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yaml --- r: 181751 b: refs/heads/master c: 26984b0 h: refs/heads/master i: 181749: e3496bd 181747: 156fcfe 181743: eeb9605 v: v3
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Hans de Goede
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Mauro Carvalho Chehab
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Feb 26, 2010
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| --- | ||
| refs/heads/master: 4efcfa0af11d75fa6311ef62180eefcd654be3c1 | ||
| refs/heads/master: 26984b09952d01afabaa38e747fbee083dde0374 |
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| /* | ||
| * Auto gain algorithm for camera's with a coarse exposure control | ||
| * | ||
| * Copyright (C) 2010 Hans de Goede <hdegoede@redhat.com> | ||
| * | ||
| * This program is free software; you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
| * the Free Software Foundation; either version 2 of the License, or | ||
| * (at your option) any later version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program; if not, write to the Free Software | ||
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
| */ | ||
|
|
||
| /* 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 oscilating as one exposure step is huge. | ||
| Note this assumes that the sd struct for the cam in question has | ||
| exp_too_high_cnt and exp_too_high_cnt int members for use by this function. | ||
| Returns 0 if no changes were made, 1 if the gain and or exposure settings | ||
| where changed. */ | ||
| static int gspca_coarse_grained_expo_autogain(struct gspca_dev *gspca_dev, | ||
| int avg_lum, int desired_avg_lum, int deadzone) | ||
| { | ||
| int i, steps, gain, orig_gain, exposure, orig_exposure; | ||
| int gain_low, gain_high; | ||
| const struct ctrl *gain_ctrl = NULL; | ||
| const struct ctrl *exposure_ctrl = NULL; | ||
| struct sd *sd = (struct sd *) gspca_dev; | ||
| int retval = 0; | ||
|
|
||
| for (i = 0; i < gspca_dev->sd_desc->nctrls; i++) { | ||
| if (gspca_dev->ctrl_dis & (1 << i)) | ||
| continue; | ||
| if (gspca_dev->sd_desc->ctrls[i].qctrl.id == V4L2_CID_GAIN) | ||
| gain_ctrl = &gspca_dev->sd_desc->ctrls[i]; | ||
| if (gspca_dev->sd_desc->ctrls[i].qctrl.id == V4L2_CID_EXPOSURE) | ||
| exposure_ctrl = &gspca_dev->sd_desc->ctrls[i]; | ||
| } | ||
| if (!gain_ctrl || !exposure_ctrl) { | ||
| PDEBUG(D_ERR, "Error: gspca_coarse_grained_expo_autogain " | ||
| "called on cam without gain or exposure"); | ||
| return 0; | ||
| } | ||
|
|
||
| if (gain_ctrl->get(gspca_dev, &gain) || | ||
| exposure_ctrl->get(gspca_dev, &exposure)) | ||
| return 0; | ||
|
|
||
| orig_gain = gain; | ||
| orig_exposure = exposure; | ||
| gain_low = | ||
| (gain_ctrl->qctrl.maximum - gain_ctrl->qctrl.minimum) / 5 * 2; | ||
| gain_low += gain_ctrl->qctrl.minimum; | ||
| gain_high = | ||
| (gain_ctrl->qctrl.maximum - gain_ctrl->qctrl.minimum) / 5 * 4; | ||
| gain_high += gain_ctrl->qctrl.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; | ||
|
|
||
| PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d", | ||
| avg_lum, desired_avg_lum, steps); | ||
|
|
||
| if ((gain + steps) > gain_high && | ||
| sd->exposure < exposure_ctrl->qctrl.maximum) { | ||
| gain = gain_high; | ||
| sd->exp_too_low_cnt++; | ||
| } else if ((gain + steps) < gain_low && | ||
| sd->exposure > exposure_ctrl->qctrl.minimum) { | ||
| gain = gain_low; | ||
| sd->exp_too_high_cnt++; | ||
| } else { | ||
| gain += steps; | ||
| if (gain > gain_ctrl->qctrl.maximum) | ||
| gain = gain_ctrl->qctrl.maximum; | ||
| else if (gain < gain_ctrl->qctrl.minimum) | ||
| gain = gain_ctrl->qctrl.minimum; | ||
| sd->exp_too_high_cnt = 0; | ||
| sd->exp_too_low_cnt = 0; | ||
| } | ||
|
|
||
| if (sd->exp_too_high_cnt > 3) { | ||
| exposure--; | ||
| sd->exp_too_high_cnt = 0; | ||
| } else if (sd->exp_too_low_cnt > 3) { | ||
| exposure++; | ||
| sd->exp_too_low_cnt = 0; | ||
| } | ||
|
|
||
| if (gain != orig_gain) { | ||
| gain_ctrl->set(gspca_dev, gain); | ||
| retval = 1; | ||
| } | ||
| if (exposure != orig_exposure) { | ||
| exposure_ctrl->set(gspca_dev, exposure); | ||
| retval = 1; | ||
| } | ||
|
|
||
| return retval; | ||
| } |
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