summaryrefslogtreecommitdiffstats
path: root/drivers/media/video/gspca/autogain_functions.h
diff options
context:
space:
mode:
authorJiri Kosina <jkosina@suse.cz>2011-04-26 10:22:15 +0200
committerJiri Kosina <jkosina@suse.cz>2011-04-26 10:22:59 +0200
commit07f9479a40cc778bc1462ada11f95b01360ae4ff (patch)
tree0676cf38df3844004bb3ebfd99dfa67a4a8998f5 /drivers/media/video/gspca/autogain_functions.h
parent9d5e6bdb3013acfb311ab407eeca0b6a6a3dedbf (diff)
parentcd2e49e90f1cae7726c9a2c54488d881d7f1cd1c (diff)
downloadlinux-stable-07f9479a40cc778bc1462ada11f95b01360ae4ff.tar.gz
linux-stable-07f9479a40cc778bc1462ada11f95b01360ae4ff.tar.bz2
linux-stable-07f9479a40cc778bc1462ada11f95b01360ae4ff.zip
Merge branch 'master' into for-next
Fast-forwarded to current state of Linus' tree as there are patches to be applied for files that didn't exist on the old branch.
Diffstat (limited to 'drivers/media/video/gspca/autogain_functions.h')
-rw-r--r--drivers/media/video/gspca/autogain_functions.h179
1 files changed, 179 insertions, 0 deletions
diff --git a/drivers/media/video/gspca/autogain_functions.h b/drivers/media/video/gspca/autogain_functions.h
new file mode 100644
index 000000000000..46777eee678b
--- /dev/null
+++ b/drivers/media/video/gspca/autogain_functions.h
@@ -0,0 +1,179 @@
+/*
+ * Functions for auto gain.
+ *
+ * Copyright (C) 2010-2011 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
+ */
+
+/* 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. */
+static inline int auto_gain_n_exposure(
+ struct gspca_dev *gspca_dev,
+ int avg_lum,
+ int desired_avg_lum,
+ int deadzone,
+ int gain_knee,
+ int exposure_knee)
+{
+ struct sd *sd = (struct sd *) gspca_dev;
+ int i, steps, gain, orig_gain, exposure, orig_exposure;
+ int retval = 0;
+
+ orig_gain = gain = sd->ctrls[GAIN].val;
+ orig_exposure = exposure = sd->ctrls[EXPOSURE].val;
+
+ /* 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;
+
+ PDEBUG(D_FRAM, "autogain: lum: %d, desired: %d, steps: %d",
+ 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 > sd->ctrls[GAIN].def)
+ gain--;
+ else if (exposure > sd->ctrls[EXPOSURE].min)
+ exposure--;
+ else if (gain > sd->ctrls[GAIN].min)
+ gain--;
+ else
+ break;
+ } else {
+ if (gain < sd->ctrls[GAIN].def)
+ gain++;
+ else if (exposure < exposure_knee)
+ exposure++;
+ else if (gain < gain_knee)
+ gain++;
+ else if (exposure < sd->ctrls[EXPOSURE].max)
+ exposure++;
+ else if (gain < sd->ctrls[GAIN].max)
+ gain++;
+ else
+ break;
+ }
+ }
+
+ if (gain != orig_gain) {
+ sd->ctrls[GAIN].val = gain;
+ setgain(gspca_dev);
+ retval = 1;
+ }
+ if (exposure != orig_exposure) {
+ sd->ctrls[EXPOSURE].val = exposure;
+ setexposure(gspca_dev);
+ retval = 1;
+ }
+
+ if (retval)
+ PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+ gain, exposure);
+ return retval;
+}
+
+/* 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 inline int coarse_grained_expo_autogain(
+ struct gspca_dev *gspca_dev,
+ int avg_lum,
+ int desired_avg_lum,
+ int deadzone)
+{
+ struct sd *sd = (struct sd *) gspca_dev;
+ int steps, gain, orig_gain, exposure, orig_exposure;
+ int gain_low, gain_high;
+ int retval = 0;
+
+ orig_gain = gain = sd->ctrls[GAIN].val;
+ orig_exposure = exposure = sd->ctrls[EXPOSURE].val;
+
+ gain_low = (sd->ctrls[GAIN].max - sd->ctrls[GAIN].min) / 5 * 2;
+ gain_low += sd->ctrls[GAIN].min;
+ gain_high = (sd->ctrls[GAIN].max - sd->ctrls[GAIN].min) / 5 * 4;
+ gain_high += sd->ctrls[GAIN].min;
+
+ /* 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 &&
+ exposure < sd->ctrls[EXPOSURE].max) {
+ gain = gain_high;
+ sd->exp_too_low_cnt++;
+ sd->exp_too_high_cnt = 0;
+ } else if ((gain + steps) < gain_low &&
+ exposure > sd->ctrls[EXPOSURE].min) {
+ gain = gain_low;
+ sd->exp_too_high_cnt++;
+ sd->exp_too_low_cnt = 0;
+ } else {
+ gain += steps;
+ if (gain > sd->ctrls[GAIN].max)
+ gain = sd->ctrls[GAIN].max;
+ else if (gain < sd->ctrls[GAIN].min)
+ gain = sd->ctrls[GAIN].min;
+ 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) {
+ sd->ctrls[GAIN].val = gain;
+ setgain(gspca_dev);
+ retval = 1;
+ }
+ if (exposure != orig_exposure) {
+ sd->ctrls[EXPOSURE].val = exposure;
+ setexposure(gspca_dev);
+ retval = 1;
+ }
+
+ if (retval)
+ PDEBUG(D_FRAM, "autogain: changed gain: %d, expo: %d",
+ gain, exposure);
+ return retval;
+}