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8cd05842 HG |
1 | /* |
2 | * Functions for auto gain. | |
3 | * | |
4 | * Copyright (C) 2010-2012 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. | |
8cd05842 HG |
15 | */ |
16 | #include "gspca.h" | |
17 | ||
18 | /* auto gain and exposure algorithm based on the knee algorithm described here: | |
19 | http://ytse.tricolour.net/docs/LowLightOptimization.html | |
20 | ||
21 | Returns 0 if no changes were made, 1 if the gain and or exposure settings | |
22 | where changed. */ | |
23 | int gspca_expo_autogain( | |
24 | struct gspca_dev *gspca_dev, | |
25 | int avg_lum, | |
26 | int desired_avg_lum, | |
27 | int deadzone, | |
28 | int gain_knee, | |
29 | int exposure_knee) | |
30 | { | |
31 | s32 gain, orig_gain, exposure, orig_exposure; | |
32 | int i, steps, retval = 0; | |
33 | ||
34 | if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0) | |
35 | return 0; | |
36 | ||
37 | orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain); | |
38 | orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure); | |
39 | ||
40 | /* If we are of a multiple of deadzone, do multiple steps to reach the | |
41 | desired lumination fast (with the risc of a slight overshoot) */ | |
42 | steps = abs(desired_avg_lum - avg_lum) / deadzone; | |
43 | ||
44 | PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d", | |
45 | avg_lum, desired_avg_lum, steps); | |
46 | ||
47 | for (i = 0; i < steps; i++) { | |
48 | if (avg_lum > desired_avg_lum) { | |
49 | if (gain > gain_knee) | |
50 | gain--; | |
51 | else if (exposure > exposure_knee) | |
52 | exposure--; | |
53 | else if (gain > gspca_dev->gain->default_value) | |
54 | gain--; | |
55 | else if (exposure > gspca_dev->exposure->minimum) | |
56 | exposure--; | |
57 | else if (gain > gspca_dev->gain->minimum) | |
58 | gain--; | |
59 | else | |
60 | break; | |
61 | } else { | |
62 | if (gain < gspca_dev->gain->default_value) | |
63 | gain++; | |
64 | else if (exposure < exposure_knee) | |
65 | exposure++; | |
66 | else if (gain < gain_knee) | |
67 | gain++; | |
68 | else if (exposure < gspca_dev->exposure->maximum) | |
69 | exposure++; | |
70 | else if (gain < gspca_dev->gain->maximum) | |
71 | gain++; | |
72 | else | |
73 | break; | |
74 | } | |
75 | } | |
76 | ||
77 | if (gain != orig_gain) { | |
78 | v4l2_ctrl_s_ctrl(gspca_dev->gain, gain); | |
79 | retval = 1; | |
80 | } | |
81 | if (exposure != orig_exposure) { | |
82 | v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure); | |
83 | retval = 1; | |
84 | } | |
85 | ||
86 | if (retval) | |
87 | PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d", | |
88 | gain, exposure); | |
89 | return retval; | |
90 | } | |
91 | EXPORT_SYMBOL(gspca_expo_autogain); | |
92 | ||
93 | /* Autogain + exposure algorithm for cameras with a coarse exposure control | |
94 | (usually this means we can only control the clockdiv to change exposure) | |
95 | As changing the clockdiv so that the fps drops from 30 to 15 fps for | |
96 | example, will lead to a huge exposure change (it effectively doubles), | |
97 | this algorithm normally tries to only adjust the gain (between 40 and | |
98 | 80 %) and if that does not help, only then changes exposure. This leads | |
99 | to a much more stable image then using the knee algorithm which at | |
100 | certain points of the knee graph will only try to adjust exposure, | |
101 | which leads to oscilating as one exposure step is huge. | |
102 | ||
103 | Returns 0 if no changes were made, 1 if the gain and or exposure settings | |
104 | where changed. */ | |
105 | int gspca_coarse_grained_expo_autogain( | |
106 | struct gspca_dev *gspca_dev, | |
107 | int avg_lum, | |
108 | int desired_avg_lum, | |
109 | int deadzone) | |
110 | { | |
111 | s32 gain_low, gain_high, gain, orig_gain, exposure, orig_exposure; | |
112 | int steps, retval = 0; | |
113 | ||
114 | if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0) | |
115 | return 0; | |
116 | ||
117 | orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain); | |
118 | orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure); | |
119 | ||
0d5e8c43 | 120 | gain_low = (s32)(gspca_dev->gain->maximum - gspca_dev->gain->minimum) / |
8cd05842 | 121 | 5 * 2 + gspca_dev->gain->minimum; |
0d5e8c43 | 122 | gain_high = (s32)(gspca_dev->gain->maximum - gspca_dev->gain->minimum) / |
8cd05842 HG |
123 | 5 * 4 + gspca_dev->gain->minimum; |
124 | ||
125 | /* If we are of a multiple of deadzone, do multiple steps to reach the | |
126 | desired lumination fast (with the risc of a slight overshoot) */ | |
127 | steps = (desired_avg_lum - avg_lum) / deadzone; | |
128 | ||
129 | PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d", | |
130 | avg_lum, desired_avg_lum, steps); | |
131 | ||
132 | if ((gain + steps) > gain_high && | |
133 | exposure < gspca_dev->exposure->maximum) { | |
134 | gain = gain_high; | |
135 | gspca_dev->exp_too_low_cnt++; | |
136 | gspca_dev->exp_too_high_cnt = 0; | |
137 | } else if ((gain + steps) < gain_low && | |
138 | exposure > gspca_dev->exposure->minimum) { | |
139 | gain = gain_low; | |
140 | gspca_dev->exp_too_high_cnt++; | |
141 | gspca_dev->exp_too_low_cnt = 0; | |
142 | } else { | |
143 | gain += steps; | |
144 | if (gain > gspca_dev->gain->maximum) | |
145 | gain = gspca_dev->gain->maximum; | |
146 | else if (gain < gspca_dev->gain->minimum) | |
147 | gain = gspca_dev->gain->minimum; | |
148 | gspca_dev->exp_too_high_cnt = 0; | |
149 | gspca_dev->exp_too_low_cnt = 0; | |
150 | } | |
151 | ||
152 | if (gspca_dev->exp_too_high_cnt > 3) { | |
153 | exposure--; | |
154 | gspca_dev->exp_too_high_cnt = 0; | |
155 | } else if (gspca_dev->exp_too_low_cnt > 3) { | |
156 | exposure++; | |
157 | gspca_dev->exp_too_low_cnt = 0; | |
158 | } | |
159 | ||
160 | if (gain != orig_gain) { | |
161 | v4l2_ctrl_s_ctrl(gspca_dev->gain, gain); | |
162 | retval = 1; | |
163 | } | |
164 | if (exposure != orig_exposure) { | |
165 | v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure); | |
166 | retval = 1; | |
167 | } | |
168 | ||
169 | if (retval) | |
170 | PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d", | |
171 | gain, exposure); | |
172 | return retval; | |
173 | } | |
174 | EXPORT_SYMBOL(gspca_coarse_grained_expo_autogain); |