diff options
Diffstat (limited to 'v4l2-apps/libv4l/libv4lconvert/processing/autogain.c')
| -rw-r--r-- | v4l2-apps/libv4l/libv4lconvert/processing/autogain.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/v4l2-apps/libv4l/libv4lconvert/processing/autogain.c b/v4l2-apps/libv4l/libv4lconvert/processing/autogain.c new file mode 100644 index 000000000..ed4b8224f --- /dev/null +++ b/v4l2-apps/libv4l/libv4lconvert/processing/autogain.c @@ -0,0 +1,140 @@ +/* +# (C) 2008-2009 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 Lesser General Public License as published by +# the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser 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 +*/ + +#include <errno.h> +#include <string.h> +#include <stdio.h> +#include <stdlib.h> +#include <syscall.h> +#include <unistd.h> + +#include "libv4lprocessing.h" +#include "libv4lprocessing-priv.h" +#include "../libv4lconvert-priv.h" /* for PIX_FMT defines */ + +static int autogain_active(struct v4lprocessing_data *data) { + return v4lcontrol_get_ctrl(data->control, V4LCONTROL_AUTOGAIN); +} + +/* auto gain and exposure algorithm based on the knee algorithm described here: + http://ytse.tricolour.net/docs/LowLightOptimization.html */ +static int autogain_calculate_lookup_tables( + struct v4lprocessing_data *data, + unsigned char *buf, const struct v4l2_format *fmt) +{ + int x, y, target, steps, avg_lum = 0; + int gain, exposure, orig_gain, orig_exposure; + struct v4l2_control ctrl; + struct v4l2_queryctrl gainctrl, expoctrl; + const int deadzone = 8; + + ctrl.id = V4L2_CID_EXPOSURE; + expoctrl.id = V4L2_CID_EXPOSURE; + if (syscall(SYS_ioctl, data->fd, VIDIOC_QUERYCTRL, &expoctrl) || + syscall(SYS_ioctl, data->fd, VIDIOC_G_CTRL, &ctrl)) + return 0; + exposure = orig_exposure = ctrl.value; + + ctrl.id = V4L2_CID_GAIN; + gainctrl.id = V4L2_CID_GAIN; + if (syscall(SYS_ioctl, data->fd, VIDIOC_QUERYCTRL, &gainctrl) || + syscall(SYS_ioctl, data->fd, VIDIOC_G_CTRL, &ctrl)) + return 0; + gain = orig_gain = ctrl.value; + + switch (fmt->fmt.pix.pixelformat) { + case V4L2_PIX_FMT_SGBRG8: + case V4L2_PIX_FMT_SGRBG8: + case V4L2_PIX_FMT_SBGGR8: + case V4L2_PIX_FMT_SRGGB8: + buf += fmt->fmt.pix.height * fmt->fmt.pix.bytesperline / 4 + + fmt->fmt.pix.width / 4; + + for (y = 0; y < fmt->fmt.pix.height / 2; y++) { + for (x = 0; x < fmt->fmt.pix.width / 2; x++) { + avg_lum += *buf++; + } + buf += fmt->fmt.pix.bytesperline - fmt->fmt.pix.width / 2; + } + avg_lum /= fmt->fmt.pix.height * fmt->fmt.pix.width / 4; + break; + + case V4L2_PIX_FMT_RGB24: + case V4L2_PIX_FMT_BGR24: + buf += fmt->fmt.pix.height * fmt->fmt.pix.bytesperline / 4 + + fmt->fmt.pix.width * 3 / 4; + + for (y = 0; y < fmt->fmt.pix.height / 2; y++) { + for (x = 0; x < fmt->fmt.pix.width / 2; x++) { + avg_lum += *buf++; + avg_lum += *buf++; + avg_lum += *buf++; + } + buf += fmt->fmt.pix.bytesperline - fmt->fmt.pix.width * 3 / 2; + } + avg_lum /= fmt->fmt.pix.height * fmt->fmt.pix.width * 3 / 4; + break; + } + + /* If we are off a multiple of deadzone, do multiple steps to reach the + desired lumination fast (with the risc of a slight overshoot) */ + target = v4lcontrol_get_ctrl(data->control, V4LCONTROL_AUTOGAIN_TARGET); + steps = abs(target - avg_lum) / deadzone; + + for (x = 0; x < steps; x++) { + if (avg_lum > target) { + if (exposure > expoctrl.default_value) + exposure--; + else if (gain > gainctrl.default_value) + gain--; + else if (exposure > expoctrl.minimum) + exposure--; + else if (gain > gainctrl.minimum) + gain--; + else + break; + } else { + if (gain < gainctrl.default_value) + gain++; + else if (exposure < expoctrl.default_value) + exposure++; + else if (gain < gainctrl.maximum) + gain++; + else if (exposure < expoctrl.maximum) + exposure++; + else + break; + } + } + + if (gain != orig_gain) { + ctrl.id = V4L2_CID_GAIN; + ctrl.value = gain; + syscall(SYS_ioctl, data->fd, VIDIOC_S_CTRL, &ctrl); + } + if (exposure != orig_exposure) { + ctrl.id = V4L2_CID_EXPOSURE; + ctrl.value = exposure; + syscall(SYS_ioctl, data->fd, VIDIOC_S_CTRL, &ctrl); + } + + return 0; +} + +struct v4lprocessing_filter autogain_filter = { + autogain_active, autogain_calculate_lookup_tables }; |