nx_img_threshold_gate.nx source
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1// nx_img_threshold_gate.nx -- proves R2 (Otsu threshold + binarize) on hand-computed images:
2// A = bimodal [50 x3, 200 x3] -> Otsu picks 50, binarize -> 3 ink pixels
3// B = two clusters [10,20,30 | 220,230,240] -> Otsu picks 30 (splits dark from light)
4// Exit 0 iff all pass. license_tier: ORIGINAL
5import "nx_gate.nx"
6import "nx_img_threshold.nx"
7
8func chk(name: *u8, got: i64, want: i64, st: *i64) -> i64 {
9 if got == want { st[0] = st[0] + 1; gw(" PASS " as *u8); gw(name); gw("\n" as *u8) }
10 else { st[1] = st[1] + 1; gw(" FAIL " as *u8); gw(name); gw(" got=" as *u8); gn(got); gw(" want=" as *u8); gn(want); gw("\n" as *u8) }
11 return 0
12}
13
14func decode(src: *u8, pix: *u8, cap: i64, dims: *i64) -> i64 {
15 var len: i64 = 0; while src[len] != (0 as u8) { len = len + 1 }
16 return img_pgm_decode(src, len, pix, cap, dims)
17}
18
19func main() -> i64 {
20 let st: *i64 = sys_mmap(16) as *i64
21 st[0] = 0; st[1] = 0
22 let dims: *i64 = sys_mmap(64) as *i64
23
24 // -- A: bimodal 50/200 --
25 let a: *u8 = "P2\n3 2\n255\n50 50 50\n200 200 200\n" as *u8
26 let pa: *u8 = sys_mmap(1024)
27 let na: i64 = decode(a, pa, 1024, dims)
28 chk("A decoded 6 pixels" as *u8, na, 6, st)
29 chk("A Otsu threshold = 50" as *u8, thr_otsu_of(pa, na), 50, st)
30 chk("A binarize -> 3 ink pixels" as *u8, thr_binarize(pa, na, 50), 3, st)
31 chk("A ink pixel (0,0) = 0" as *u8, img_get(pa, 3, 0, 0), 0, st)
32 chk("A paper pixel (2,1) = 255" as *u8, img_get(pa, 3, 2, 1), 255, st)
33
34 // -- B: two clusters (dark ~20, light ~230) --
35 let b: *u8 = "P2\n3 2\n255\n10 20 30\n220 230 240\n" as *u8
36 let pb: *u8 = sys_mmap(1024)
37 let nb: i64 = decode(b, pb, 1024, dims)
38 chk("B decoded 6 pixels" as *u8, nb, 6, st)
39 chk("B Otsu threshold = 30 (splits dark from light)" as *u8, thr_otsu_of(pb, nb), 30, st)
40 chk("B binarize -> 3 ink pixels (the dark cluster)" as *u8, thr_binarize(pb, nb, thr_otsu_of(pb, nb)), 3, st)
41
42 gw("nx_img_threshold_gate: PASS=" as *u8); gn(st[0]); gw(" FAIL=" as *u8); gn(st[1]); gw("\n" as *u8)
43 if st[1] == 0 { gw("R2 nx_img_threshold: GREEN (Otsu binarization, integer-exact)\n" as *u8); return 0 }
44 gw("R2 nx_img_threshold: RED\n" as *u8)
45 return 1
46}