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
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
|
// Copyright (C) 2020 Julien Bardagi <julien.bardagi@gmail.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Reference used for implementation: https://en.wikipedia.org/wiki/HSL_and_HSV
// Since the standard 'clamp' feature is still considered unstable, we provide
// a subsititute implementaion here so we can still build with the stable toolchain.
// Source: https://github.com/rust-lang/rust/issues/44095#issuecomment-624879262
pub trait Clamp: Sized {
fn clamp<L, U>(self, lower: L, upper: U) -> Self
where
L: Into<Option<Self>>,
U: Into<Option<Self>>;
}
impl Clamp for f32 {
fn clamp<L, U>(self, lower: L, upper: U) -> Self
where
L: Into<Option<Self>>,
U: Into<Option<Self>>,
{
let below = match lower.into() {
None => self,
Some(lower) => self.max(lower),
};
match upper.into() {
None => below,
Some(upper) => below.min(upper),
}
}
}
const EPSILON: f32 = 0.00001;
// Converts a RGB pixel to HSV
#[inline]
pub fn from_rgb(in_p: &[u8; 3]) -> [f32; 3] {
let r = in_p[0] as f32 / 255.0;
let g = in_p[1] as f32 / 255.0;
let b = in_p[2] as f32 / 255.0;
let value: f32 = *in_p
.iter()
.max()
.expect("Cannot find max value from rgb input") as f32
/ 255.0;
let chroma: f32 = value
- (*in_p
.iter()
.min()
.expect("Cannot find min value from rgb input") as f32
/ 255.0);
let mut hue: f32 = if chroma == 0.0 {
0.0
} else if (value - r).abs() < EPSILON {
60.0 * ((g - b) / chroma)
} else if (value - g).abs() < EPSILON {
60.0 * (2.0 + ((b - r) / chroma))
} else if (value - b).abs() < EPSILON {
60.0 * (4.0 + ((r - g) / chroma))
} else {
0.0
};
if hue < 0.0 {
hue += 360.0;
}
let saturation: f32 = if value == 0.0 { 0.0 } else { chroma / value };
[
hue % 360.0,
saturation.clamp(0.0, 1.0),
value.clamp(0.0, 1.0),
]
}
// Converts a BGR pixel to HSV
#[inline]
pub fn from_bgr(in_p: &[u8; 3]) -> [f32; 3] {
let b = in_p[0] as f32 / 255.0;
let g = in_p[1] as f32 / 255.0;
let r = in_p[2] as f32 / 255.0;
let value: f32 = *in_p
.iter()
.max()
.expect("Cannot find max value from rgb input") as f32
/ 255.0;
let chroma: f32 = value
- (*in_p
.iter()
.min()
.expect("Cannot find min value from rgb input") as f32
/ 255.0);
let mut hue: f32 = if chroma == 0.0 {
0.0
} else if (value - r).abs() < EPSILON {
60.0 * ((g - b) / chroma)
} else if (value - g).abs() < EPSILON {
60.0 * (2.0 + ((b - r) / chroma))
} else if (value - b).abs() < EPSILON {
60.0 * (4.0 + ((r - g) / chroma))
} else {
0.0
};
if hue < 0.0 {
hue += 360.0;
}
let saturation: f32 = if value == 0.0 { 0.0 } else { chroma / value };
[
hue % 360.0,
saturation.clamp(0.0, 1.0),
value.clamp(0.0, 1.0),
]
}
// Converts a HSV pixel to RGB
#[inline]
pub fn to_rgb(in_p: &[f32; 3]) -> [u8; 3] {
let c: f32 = in_p[2] * in_p[1];
let hue_prime: f32 = in_p[0] / 60.0;
let x: f32 = c * (1.0 - ((hue_prime % 2.0) - 1.0).abs());
let rgb_prime = if hue_prime < 0.0 {
[0.0, 0.0, 0.0]
} else if hue_prime <= 1.0 {
[c, x, 0.0]
} else if hue_prime <= 2.0 {
[x, c, 0.0]
} else if hue_prime <= 3.0 {
[0.0, c, x]
} else if hue_prime <= 4.0 {
[0.0, x, c]
} else if hue_prime <= 5.0 {
[x, 0.0, c]
} else if hue_prime <= 6.0 {
[c, 0.0, x]
} else {
[0.0, 0.0, 0.0]
};
let m = in_p[2] - c;
[
((rgb_prime[0] + m) * 255.0).clamp(0.0, 255.0) as u8,
((rgb_prime[1] + m) * 255.0).clamp(0.0, 255.0) as u8,
((rgb_prime[2] + m) * 255.0).clamp(0.0, 255.0) as u8,
]
}
// Converts a HSV pixel to RGB
#[inline]
pub fn to_bgr(in_p: &[f32; 3]) -> [u8; 3] {
let c: f32 = in_p[2] * in_p[1];
let hue_prime: f32 = in_p[0] / 60.0;
let x: f32 = c * (1.0 - ((hue_prime % 2.0) - 1.0).abs());
let rgb_prime = if hue_prime < 0.0 {
[0.0, 0.0, 0.0]
} else if hue_prime <= 1.0 {
[c, x, 0.0]
} else if hue_prime <= 2.0 {
[x, c, 0.0]
} else if hue_prime <= 3.0 {
[0.0, c, x]
} else if hue_prime <= 4.0 {
[0.0, x, c]
} else if hue_prime <= 5.0 {
[x, 0.0, c]
} else if hue_prime <= 6.0 {
[c, 0.0, x]
} else {
[0.0, 0.0, 0.0]
};
let m = in_p[2] - c;
[
((rgb_prime[2] + m) * 255.0).clamp(0.0, 255.0) as u8,
((rgb_prime[1] + m) * 255.0).clamp(0.0, 255.0) as u8,
((rgb_prime[0] + m) * 255.0).clamp(0.0, 255.0) as u8,
]
}
#[cfg(test)]
mod tests {
fn is_equivalent(hsv: &[f32; 3], expected: &[f32; 3], eps: f32) -> bool {
// We handle hue being circular here
let ref_hue_offset = 180.0 - expected[0];
let mut shifted_hue = hsv[0] + ref_hue_offset;
if shifted_hue < 0.0 {
shifted_hue += 360.0;
}
shifted_hue %= 360.0;
(shifted_hue - 180.0).abs() < eps
&& (hsv[1] - expected[1]).abs() < eps
&& (hsv[2] - expected[2]).abs() < eps
}
const RGB_WHITE: [u8; 3] = [255, 255, 255];
const RGB_BLACK: [u8; 3] = [0, 0, 0];
const RGB_RED: [u8; 3] = [255, 0, 0];
const RGB_GREEN: [u8; 3] = [0, 255, 0];
const RGB_BLUE: [u8; 3] = [0, 0, 255];
const BGR_WHITE: [u8; 3] = [255, 255, 255];
const BGR_BLACK: [u8; 3] = [0, 0, 0];
const BGR_RED: [u8; 3] = [0, 0, 255];
const BGR_GREEN: [u8; 3] = [0, 255, 0];
const BGR_BLUE: [u8; 3] = [255, 0, 0];
const HSV_WHITE: [f32; 3] = [0.0, 0.0, 1.0];
const HSV_BLACK: [f32; 3] = [0.0, 0.0, 0.0];
const HSV_RED: [f32; 3] = [0.0, 1.0, 1.0];
const HSV_GREEN: [f32; 3] = [120.0, 1.0, 1.0];
const HSV_BLUE: [f32; 3] = [240.0, 1.0, 1.0];
#[test]
fn test_from_rgb() {
use super::*;
assert!(is_equivalent(&from_rgb(&RGB_WHITE), &HSV_WHITE, EPSILON));
assert!(is_equivalent(&from_rgb(&RGB_BLACK), &HSV_BLACK, EPSILON));
assert!(is_equivalent(&from_rgb(&RGB_RED), &HSV_RED, EPSILON));
assert!(is_equivalent(&from_rgb(&RGB_GREEN), &HSV_GREEN, EPSILON));
assert!(is_equivalent(&from_rgb(&RGB_BLUE), &HSV_BLUE, EPSILON));
}
#[test]
fn test_from_bgr() {
use super::*;
assert!(is_equivalent(&from_bgr(&BGR_WHITE), &HSV_WHITE, EPSILON));
assert!(is_equivalent(&from_bgr(&BGR_BLACK), &HSV_BLACK, EPSILON));
assert!(is_equivalent(&from_bgr(&BGR_RED), &HSV_RED, EPSILON));
assert!(is_equivalent(&from_bgr(&BGR_GREEN), &HSV_GREEN, EPSILON));
assert!(is_equivalent(&from_bgr(&BGR_BLUE), &HSV_BLUE, EPSILON));
}
#[test]
fn test_to_rgb() {
use super::*;
assert!(to_rgb(&HSV_WHITE) == RGB_WHITE);
assert!(to_rgb(&HSV_BLACK) == RGB_BLACK);
assert!(to_rgb(&HSV_RED) == RGB_RED);
assert!(to_rgb(&HSV_GREEN) == RGB_GREEN);
assert!(to_rgb(&HSV_BLUE) == RGB_BLUE);
}
#[test]
fn test_to_bgr() {
use super::*;
assert!(to_bgr(&HSV_WHITE) == BGR_WHITE);
assert!(to_bgr(&HSV_BLACK) == BGR_BLACK);
assert!(to_bgr(&HSV_RED) == BGR_RED);
assert!(to_bgr(&HSV_GREEN) == BGR_GREEN);
assert!(to_bgr(&HSV_BLUE) == BGR_BLUE);
}
}
|
