Split the module 'ImgTools' in many modules.

[master-thesis.git] / Parasitemia / ParasitemiaCore / ImgTools / Otsu.fs

diff --git a/Parasitemia/ParasitemiaCore/ImgTools/Otsu.fs b/Parasitemia/ParasitemiaCore/ImgTools/Otsu.fs
new file mode 100644 (file)
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+++ b/Parasitemia/ParasitemiaCore/ImgTools/Otsu.fs
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+module ParasitemiaCore.Otsu
+
+open Histogram
+
+let otsu (hist: Histogram) : float32 * float32 * float32 =
+    let mutable sumB = 0
+    let mutable wB = 0
+    let mutable maximum = 0.0
+    let mutable level = 0
+    let sum = hist.data |> Array.mapi (fun i v -> i * v |> float) |> Array.sum
+
+    for i in 0 .. hist.data.Length - 1 do
+        wB <- wB + hist.data.[i]
+        if wB <> 0
+        then
+            let wF = hist.total - wB
+            if wF <> 0
+            then
+                sumB <- sumB + i * hist.data.[i]
+                let mB = (float sumB) / (float wB)
+                let mF = (sum - float sumB) / (float wF)
+                let between = (float wB) * (float wF) * (mB - mF) ** 2.;
+                if between >= maximum
+                then
+                    level <- i
+                    maximum <- between
+
+    let mean1 =
+        let mutable sum = 0
+        let mutable nb = 0
+        for i in 0 .. level - 1 do
+            sum <- sum + i * hist.data.[i]
+            nb <- nb + hist.data.[i]
+        (sum + level * hist.data.[level] / 2) / (nb + hist.data.[level] / 2)
+
+    let mean2 =
+        let mutable sum = 0
+        let mutable nb = 0
+        for i in level + 1 .. hist.data.Length - 1 do
+            sum <- sum + i * hist.data.[i]
+            nb <- nb + hist.data.[i]
+        (sum + level * hist.data.[level] / 2) / (nb + hist.data.[level] / 2)
+
+    let toFloat l =
+        float32 l / float32 hist.data.Length * (hist.max - hist.min) + hist.min
+
+    toFloat level, toFloat mean1, toFloat mean2
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