@@ -3,6 +3,7 @@ releases are sorted from youngest to oldest.

 version <next>:

 - Icecast protocol

+- ported lenscorrection filter from frei0r filter

 version 2.3:

@@ -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

@@ -5546,6 +5546,51 @@ kerndeint=map=1

 @end example

 @end itemize

+@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.

+

+@subsection Options

+

+The filter accepts the following options:

+

+@table @option

+@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.

+@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.

+@item k1

+Coefficient of the quadratic correction term. 0.5 means no correction.

+@item k2

+Coefficient of the double quadratic correction term. 0.5 means no correction.

+@end table

+

+The formula that generates the correction is:

+

+@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

@@ -8758,6 +8803,7 @@ For example, to vertically flip a video with @command{ffmpeg}:

 ffmpeg -i in.avi -vf "vflip" out.avi

 @end example

+@anchor{vignette}

 @section vignette

 Make or reverse a natural vignetting effect.

@@ -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

@@ -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);

new file mode 100644

@@ -0,0 +1,198 @@

+/*

+ * 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;

+        }

+    }

+    return 0;

+}

+

+static int query_formats(AVFilterContext *ctx)

+{

+    static enum AVPixelFormat pix_fmts[] = {

+        AV_PIX_FMT_YUV410P,

+        AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUVJ444P,

+        AV_PIX_FMT_YUV420P,  AV_PIX_FMT_YUVJ420P,

+        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA420P,

+        AV_PIX_FMT_YUV422P,

+        AV_PIX_FMT_NONE

+    };

+

+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

+    return 0;

+}

+

+static int config_props(AVFilterLink *outlink)

+{

+    AVFilterContext *ctx = outlink->src;

+    LenscorrectionCtx *rect = ctx->priv;

+    AVFilterLink *inlink = ctx->inputs[0];

+    const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(inlink->format);

+    rect->hsub = pixdesc->log2_chroma_w;

+    rect->vsub = pixdesc->log2_chroma_h;

+    outlink->w = rect->width = inlink->w;

+    outlink->h = rect->height = inlink->h;

+    rect->nb_planes = av_pix_fmt_count_planes(inlink->format);

+    return 0;

+}

+

+static int filter_frame(AVFilterLink *inlink, AVFrame *in)

+{

+    AVFilterContext *ctx = inlink->dst;

+    AVFilterLink *outlink = ctx->outputs[0];

+    LenscorrectionCtx *rect = (LenscorrectionCtx*)ctx->priv;

+    AVFrame *out = ff_get_video_buffer(outlink, outlink->w, outlink->h);

+    int plane;

+

+    if (!out) {

+        av_frame_free(&in);

+        return AVERROR(ENOMEM);

+    }

+

+    av_frame_copy_props(out, in);

+

+    for (plane = 0; plane < rect->nb_planes; ++plane) {

+        int hsub = plane == 1 || plane == 2 ? rect->hsub : 0;

+        int vsub = plane == 1 || plane == 2 ? rect->vsub : 0;

+        float hdiv = 1 << hsub;

+        float vdiv = 1 << vsub;

+        float w = rect->width / hdiv;

+        float h = rect->height / vdiv;

+        ThreadData td = {

+            .in = in,

+            .out  = out,

+            .w  = w,

+            .h  = h,

+            .xcenter = rect->cx * w,

+            .ycenter = rect->cy * h,

+            .k1 = rect->k1,

+            .k2 = rect->k2,

+            .plane = plane};

+        ctx->internal->execute(ctx, filter_slice, &td, NULL, FFMIN(h, ctx->graph->nb_threads));

+    }

+

+    av_frame_free(&in);

+    return ff_filter_frame(outlink, out);

+}

+

+static const AVFilterPad lenscorrection_inputs[] = {

+    {

+        .name         = "default",

+        .type         = AVMEDIA_TYPE_VIDEO,

+        .filter_frame = filter_frame,

+    },

+    { NULL }

+};

+

+static const AVFilterPad lenscorrection_outputs[] = {

+    {

+        .name         = "default",

+        .type         = AVMEDIA_TYPE_VIDEO,

+        .config_props = config_props,

+    },

+    { NULL }

+};

+

+AVFilter ff_vf_lenscorrection = {

+    .name          = "lenscorrection",

+    .description   = NULL_IF_CONFIG_SMALL("Rectify the image by correcting for lens distortion."),

+    .priv_size     = sizeof(LenscorrectionCtx),

+    .query_formats = query_formats,

+    .inputs        = lenscorrection_inputs,

+    .outputs       = lenscorrection_outputs,

+    .priv_class    = &lenscorrection_class,

+    .flags         = AVFILTER_FLAG_SLICE_THREADS,

+};