module ParasitemiaCore.MatchingEllipses
   2
   3 open System
   4 open System.Drawing
   5 open System.Linq
   6 open System.Collections
   7 open System.Collections.Generic
   8
   9 open Types
  10 open Utils
  11
  12 type private EllipseScoreFlaggedKd (matchingScore: float32, e: Ellipse) =
  13     let mutable matchingScore = matchingScore
  14
  15     member this.Ellipse = e
  16
  17     member this.MatchingScore = matchingScore
  18
  19     member this.AddMatchingScore (score: float32) =
  20         matchingScore <- matchingScore + score
  21
  22     member val Processed = false with get, set
  23     member val Removed = false with get, set
  24
  25     interface KdTree.I2DCoords with
  26         member this.X = this.Ellipse.Cx
  27         member this.Y = this.Ellipse.Cy
  28
  29 type MatchingEllipses (radius: float32) =
  30     let ellipses = List<EllipseScoreFlaggedKd>()
  31
  32     // All ellipses with a score below this are removed.
  33     let matchingScoreThreshold = 0.4f
  34
  35     member this.Add (e: Ellipse) =
  36         ellipses.Add(EllipseScoreFlaggedKd(0.f, e))
  37
  38     member this.Ellipses : Ellipse list =
  39         List.ofSeq ellipses |> List.map (fun e -> e.Ellipse)
  40
  41     member this.PrunedEllipses : Ellipse list =
  42         if ellipses.Count = 0
  43         then
  44             []
  45         else
  46             // 1) Create a kd-tree from the ellipses list.
  47             let tree = KdTree.Tree.BuildTree (List.ofSeq ellipses)
  48
  49             // 2) Compute the matching score of each ellipses.
  50             let windowSize = radius / 3.f
  51             for e in ellipses do
  52                 e.Processed <- true
  53                 let areaE = e.Ellipse.Area
  54                 let window = { KdTree.minX = e.Ellipse.Cx - windowSize / 2.f
  55                                KdTree.maxX = e.Ellipse.Cx + windowSize / 2.f
  56                                KdTree.minY = e.Ellipse.Cy - windowSize / 2.f
  57                                KdTree.maxY = e.Ellipse.Cy + windowSize / 2.f }
  58                 for other in tree.Search window do
  59                     if not other.Processed
  60                     then
  61                         let areaOther = other.Ellipse.Area
  62                         match EEOver.EEOverlapArea e.Ellipse other.Ellipse with
  63                         | Some (overlapArea, _, _)
  64                             // Because of approximation error, see https://github.com/chraibi/EEOver/issues/4
  65                             when overlapArea - areaE < 1.f && overlapArea - areaOther < 1.f ->
  66                                 let matchingScore = (2.f * overlapArea / (areaE + areaOther)) ** 30.f
  67                                 other.AddMatchingScore(matchingScore)
  68                                 e.AddMatchingScore(matchingScore)
  69                         | _ -> ()
  70
  71             // 3) Remove ellipses whose center is near the center of another ellipse with a better score.
  72             for e in ellipses do
  73                 if e.MatchingScore < matchingScoreThreshold
  74                 then
  75                     e.Removed <- true
  76                 else
  77                     let window = { KdTree.minX = e.Ellipse.Cx - e.Ellipse.A
  78                                    KdTree.maxX = e.Ellipse.Cx + e.Ellipse.A
  79                                    KdTree.minY = e.Ellipse.Cy - e.Ellipse.A
  80                                    KdTree.maxY = e.Ellipse.Cy + e.Ellipse.A }
  81                     for other in tree.Search window do
  82                         if not other.Removed && e.MatchingScore > other.MatchingScore
  83                         then
  84                             // Case where ellipses are too close.
  85                             if distanceTwoPoints (PointF(e.Ellipse.Cx, e.Ellipse.Cy)) (PointF(other.Ellipse.Cx, other.Ellipse.Cy)) < 0.3f * e.Ellipse.B
  86                             then
  87                                 other.Removed <- true
  88                             else
  89                                 // Case where ellipses are overlapped.
  90                                 match EEOver.EEOverlapArea e.Ellipse other.Ellipse with
  91                                 | Some (overlapArea, _, _) when e.Ellipse.Area < 1.1f * overlapArea || other.Ellipse.Area < 1.1f * overlapArea ->
  92                                     other.Removed <- true
  93                                 | _ ->
  94                                     ()
  95             ellipses
  96             |> List.ofSeq
  97             |> List.filter (fun e -> not e.Removed)
  98             |> List.sortWith (fun e1 e2 -> e2.MatchingScore.CompareTo(e1.MatchingScore))
  99             |> List.map (fun e -> e.Ellipse)
 100