1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
type kernel = { size : int; weights : int array; divisor : int; offset : int }
let apply (k : kernel) (img : Pixels.image) : Pixels.image =
let out = Pixels.copy img in
let half = k.size / 2 in
for y = 0 to img.height - 1 do
for x = 0 to img.width - 1 do
for c = 0 to 2 do
let sum = ref 0 in
for j = 0 to k.size - 1 do
for i = 0 to k.size - 1 do
let w = k.weights.((j * k.size) + i) in
if w <> 0 then sum := !sum + (w * Pixels.get img (x + i - half) (y + j - half) c)
done
done;
Pixels.set out x y c (Pixels.clamp ((!sum / k.divisor) + k.offset))
done
done
done;
out
let separable (weights : float array) (img : Pixels.image) : Pixels.image =
let n = Array.length weights and half = Array.length weights / 2 in
let pass (src : Pixels.image) ~(horizontal : bool) : Pixels.image =
let out = Pixels.copy src in
for y = 0 to src.height - 1 do
for x = 0 to src.width - 1 do
for c = 0 to 2 do
let sum = ref 0. in
for i = 0 to n - 1 do
let d = i - half in
let v = if horizontal then Pixels.get src (x + d) y c else Pixels.get src x (y + d) c in
sum := !sum +. (weights.(i) *. float_of_int v)
done;
Pixels.set out x y c (Pixels.clamp (int_of_float (Float.round !sum)))
done
done
done;
out
in
pass (pass img ~horizontal:true) ~horizontal:false
let blur = { size = 3; weights = Array.make 9 1; divisor = 9; offset = 0 }
let blur_more = { size = 5; weights = Array.make 25 1; divisor = 25; offset = 0 }
let sharpen = { size = 3; weights = [| 0; -1; 0; -1; 5; -1; 0; -1; 0 |]; divisor = 1; offset = 0 }
let sharpen_more = { size = 3; weights = [| -1; -1; -1; -1; 9; -1; -1; -1; -1 |]; divisor = 1; offset = 0 }
let emboss = { size = 3; weights = [| -1; -1; 0; -1; 0; 1; 0; 1; 1 |]; divisor = 1; offset = 128 }