avfilter: ported lenscorrection filter from frei0r

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Changelog

@@ -3,6 +3,7 @@ releases are sorted from youngest to oldest.
 
 version <next>:
 - Icecast protocol
+- ported lenscorrection filter from frei0r filter
 
 
 version 2.3:

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

doc/filters.texi

@@ -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.

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

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);

libavfilter/vf_lenscorrection.c

@@ -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,
+};