[FFmpeg-devel] rectification filter
Michael Niedermayer
michaelni at gmx.at
Fri Aug 8 12:10:19 CEST 2014
On Thu, Aug 07, 2014 at 12:15:17AM +0200, Daniel Oberhoff wrote:
>
> Am 06.08.2014 um 12:12 schrieb Clément Bœsch <u at pkh.me>:
>
> > On Sun, Aug 03, 2014 at 06:43:18PM +0200, Daniel Oberhoff wrote:
> > [...]
> >>>> +static av_cold int init(AVFilterContext *ctx)
> >>>> +{
> >>>> + return 0;
> >>>> +}
> >>>>
> >>>
> >>> please remove this one, there is no point in having code that does nothing.
> >>>
> >>>> +
> >>>> +static av_cold void uninit(AVFilterContext *ctx)
> >>>> +{
> >>>> +}
> >>>> +
> >>>>
> >>>
> >>> ditto
> >>>
> >>
> >> Done thanks!
> >>
> >
> > Did you forget to attach the latest version of the patch or I missed it
> > somewhere in the thread?
>
> Sorry, think that day I wanted to add something else before resubmit, and then lost the time.
>
> Here also with changes suggested by timothy. Note that the parametrization is now traditional
> (i.e. k1 and k2 are zero-based, as for example in the opencv documentation about calibration).
>
> From b798b95eb2f9ec4043b2407970d351cc31dd9e6a Mon Sep 17 00:00:00 2001
> From: Daniel Oberhoff <daniel at danieloberhoff.de>
> Date: Mon, 28 Jul 2014 23:58:12 +0200
> Subject: [PATCH] avfilter: ported lenscorrection filter from frei0r
>
> ---
> Changelog | 2 +-
> MAINTAINERS | 1 +
> doc/filters.texi | 46 +++++++
> libavfilter/Makefile | 1 +
> libavfilter/allfilters.c | 1 +
> libavfilter/version.h | 4 +-
> libavfilter/vf_lenscorrection.c | 199 +++++++++++++++++++++++++++
> tests/fate/filter-video.mak | 3 +
> tests/ref/fate/filter-pixfmts-lenscorrection | 8 ++
> 9 files changed, 262 insertions(+), 3 deletions(-)
> create mode 100644 libavfilter/vf_lenscorrection.c
> create mode 100644 tests/ref/fate/filter-pixfmts-lenscorrection
>
This is missing a "Signed-off-by" from you
> diff --git a/Changelog b/Changelog
> index 25dd210..79393ce 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -3,7 +3,7 @@ releases are sorted from youngest to oldest.
>
> version <next>:
> - Icecast protocol
> -
> +- ported lenscorrection filter from frei0r filter
>
> version 2.3:
> - AC3 fixed-point decoding
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c383d3f..6948e22 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -354,6 +354,7 @@ Filters:
> vf_histogram.c Paul B Mahol
> vf_hqx.c Clément Bœsch
> vf_il.c Paul B Mahol
> + vf_lenscorrection.c Daniel Oberhoff
> vf_mergeplanes.c Paul B Mahol
> vf_psnr.c Paul B Mahol
> vf_scale.c Michael Niedermayer
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 86feebc..c4888d3 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -5532,6 +5532,51 @@ kerndeint=map=1
> @end example
> @end itemize
>
> + at section lenscorrection
> +
> +Correct radial lens distortion
> +
> +This filter can be used to correct for radial distortion as can result from the use
> +of wide angle lenses, and thereby re-rectify the image. To find the right parameters
> +one can use tools available for example as part of opencv or simply trial-and-error.
> +To use opencv use the calibration sample (under samples/cpp) from the opencv sources
> +and extract the k1 and k2 coefficients from the resulting matrix.
> +
> +Note that effectively the same filter is available in the open-source tools Krita and
> +Digikam from the KDE project.
> +
> +In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors,
> +this filter corrects the distortion of the image, whereas @ref{vignette} corrects the
> +brightness distribution, so you may want to use both filters together in certain
> +cases, though you will have to take care of ordering, i.e. whether vignetting should
> +be applied before or after lens correction.
> +
> + at subsection Options
> +
> +The filter accepts the following options:
> +
> + at table @option
> + at item cx
> +Relative x-coordinate of the focal point of the image, and thereby the center of the
> +distrortion. This value has a range [0,1] and is expressed as fractions of the image
> +width.
> + at item cy
> +Relative y-coordinate of the focal point of the image, and thereby the center of the
> +distrortion. This value has a range [0,1] and is expressed as fractions of the image
> +height.
> + at item k1
> +Coefficient of the quadratic correction term. 0.5 means no correction.
> + at item k2
> +Coefficient of the double quadratic correction term. 0.5 means no correction.
> + at end table
> +
> +The formula that generates the correction is:
> +
> + at var{r_src} = @var{r_tgt} * (1 + @var{k1} * (@var{r_tgt} / @var{r_0})^2 + @var{k2} * (@var{r_tgt} / @var{r_0})^4)
> +
> +where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the
> +distances from the focal point in the source and target images, respectively.
> +
> @anchor{lut3d}
> @section lut3d
>
> @@ -8744,6 +8789,7 @@ For example, to vertically flip a video with @command{ffmpeg}:
> ffmpeg -i in.avi -vf "vflip" out.avi
> @end example
>
> + at anchor{vignette}
> @section vignette
>
> Make or reverse a natural vignetting effect.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 0f54381..e9c8456 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -138,6 +138,7 @@ OBJS-$(CONFIG_IL_FILTER) += vf_il.o
> OBJS-$(CONFIG_INTERLACE_FILTER) += vf_interlace.o
> OBJS-$(CONFIG_INTERLEAVE_FILTER) += f_interleave.o
> OBJS-$(CONFIG_KERNDEINT_FILTER) += vf_kerndeint.o
> +OBJS-$(CONFIG_LENSCORRECTION_FILTER) += vf_lenscorrection.o
> OBJS-$(CONFIG_LUT3D_FILTER) += vf_lut3d.o
> OBJS-$(CONFIG_LUT_FILTER) += vf_lut.o
> OBJS-$(CONFIG_LUTRGB_FILTER) += vf_lut.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 1877557..b1d6ff5 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -156,6 +156,7 @@ void avfilter_register_all(void)
> REGISTER_FILTER(INTERLACE, interlace, vf);
> REGISTER_FILTER(INTERLEAVE, interleave, vf);
> REGISTER_FILTER(KERNDEINT, kerndeint, vf);
> + REGISTER_FILTER(LENSCORRECTION, lenscorrection, vf);
> REGISTER_FILTER(LUT3D, lut3d, vf);
> REGISTER_FILTER(LUT, lut, vf);
> REGISTER_FILTER(LUTRGB, lutrgb, vf);
> diff --git a/libavfilter/version.h b/libavfilter/version.h
> index 1a43dc5..47bac78 100644
> --- a/libavfilter/version.h
> +++ b/libavfilter/version.h
> @@ -30,8 +30,8 @@
> #include "libavutil/version.h"
>
> #define LIBAVFILTER_VERSION_MAJOR 4
> -#define LIBAVFILTER_VERSION_MINOR 11
> -#define LIBAVFILTER_VERSION_MICRO 102
> +#define LIBAVFILTER_VERSION_MINOR 12
> +#define LIBAVFILTER_VERSION_MICRO 100
>
> #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
> LIBAVFILTER_VERSION_MINOR, \
> diff --git a/libavfilter/vf_lenscorrection.c b/libavfilter/vf_lenscorrection.c
> new file mode 100644
> index 0000000..c2346db
> --- /dev/null
> +++ b/libavfilter/vf_lenscorrection.c
> @@ -0,0 +1,199 @@
> +/*
> + * Copyright (C) 2007 Richard Spindler (author of frei0r plugin from which this was derived)
> + * Copyright (C) 2014 Daniel Oberhoff
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg 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.
> + *
> + * FFmpeg 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 FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * Lenscorrection filter, algorithm from the frei0r plugin with the same name
> +*/
> +#include <stdlib.h>
> +#include <math.h>
> +
> +#include "libavutil/opt.h"
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/pixdesc.h"
> +
> +#include "avfilter.h"
> +#include "internal.h"
> +#include "video.h"
> +
> +typedef struct LenscorrectionCtx {
> + const AVClass *av_class;
> + unsigned int width;
> + unsigned int height;
> + int hsub, vsub;
> + int nb_planes;
> + double cx, cy, k1, k2;
> +} LenscorrectionCtx;
> +
> +#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
> +static const AVOption lenscorrection_options[] = {
> + { "cx", "set relative center x", offsetof(LenscorrectionCtx, cx), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 1, .flags=FLAGS },
> + { "cy", "set relative center y", offsetof(LenscorrectionCtx, cy), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 1, .flags=FLAGS },
> + { "k1", "set quadratic distortion factor", offsetof(LenscorrectionCtx, k1), AV_OPT_TYPE_DOUBLE, {.dbl=0.0}, -1, 1, .flags=FLAGS },
> + { "k2", "set double quadratic distortion factor", offsetof(LenscorrectionCtx, k2), AV_OPT_TYPE_DOUBLE, {.dbl=0.0}, -1, 1, .flags=FLAGS },
> + { NULL }
> +};
> +
> +AVFILTER_DEFINE_CLASS(lenscorrection);
> +
> +typedef struct ThreadData {
> + AVFrame *in, *out;
> + float w, h;
> + int plane;
> + float xcenter, ycenter;
> + float k1, k2;
> +} ThreadData;
> +
> +static int filter_slice(AVFilterContext *ctx, void *arg, int job, int nb_jobs)
> +{
> + ThreadData *td = (ThreadData*)arg;
> + AVFrame *in = td->in;
> + AVFrame *out = td->out;
> +
> + const float w = td->w, h = td->h;
> + const float xcenter = td->xcenter;
> + const float ycenter = td->ycenter;
> + const float r2inv = 4.0 / (w * w + h * h);
> + const float k1 = td->k1;
> + const float k2 = td->k2;
> + const int start = (h * job ) / nb_jobs;
> + const int end = (h * (job+1)) / nb_jobs;
> + const int plane = td->plane;
> + const int inlinesize = in->linesize[plane];
> + const int outlinesize = out->linesize[plane];
> + const uint8_t *indata = in->data[plane];
> + uint8_t *outrow = out->data[plane] + start * outlinesize;
> + int i;
> + for (i = start; i < end; i++, outrow += outlinesize) {
> + const float off_y = i - ycenter;
> + const float off_y2 = off_y * off_y;
> + uint8_t *out = outrow;
> + int j;
> + for (j = 0; j < w; j++) {
> + const float off_x = j - xcenter;
> + const float r2 = (off_x * off_x + off_y2) * r2inv;
> + const float radius_mult = 1.0f + r2 * k1 + r2 * r2 * k2;
> + const int x = xcenter + radius_mult * off_x + 0.5f;
> + const int y = ycenter + radius_mult * off_y + 0.5f;
> + const char isvalid = x > 0 && x < w - 1 && y > 0 && y < h - 1;
> + *out++ = isvalid ? indata[y * inlinesize + x] : 0;
IMHO "nearest neighbour" resampling isnt a reasonable choice, if
thats the only choice the user has.
also md5 based regression tests and extensive use of floats are
unlikely to work together, different architectures/platforms or even
compiler versions might give you different results
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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