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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 | // SPDX-License-Identifier: GPL-2.0-or-later /* * Functions for auto gain. * * Copyright (C) 2010-2012 Hans de Goede <hdegoede@redhat.com> */ #include "gspca.h" /* auto gain and exposure algorithm based on the knee algorithm described here: http://ytse.tricolour.net/docs/LowLightOptimization.html Returns 0 if no changes were made, 1 if the gain and or exposure settings where changed. */ int gspca_expo_autogain( struct gspca_dev *gspca_dev, int avg_lum, int desired_avg_lum, int deadzone, int gain_knee, int exposure_knee) { s32 gain, orig_gain, exposure, orig_exposure; int i, steps, retval = 0; if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0) return 0; orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain); orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure); /* If we are of a multiple of deadzone, do multiple steps to reach the desired lumination fast (with the risc of a slight overshoot) */ steps = abs(desired_avg_lum - avg_lum) / deadzone; gspca_dbg(gspca_dev, D_FRAM, "autogain: lum: %d, desired: %d, steps: %d\n", avg_lum, desired_avg_lum, steps); for (i = 0; i < steps; i++) { if (avg_lum > desired_avg_lum) { if (gain > gain_knee) gain--; else if (exposure > exposure_knee) exposure--; else if (gain > gspca_dev->gain->default_value) gain--; else if (exposure > gspca_dev->exposure->minimum) exposure--; else if (gain > gspca_dev->gain->minimum) gain--; else break; } else { if (gain < gspca_dev->gain->default_value) gain++; else if (exposure < exposure_knee) exposure++; else if (gain < gain_knee) gain++; else if (exposure < gspca_dev->exposure->maximum) exposure++; else if (gain < gspca_dev->gain->maximum) gain++; else break; } } if (gain != orig_gain) { v4l2_ctrl_s_ctrl(gspca_dev->gain, gain); retval = 1; } if (exposure != orig_exposure) { v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure); retval = 1; } if (retval) gspca_dbg(gspca_dev, D_FRAM, "autogain: changed gain: %d, expo: %d\n", gain, exposure); return retval; } EXPORT_SYMBOL(gspca_expo_autogain); /* Autogain + exposure algorithm for cameras with a coarse exposure control (usually this means we can only control the clockdiv to change exposure) As changing the clockdiv so that the fps drops from 30 to 15 fps for example, will lead to a huge exposure change (it effectively doubles), this algorithm normally tries to only adjust the gain (between 40 and 80 %) and if that does not help, only then changes exposure. This leads to a much more stable image then using the knee algorithm which at certain points of the knee graph will only try to adjust exposure, which leads to oscillating as one exposure step is huge. Returns 0 if no changes were made, 1 if the gain and or exposure settings where changed. */ int gspca_coarse_grained_expo_autogain( struct gspca_dev *gspca_dev, int avg_lum, int desired_avg_lum, int deadzone) { s32 gain_low, gain_high, gain, orig_gain, exposure, orig_exposure; int steps, retval = 0; if (v4l2_ctrl_g_ctrl(gspca_dev->autogain) == 0) return 0; orig_gain = gain = v4l2_ctrl_g_ctrl(gspca_dev->gain); orig_exposure = exposure = v4l2_ctrl_g_ctrl(gspca_dev->exposure); gain_low = (s32)(gspca_dev->gain->maximum - gspca_dev->gain->minimum) / 5 * 2 + gspca_dev->gain->minimum; gain_high = (s32)(gspca_dev->gain->maximum - gspca_dev->gain->minimum) / 5 * 4 + gspca_dev->gain->minimum; /* If we are of a multiple of deadzone, do multiple steps to reach the desired lumination fast (with the risc of a slight overshoot) */ steps = (desired_avg_lum - avg_lum) / deadzone; gspca_dbg(gspca_dev, D_FRAM, "autogain: lum: %d, desired: %d, steps: %d\n", avg_lum, desired_avg_lum, steps); if ((gain + steps) > gain_high && exposure < gspca_dev->exposure->maximum) { gain = gain_high; gspca_dev->exp_too_low_cnt++; gspca_dev->exp_too_high_cnt = 0; } else if ((gain + steps) < gain_low && exposure > gspca_dev->exposure->minimum) { gain = gain_low; gspca_dev->exp_too_high_cnt++; gspca_dev->exp_too_low_cnt = 0; } else { gain += steps; if (gain > gspca_dev->gain->maximum) gain = gspca_dev->gain->maximum; else if (gain < gspca_dev->gain->minimum) gain = gspca_dev->gain->minimum; gspca_dev->exp_too_high_cnt = 0; gspca_dev->exp_too_low_cnt = 0; } if (gspca_dev->exp_too_high_cnt > 3) { exposure--; gspca_dev->exp_too_high_cnt = 0; } else if (gspca_dev->exp_too_low_cnt > 3) { exposure++; gspca_dev->exp_too_low_cnt = 0; } if (gain != orig_gain) { v4l2_ctrl_s_ctrl(gspca_dev->gain, gain); retval = 1; } if (exposure != orig_exposure) { v4l2_ctrl_s_ctrl(gspca_dev->exposure, exposure); retval = 1; } if (retval) gspca_dbg(gspca_dev, D_FRAM, "autogain: changed gain: %d, expo: %d\n", gain, exposure); return retval; } EXPORT_SYMBOL(gspca_coarse_grained_expo_autogain); |