1 | /*****************************************************************************/ |
2 | // Copyright 2006 Adobe Systems Incorporated |
3 | // All Rights Reserved. |
4 | // |
5 | // NOTICE: Adobe permits you to use, modify, and distribute this file in |
6 | // accordance with the terms of the Adobe license agreement accompanying it. |
7 | /*****************************************************************************/ |
8 | |
9 | /* $Id: //mondo/dng_sdk_1_4/dng_sdk/source/dng_temperature.cpp#1 $ */ |
10 | /* $DateTime: 2012/05/30 13:28:51 $ */ |
11 | /* $Change: 832332 $ */ |
12 | /* $Author: tknoll $ */ |
13 | |
14 | #include "dng_temperature.h" |
15 | |
16 | #include "dng_xy_coord.h" |
17 | |
18 | /*****************************************************************************/ |
19 | |
20 | // Scale factor between distances in uv space to a more user friendly "tint" |
21 | // parameter. |
22 | |
23 | static const real64 kTintScale = -3000.0; |
24 | |
25 | /*****************************************************************************/ |
26 | |
27 | // Table from Wyszecki & Stiles, "Color Science", second edition, page 228. |
28 | |
29 | struct ruvt |
30 | { |
31 | real64 r; |
32 | real64 u; |
33 | real64 v; |
34 | real64 t; |
35 | }; |
36 | |
37 | static const ruvt kTempTable [] = |
38 | { |
39 | { 0, 0.18006, 0.26352, -0.24341 }, |
40 | { 10, 0.18066, 0.26589, -0.25479 }, |
41 | { 20, 0.18133, 0.26846, -0.26876 }, |
42 | { 30, 0.18208, 0.27119, -0.28539 }, |
43 | { 40, 0.18293, 0.27407, -0.30470 }, |
44 | { 50, 0.18388, 0.27709, -0.32675 }, |
45 | { 60, 0.18494, 0.28021, -0.35156 }, |
46 | { 70, 0.18611, 0.28342, -0.37915 }, |
47 | { 80, 0.18740, 0.28668, -0.40955 }, |
48 | { 90, 0.18880, 0.28997, -0.44278 }, |
49 | { 100, 0.19032, 0.29326, -0.47888 }, |
50 | { 125, 0.19462, 0.30141, -0.58204 }, |
51 | { 150, 0.19962, 0.30921, -0.70471 }, |
52 | { 175, 0.20525, 0.31647, -0.84901 }, |
53 | { 200, 0.21142, 0.32312, -1.0182 }, |
54 | { 225, 0.21807, 0.32909, -1.2168 }, |
55 | { 250, 0.22511, 0.33439, -1.4512 }, |
56 | { 275, 0.23247, 0.33904, -1.7298 }, |
57 | { 300, 0.24010, 0.34308, -2.0637 }, |
58 | { 325, 0.24702, 0.34655, -2.4681 }, |
59 | { 350, 0.25591, 0.34951, -2.9641 }, |
60 | { 375, 0.26400, 0.35200, -3.5814 }, |
61 | { 400, 0.27218, 0.35407, -4.3633 }, |
62 | { 425, 0.28039, 0.35577, -5.3762 }, |
63 | { 450, 0.28863, 0.35714, -6.7262 }, |
64 | { 475, 0.29685, 0.35823, -8.5955 }, |
65 | { 500, 0.30505, 0.35907, -11.324 }, |
66 | { 525, 0.31320, 0.35968, -15.628 }, |
67 | { 550, 0.32129, 0.36011, -23.325 }, |
68 | { 575, 0.32931, 0.36038, -40.770 }, |
69 | { 600, 0.33724, 0.36051, -116.45 } |
70 | }; |
71 | |
72 | /*****************************************************************************/ |
73 | |
74 | void dng_temperature::Set_xy_coord (const dng_xy_coord &xy) |
75 | { |
76 | |
77 | // Convert to uv space. |
78 | |
79 | real64 u = 2.0 * xy.x / (1.5 - xy.x + 6.0 * xy.y); |
80 | real64 v = 3.0 * xy.y / (1.5 - xy.x + 6.0 * xy.y); |
81 | |
82 | // Search for line pair coordinate is between. |
83 | |
84 | real64 last_dt = 0.0; |
85 | |
86 | real64 last_dv = 0.0; |
87 | real64 last_du = 0.0; |
88 | |
89 | for (uint32 index = 1; index <= 30; index++) |
90 | { |
91 | |
92 | // Convert slope to delta-u and delta-v, with length 1. |
93 | |
94 | real64 du = 1.0; |
95 | real64 dv = kTempTable [index] . t; |
96 | |
97 | real64 len = sqrt (1.0 + dv * dv); |
98 | |
99 | du /= len; |
100 | dv /= len; |
101 | |
102 | // Find delta from black body point to test coordinate. |
103 | |
104 | real64 uu = u - kTempTable [index] . u; |
105 | real64 vv = v - kTempTable [index] . v; |
106 | |
107 | // Find distance above or below line. |
108 | |
109 | real64 dt = - uu * dv + vv * du; |
110 | |
111 | // If below line, we have found line pair. |
112 | |
113 | if (dt <= 0.0 || index == 30) |
114 | { |
115 | |
116 | // Find fractional weight of two lines. |
117 | |
118 | if (dt > 0.0) |
119 | dt = 0.0; |
120 | |
121 | dt = -dt; |
122 | |
123 | real64 f; |
124 | |
125 | if (index == 1) |
126 | { |
127 | f = 0.0; |
128 | } |
129 | else |
130 | { |
131 | f = dt / (last_dt + dt); |
132 | } |
133 | |
134 | // Interpolate the temperature. |
135 | |
136 | fTemperature = 1.0E6 / (kTempTable [index - 1] . r * f + |
137 | kTempTable [index ] . r * (1.0 - f)); |
138 | |
139 | // Find delta from black body point to test coordinate. |
140 | |
141 | uu = u - (kTempTable [index - 1] . u * f + |
142 | kTempTable [index ] . u * (1.0 - f)); |
143 | |
144 | vv = v - (kTempTable [index - 1] . v * f + |
145 | kTempTable [index ] . v * (1.0 - f)); |
146 | |
147 | // Interpolate vectors along slope. |
148 | |
149 | du = du * (1.0 - f) + last_du * f; |
150 | dv = dv * (1.0 - f) + last_dv * f; |
151 | |
152 | len = sqrt (du * du + dv * dv); |
153 | |
154 | du /= len; |
155 | dv /= len; |
156 | |
157 | // Find distance along slope. |
158 | |
159 | fTint = (uu * du + vv * dv) * kTintScale; |
160 | |
161 | break; |
162 | |
163 | } |
164 | |
165 | // Try next line pair. |
166 | |
167 | last_dt = dt; |
168 | |
169 | last_du = du; |
170 | last_dv = dv; |
171 | |
172 | } |
173 | |
174 | } |
175 | |
176 | /*****************************************************************************/ |
177 | |
178 | dng_xy_coord dng_temperature::Get_xy_coord () const |
179 | { |
180 | |
181 | dng_xy_coord result; |
182 | |
183 | // Find inverse temperature to use as index. |
184 | |
185 | real64 r = 1.0E6 / fTemperature; |
186 | |
187 | // Convert tint to offset is uv space. |
188 | |
189 | real64 offset = fTint * (1.0 / kTintScale); |
190 | |
191 | // Search for line pair containing coordinate. |
192 | |
193 | for (uint32 index = 0; index <= 29; index++) |
194 | { |
195 | |
196 | if (r < kTempTable [index + 1] . r || index == 29) |
197 | { |
198 | |
199 | // Find relative weight of first line. |
200 | |
201 | real64 f = (kTempTable [index + 1] . r - r) / |
202 | (kTempTable [index + 1] . r - kTempTable [index] . r); |
203 | |
204 | // Interpolate the black body coordinates. |
205 | |
206 | real64 u = kTempTable [index ] . u * f + |
207 | kTempTable [index + 1] . u * (1.0 - f); |
208 | |
209 | real64 v = kTempTable [index ] . v * f + |
210 | kTempTable [index + 1] . v * (1.0 - f); |
211 | |
212 | // Find vectors along slope for each line. |
213 | |
214 | real64 uu1 = 1.0; |
215 | real64 vv1 = kTempTable [index] . t; |
216 | |
217 | real64 uu2 = 1.0; |
218 | real64 vv2 = kTempTable [index + 1] . t; |
219 | |
220 | real64 len1 = sqrt (1.0 + vv1 * vv1); |
221 | real64 len2 = sqrt (1.0 + vv2 * vv2); |
222 | |
223 | uu1 /= len1; |
224 | vv1 /= len1; |
225 | |
226 | uu2 /= len2; |
227 | vv2 /= len2; |
228 | |
229 | // Find vector from black body point. |
230 | |
231 | real64 uu3 = uu1 * f + uu2 * (1.0 - f); |
232 | real64 vv3 = vv1 * f + vv2 * (1.0 - f); |
233 | |
234 | real64 len3 = sqrt (uu3 * uu3 + vv3 * vv3); |
235 | |
236 | uu3 /= len3; |
237 | vv3 /= len3; |
238 | |
239 | // Adjust coordinate along this vector. |
240 | |
241 | u += uu3 * offset; |
242 | v += vv3 * offset; |
243 | |
244 | // Convert to xy coordinates. |
245 | |
246 | result.x = 1.5 * u / (u - 4.0 * v + 2.0); |
247 | result.y = v / (u - 4.0 * v + 2.0); |
248 | |
249 | break; |
250 | |
251 | } |
252 | |
253 | } |
254 | |
255 | return result; |
256 | |
257 | } |
258 | |
259 | /*****************************************************************************/ |
260 | |