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fa85bb6f JFM |
1 | /* |
2 | * Functions for auto gain. | |
3 | * | |
4 | * Copyright (C) 2010-2011 Hans de Goede <hdegoede@redhat.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | */ | |
20 | ||
a648e310 | 21 | #ifdef WANT_REGULAR_AUTOGAIN |
fa85bb6f JFM |
22 | /* auto gain and exposure algorithm based on the knee algorithm described here: |
23 | http://ytse.tricolour.net/docs/LowLightOptimization.html | |
24 | ||
25 | Returns 0 if no changes were made, 1 if the gain and or exposure settings | |
26 | where changed. */ | |
27 | static inline int auto_gain_n_exposure( | |
28 | struct gspca_dev *gspca_dev, | |
29 | int avg_lum, | |
30 | int desired_avg_lum, | |
31 | int deadzone, | |
32 | int gain_knee, | |
33 | int exposure_knee) | |
34 | { | |
35 | struct sd *sd = (struct sd *) gspca_dev; | |
36 | int i, steps, gain, orig_gain, exposure, orig_exposure; | |
37 | int retval = 0; | |
38 | ||
39 | orig_gain = gain = sd->ctrls[GAIN].val; | |
40 | orig_exposure = exposure = sd->ctrls[EXPOSURE].val; | |
41 | ||
42 | /* If we are of a multiple of deadzone, do multiple steps to reach the | |
43 | desired lumination fast (with the risc of a slight overshoot) */ | |
44 | steps = abs(desired_avg_lum - avg_lum) / deadzone; | |
45 | ||
46 | PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d", | |
47 | avg_lum, desired_avg_lum, steps); | |
48 | ||
49 | for (i = 0; i < steps; i++) { | |
50 | if (avg_lum > desired_avg_lum) { | |
51 | if (gain > gain_knee) | |
52 | gain--; | |
53 | else if (exposure > exposure_knee) | |
54 | exposure--; | |
55 | else if (gain > sd->ctrls[GAIN].def) | |
56 | gain--; | |
57 | else if (exposure > sd->ctrls[EXPOSURE].min) | |
58 | exposure--; | |
59 | else if (gain > sd->ctrls[GAIN].min) | |
60 | gain--; | |
61 | else | |
62 | break; | |
63 | } else { | |
64 | if (gain < sd->ctrls[GAIN].def) | |
65 | gain++; | |
66 | else if (exposure < exposure_knee) | |
67 | exposure++; | |
68 | else if (gain < gain_knee) | |
69 | gain++; | |
70 | else if (exposure < sd->ctrls[EXPOSURE].max) | |
71 | exposure++; | |
72 | else if (gain < sd->ctrls[GAIN].max) | |
73 | gain++; | |
74 | else | |
75 | break; | |
76 | } | |
77 | } | |
78 | ||
79 | if (gain != orig_gain) { | |
80 | sd->ctrls[GAIN].val = gain; | |
81 | setgain(gspca_dev); | |
82 | retval = 1; | |
83 | } | |
84 | if (exposure != orig_exposure) { | |
85 | sd->ctrls[EXPOSURE].val = exposure; | |
86 | setexposure(gspca_dev); | |
87 | retval = 1; | |
88 | } | |
89 | ||
90 | if (retval) | |
91 | PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d", | |
92 | gain, exposure); | |
93 | return retval; | |
94 | } | |
a648e310 | 95 | #endif |
fa85bb6f | 96 | |
a648e310 | 97 | #ifdef WANT_COARSE_EXPO_AUTOGAIN |
fa85bb6f JFM |
98 | /* Autogain + exposure algorithm for cameras with a coarse exposure control |
99 | (usually this means we can only control the clockdiv to change exposure) | |
100 | As changing the clockdiv so that the fps drops from 30 to 15 fps for | |
101 | example, will lead to a huge exposure change (it effectively doubles), | |
102 | this algorithm normally tries to only adjust the gain (between 40 and | |
103 | 80 %) and if that does not help, only then changes exposure. This leads | |
104 | to a much more stable image then using the knee algorithm which at | |
105 | certain points of the knee graph will only try to adjust exposure, | |
106 | which leads to oscilating as one exposure step is huge. | |
107 | ||
108 | Note this assumes that the sd struct for the cam in question has | |
a648e310 | 109 | exp_too_low_cnt and exp_too_high_cnt int members for use by this function. |
fa85bb6f JFM |
110 | |
111 | Returns 0 if no changes were made, 1 if the gain and or exposure settings | |
112 | where changed. */ | |
113 | static inline int coarse_grained_expo_autogain( | |
114 | struct gspca_dev *gspca_dev, | |
115 | int avg_lum, | |
116 | int desired_avg_lum, | |
117 | int deadzone) | |
118 | { | |
119 | struct sd *sd = (struct sd *) gspca_dev; | |
120 | int steps, gain, orig_gain, exposure, orig_exposure; | |
121 | int gain_low, gain_high; | |
122 | int retval = 0; | |
123 | ||
124 | orig_gain = gain = sd->ctrls[GAIN].val; | |
125 | orig_exposure = exposure = sd->ctrls[EXPOSURE].val; | |
126 | ||
127 | gain_low = (sd->ctrls[GAIN].max - sd->ctrls[GAIN].min) / 5 * 2; | |
128 | gain_low += sd->ctrls[GAIN].min; | |
129 | gain_high = (sd->ctrls[GAIN].max - sd->ctrls[GAIN].min) / 5 * 4; | |
130 | gain_high += sd->ctrls[GAIN].min; | |
131 | ||
132 | /* If we are of a multiple of deadzone, do multiple steps to reach the | |
133 | desired lumination fast (with the risc of a slight overshoot) */ | |
134 | steps = (desired_avg_lum - avg_lum) / deadzone; | |
135 | ||
136 | PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d", | |
137 | avg_lum, desired_avg_lum, steps); | |
138 | ||
139 | if ((gain + steps) > gain_high && | |
140 | exposure < sd->ctrls[EXPOSURE].max) { | |
141 | gain = gain_high; | |
142 | sd->exp_too_low_cnt++; | |
143 | sd->exp_too_high_cnt = 0; | |
144 | } else if ((gain + steps) < gain_low && | |
145 | exposure > sd->ctrls[EXPOSURE].min) { | |
146 | gain = gain_low; | |
147 | sd->exp_too_high_cnt++; | |
148 | sd->exp_too_low_cnt = 0; | |
149 | } else { | |
150 | gain += steps; | |
151 | if (gain > sd->ctrls[GAIN].max) | |
152 | gain = sd->ctrls[GAIN].max; | |
153 | else if (gain < sd->ctrls[GAIN].min) | |
154 | gain = sd->ctrls[GAIN].min; | |
155 | sd->exp_too_high_cnt = 0; | |
156 | sd->exp_too_low_cnt = 0; | |
157 | } | |
158 | ||
159 | if (sd->exp_too_high_cnt > 3) { | |
160 | exposure--; | |
161 | sd->exp_too_high_cnt = 0; | |
162 | } else if (sd->exp_too_low_cnt > 3) { | |
163 | exposure++; | |
164 | sd->exp_too_low_cnt = 0; | |
165 | } | |
166 | ||
167 | if (gain != orig_gain) { | |
168 | sd->ctrls[GAIN].val = gain; | |
169 | setgain(gspca_dev); | |
170 | retval = 1; | |
171 | } | |
172 | if (exposure != orig_exposure) { | |
173 | sd->ctrls[EXPOSURE].val = exposure; | |
174 | setexposure(gspca_dev); | |
175 | retval = 1; | |
176 | } | |
177 | ||
178 | if (retval) | |
179 | PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d", | |
180 | gain, exposure); | |
181 | return retval; | |
182 | } | |
a648e310 | 183 | #endif |