[FFmpeg-devel] [ffmpeg-devel][GSoC][PATCH 2/2] libavfilter/vf_colorconstancy.c : Adding weighted greyedge
Yatendra Singh
yatendra1999luffy at gmail.com
Thu Jul 2 02:40:55 EEST 2020
Signed-off-by: Yatendra Singh <yatendra1999luffy at gmail.com>
---
doc/filters.texi | 36 ++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_colorconstancy.c | 220 ++++++++++++++++++++++++++++++++
4 files changed, 258 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index 85a511b205..2946b5b9e6 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -20250,6 +20250,42 @@ separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave
@end example
@end itemize
+ at section weighted_greyedge
+Apply the color constancy filter which estimates illumination and updates the
+image colors accordingly.
+
+It accepts the following options:
+
+ at table @option
+ at item minknorm
+The Minkowski parameter to be used for calculating the Minkowski distance. Must
+be chosen in the range [0,20] and default value is 1. Set to 0 for getting
+max value instead of calculating Minkowski distance.
+
+ at item sigma
+The standard deviation of Gaussian blur to be applied on the scene. Must be
+chosen in the range [0,1024.0] and default value = 1. floor( @var{sigma} * break_off_sigma(3) )
+can't be equal to 0 if @var{difford} is greater than 0.
+
+ at item min_err
+The error angle between the estimated illumination and white light at which the algorithm stops even
+if it hasn't reached the required number of iterations @code{max_iters}. Must be chosen in the range
+[0.02,PI] radians with default of 0.1.
+
+ at item max_iters
+The number of iterations at which the algorithm stops even if it hasn't reached the required
+error angle between the estimated illumination and white light @code{min_err}. Must be chosen in the
+range [1,100] with a default value of 10.
+
+ at item kappa
+The power which is applied to the spectral weights to change the impact of weights on illuminant
+estimation @code{kappa}. Must be chosen in the range [1,25] with a default value of 10.
+ at end table
+
+ at example
+ffmpeg -i mondrian.tif -vf "weighted_greyedge=minknorm=0:sigma=1:max_iters=50:min_err=0.02:kappa=10" mondrian_out.tif
+ at end example
+
@section xbr
Apply the xBR high-quality magnification filter which is designed for pixel
art. It follows a set of edge-detection rules, see
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 994a4172a3..6973452f8d 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -453,6 +453,7 @@ OBJS-$(CONFIG_VSTACK_FILTER) += vf_stack.o framesync.o
OBJS-$(CONFIG_W3FDIF_FILTER) += vf_w3fdif.o
OBJS-$(CONFIG_WAVEFORM_FILTER) += vf_waveform.o
OBJS-$(CONFIG_WEAVE_FILTER) += vf_weave.o
+OBJS-$(CONFIG_WEIGHTED_GREYEDGE_FILTER) += vf_colorconstancy.o
OBJS-$(CONFIG_XBR_FILTER) += vf_xbr.o
OBJS-$(CONFIG_XFADE_FILTER) += vf_xfade.o
OBJS-$(CONFIG_XFADE_OPENCL_FILTER) += vf_xfade_opencl.o opencl.o opencl/xfade.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index f2a44b0090..ad2e07f9c5 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -432,6 +432,7 @@ extern AVFilter ff_vf_vstack;
extern AVFilter ff_vf_w3fdif;
extern AVFilter ff_vf_waveform;
extern AVFilter ff_vf_weave;
+extern AVFilter ff_vf_weighted_greyedge;
extern AVFilter ff_vf_xbr;
extern AVFilter ff_vf_xfade;
extern AVFilter ff_vf_xfade_opencl;
diff --git a/libavfilter/vf_colorconstancy.c b/libavfilter/vf_colorconstancy.c
index d974317a48..cd9d992fdd 100644
--- a/libavfilter/vf_colorconstancy.c
+++ b/libavfilter/vf_colorconstancy.c
@@ -1,5 +1,6 @@
/*
* Copyright (c) 2018 Mina Sami
+ * Copyright (c) 2020 Yatendra Singh
*
* This file is part of FFmpeg.
*
@@ -26,6 +27,14 @@
*
* @cite
* J. van de Weijer, Th. Gevers, A. Gijsenij "Edge-Based Color Constancy".
+ *
+ * @cite
+ * J. van de Weijer, Th. Gevers, and J. Geusebroek,
+ * “Edge and corner detection by photometric quasi-invariants”.
+ *
+ * @cite
+ * A. Gijsenij, Th. Gevers, J. van de Weijer,
+ * "Improving Color Constancy by Photometric Edge Weighting".
*/
#include "libavutil/imgutils.h"
@@ -40,8 +49,10 @@
#include <math.h>
#define GREY_EDGE "greyedge"
+#define WEIGHTED_GREY_EDGE "weighted_greyedge"
#define SQRT3 1.73205080757
+#define NORMAL_WHITE 1/SQRT3
#define NUM_PLANES 3
#define MAX_DIFF_ORD 2
@@ -77,12 +88,16 @@ typedef struct ColorConstancyContext {
int difford;
int minknorm; /**< @minknorm = 0 : getMax instead */
+ int kappa;
double sigma;
int nb_threads;
int planeheight[4];
int planewidth[4];
+ double min_err;
+ int max_iters;
+
int filtersize;
double *gauss[MAX_DIFF_ORD+1];
@@ -608,6 +623,170 @@ static void chromatic_adaptation(AVFilterContext *ctx, AVFrame *in, AVFrame *out
ctx->internal->execute(ctx, diagonal_transformation, &td, NULL, nb_jobs);
}
+/**
+ * Slice function for weighted grey edge algorithm that does partial summing/maximizing
+ * of gaussian derivatives and applies the pixel wise weights.
+ *
+ * @param ctx the filter context.
+ * @param arg data to be passed between threads.
+ * @param jobnr current job nubmer.
+ * @param nb_jobs total number of jobs.
+ *
+ * @return 0.
+ */
+static int filter_slice_weighted_greyedge(AVFilterContext* ctx, void *arg, int jobnr, int nb_jobs)
+{
+ ColorConstancyContext *s = ctx->priv;
+ ThreadData *td = arg;
+ AVFrame *in = td->in;
+ int minknorm = s->minknorm;
+ const uint8_t thresh = 255;
+
+ int height = s->planeheight[0];
+ int width = s->planewidth[0];
+
+ int linesize = in->linesize[0];
+ int slice_start = (height * jobnr) / nb_jobs;
+ int slice_end = (height * (jobnr+1)) / nb_jobs;
+
+ for (int h = slice_start; h < slice_end; h++) {
+ for (int w = 0; w < width; w++) {
+ double spectral_weight, spvar, norm, norm_temp;
+ double spvar_x, spvar_y;
+ spvar_x = 0;
+ spvar_y = 0;
+ norm = 0;
+ for (int plane = 0; plane < NUM_PLANES; plane++) {
+ spvar_x += td->data[INDEX_DX][plane][INDX2D(h,w,width)];
+ spvar_y += td->data[INDEX_DY][plane][INDX2D(h,w,width)];
+ norm_temp = pow(td->data[INDEX_DX][plane][INDX2D(h,w,width)], 2);
+ norm_temp += pow(td->data[INDEX_DY][plane][INDX2D(h,w,width)], 2);
+ norm += sqrt(norm_temp);
+ }
+ spvar = sqrt(pow(spvar_x * NORMAL_WHITE, 2) + pow(spvar_y * NORMAL_WHITE, 2) );
+ norm = sqrt(norm);
+ spectral_weight = pow(spvar/norm, s->kappa);
+
+ for (int plane = 0; plane < NUM_PLANES; plane++) {
+ const uint8_t *img_data = in->data[plane];
+ const double *src = td->data[INDEX_NORM][plane];
+ double *dst = td->data[INDEX_DST][plane];
+
+ if (!minknorm) {
+ spectral_weight = 1.0;
+ dst[jobnr] = FFMAX(dst[jobnr], fabs(src[INDX2D(h, w, width)]) * spectral_weight
+ * (img_data[INDX2D(h, w, linesize)] < thresh) );
+ }
+ else {
+ dst[jobnr] += (pow(fabs(src[INDX2D(h, w, width)] / 255.) * spectral_weight, minknorm)
+ * (img_data[INDX2D(h, w, linesize)] < thresh) );
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+/**
+ * Function to calculate the reproduction angular error w.r.t white light
+ *
+ * @param light the estimated illumination
+ *
+ * @return the value of the reproduction angular error
+ */
+static double get_angular_error(double *light)
+{
+ double W[NUM_PLANES];
+ double rep_err;
+ double dot;
+
+ rep_err = 0.0;
+ dot = 0.0;
+
+ for (int i = 0; i < NUM_PLANES; i++) {
+ W[i] = 1/light[i];
+ }
+ normalize_light(W);
+
+ for (int i = 0; i < NUM_PLANES; i++) {
+ W[i] *= light[i];
+ dot += W[i];
+ }
+ rep_err = acosf(dot);
+
+ return rep_err;
+}
+
+/**
+ * Main driver function for weighted grey edge algorithm.
+ *
+ * @param ctx the filter context.
+ * @param in holds the input frame.
+ * @param out holds the output frame.
+ *
+ * @return 0 in case of success, a negative value corresponding to an
+ * AVERROR code if any error has occured.
+ */
+static int filter_weighted_greyedge(AVFilterContext *ctx, AVFrame *in, AVFrame *out)
+{
+ ColorConstancyContext *s = ctx->priv;
+ ThreadData td;
+ int minknorm = s->minknorm;
+ int difford = s->difford;
+ double white[NUM_PLANES];
+ int nb_jobs = FFMIN3(s->planeheight[1], s->planewidth[1], s->nb_threads);
+ int num_iters = 0;
+ int plane, job, ret;
+ double rep_err;
+
+ td.in = in;
+ ret = setup_derivative_buffers(ctx, &td);
+ if (ret) {
+ return ret;
+ }
+
+ while (num_iters < s->max_iters ) {
+ get_derivative(ctx, &td);
+ if (difford > 0) {
+ ctx->internal->execute(ctx, slice_normalize, &td, NULL, nb_jobs);
+ }
+
+ ctx->internal->execute(ctx, filter_slice_weighted_greyedge, &td, NULL, nb_jobs);
+ if (!minknorm) {
+ for (plane = 0; plane < NUM_PLANES; plane++) {
+ white[plane] = 0; // All values are absolute
+ for (job = 0; job < nb_jobs; job++) {
+ white[plane] = FFMAX(white[plane] , td.data[INDEX_DST][plane][job]);
+ }
+ }
+ } else {
+ for (plane = 0; plane < NUM_PLANES; ++plane) {
+ white[plane] = 0;
+ for (job = 0; job < nb_jobs; job++) {
+ white[plane] += td.data[INDEX_DST][plane][job];
+ }
+ white[plane] = pow(white[plane], 1./minknorm);
+ }
+ }
+
+ for (int i = 0; i < NUM_PLANES; i++) {
+ s->white[i] = s->white[i] * white[i];
+ }
+ normalize_light(s->white);
+ chromatic_adaptation(ctx, in, out);
+
+ num_iters++;
+
+ rep_err = get_angular_error(s->white);
+ if (rep_err <= s->min_err) {
+ break;
+ }
+ }
+
+ cleanup_derivative_buffers(&td, difford + 1, NUM_PLANES);
+ return 0;
+}
+
static int query_formats(AVFilterContext *ctx)
{
static const enum AVPixelFormat pix_fmts[] = {
@@ -629,6 +808,8 @@ static int config_props(AVFilterLink *inlink)
double sigma = s->sigma;
int ret;
+ s->difford = 1;
+
if (!floor(break_off_sigma * sigma + 0.5) && s->difford) {
av_log(ctx, AV_LOG_ERROR, "floor(%f * sigma) must be > 0 when difford > 0.\n", break_off_sigma);
return AVERROR(EINVAL);
@@ -680,6 +861,18 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
}
chromatic_adaptation(ctx, in, out);
}
+ else if (!strcmp(ctx->filter->name, WEIGHTED_GREY_EDGE)) {
+ ColorConstancyContext *s = ctx->priv;
+ for (int i = 0; i < NUM_PLANES; i++) {
+ s->white[i] = NORMAL_WHITE;
+ }
+ chromatic_adaptation(ctx, in, out);
+ ret = filter_weighted_greyedge(ctx, in, out);
+ if (ret) {
+ av_frame_free(&in);
+ return ret;
+ }
+ }
if (!direct)
av_frame_free(&in);
@@ -740,3 +933,30 @@ AVFilter ff_vf_greyedge = {
};
#endif /* CONFIG_GREY_EDGE_FILTER */
+
+#if CONFIG_WEIGHTED_GREYEDGE_FILTER
+
+static const AVOption weighted_greyedge_options[] = {
+ { "minknorm", "set Minkowski norm", OFFSET(minknorm), AV_OPT_TYPE_INT, {.i64=1}, 0, 20, FLAGS },
+ { "sigma", "set sigma", OFFSET(sigma), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0.0, 1024.0, FLAGS },
+ { "min_err", "set minimum angular error", OFFSET(min_err), AV_OPT_TYPE_DOUBLE, {.dbl=0.1}, 0.02, M_PI, FLAGS },
+ { "max_iters", "set the maximum iterations", OFFSET(max_iters), AV_OPT_TYPE_INT, {.i64=10}, 1, 100, FLAGS },
+ { "kappa", "set the kappa for weights", OFFSET(kappa), AV_OPT_TYPE_INT, {.i64=10}, 1, 100, FLAGS },
+ { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(weighted_greyedge);
+
+AVFilter ff_vf_weighted_greyedge = {
+ .name = WEIGHTED_GREY_EDGE,
+ .description = NULL_IF_CONFIG_SMALL("Estimate scene illumination by grey edge assumption."),
+ .priv_size = sizeof(ColorConstancyContext),
+ .priv_class = &weighted_greyedge_class,
+ .query_formats = query_formats,
+ .uninit = uninit,
+ .inputs = colorconstancy_inputs,
+ .outputs = colorconstancy_outputs,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
+};
+
+#endif /* CONFIG_WEIGHTED_GREY_EDGE_FILTER */
--
2.20.1
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