[FFmpeg-devel] [PATCH 1/1] Add grayworld color correction filer
Paul Buxton
paulbuxton.mail at googlemail.com
Sun Aug 22 16:53:34 EEST 2021
Signed-off-by: Paul Buxton <paulbuxton.mail at googlemail.com>
---
MAINTAINERS | 1 +
doc/filters.texi | 14 ++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/version.h | 2 +-
libavfilter/vf_grayworld.c | 401 +++++++++++++++++++++++++++++++++++++
6 files changed, 419 insertions(+), 1 deletion(-)
create mode 100644 libavfilter/vf_grayworld.c
diff --git a/MAINTAINERS b/MAINTAINERS
index dcac46003e..207a53871b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -369,6 +369,7 @@ Filters:
vf_tonemap_opencl.c Ruiling Song
vf_yadif.c Michael Niedermayer
vf_zoompan.c Paul B Mahol
+ vf_grayworld.c Paul Buxton (CC paulbuxton.mail at googlemail.com)
Sources:
vsrc_mandelbrot.c Michael Niedermayer
diff --git a/doc/filters.texi b/doc/filters.texi
index b902aca12d..06d2eb3a5a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -13087,6 +13087,20 @@ greyedge=difford=1:minknorm=0:sigma=2
@end itemize
+
+ at section greyworld
+A color constancy filter that applies color correction based on the grayworld assumption
+
+See: @url{https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging}
+
+The algorithm linear light, so input
+data should be linearized beforehand (and possibly correctly tagged).
+
+ at example
+ffmpeg -i INPUT -vf zscale=transfer=linear,grayworld,zscale=transfer=bt709,format=yuv420p OUTPUT
+ at end example
+
+
@section guided
Apply guided filter for edge-preserving smoothing, dehazing and so on.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 102ce7beff..84ba69bba7 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -464,6 +464,7 @@ OBJS-$(CONFIG_TRANSPOSE_NPP_FILTER) += vf_transpose_npp.o
OBJS-$(CONFIG_TRANSPOSE_OPENCL_FILTER) += vf_transpose_opencl.o opencl.o opencl/transpose.o
OBJS-$(CONFIG_TRANSPOSE_VAAPI_FILTER) += vf_transpose_vaapi.o vaapi_vpp.o
OBJS-$(CONFIG_TRIM_FILTER) += trim.o
+OBJS-$(CONFIG_GRAYWORLD_FILTER) += vf_grayworld.o
OBJS-$(CONFIG_UNPREMULTIPLY_FILTER) += vf_premultiply.o framesync.o
OBJS-$(CONFIG_UNSHARP_FILTER) += vf_unsharp.o
OBJS-$(CONFIG_UNSHARP_OPENCL_FILTER) += vf_unsharp_opencl.o opencl.o \
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 73040d2824..bf9356cee5 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -442,6 +442,7 @@ extern const AVFilter ff_vf_transpose_npp;
extern const AVFilter ff_vf_transpose_opencl;
extern const AVFilter ff_vf_transpose_vaapi;
extern const AVFilter ff_vf_trim;
+extern const AVFilter ff_vf_grayworld;
extern const AVFilter ff_vf_unpremultiply;
extern const AVFilter ff_vf_unsharp;
extern const AVFilter ff_vf_unsharp_opencl;
diff --git a/libavfilter/version.h b/libavfilter/version.h
index bcd27aa6e8..e9a76c5ac3 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -30,7 +30,7 @@
#include "libavutil/version.h"
#define LIBAVFILTER_VERSION_MAJOR 8
-#define LIBAVFILTER_VERSION_MINOR 3
+#define LIBAVFILTER_VERSION_MINOR 4
#define LIBAVFILTER_VERSION_MICRO 100
diff --git a/libavfilter/vf_grayworld.c b/libavfilter/vf_grayworld.c
new file mode 100644
index 0000000000..d41b116576
--- /dev/null
+++ b/libavfilter/vf_grayworld.c
@@ -0,0 +1,401 @@
+/*
+ * Copyright (c) 2021 Paul Buxton
+ *
+ * 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
+ * Color correction filter based on
+ * https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging
+ *
+ */
+
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/intreadwrite.h"
+
+#include "avfilter.h"
+#include "drawutils.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct ThreadData {
+ AVFrame* in, * out;
+ float l_avg;
+ float a_avg;
+ float b_avg;
+ const AVPixFmtDescriptor* desc;
+ const AVPixFmtDescriptor* odesc;
+} ThreadData;
+
+typedef struct GrayWorldContext {
+ const AVClass* class;
+ int64_t stretch_histogram;
+ int64_t smoothing_frames;
+ int64_t correction_type;
+
+ float* tmppl;
+ float* tmppa;
+ float* tmppb;
+
+ float* line_suml;
+ float* line_suma;
+ float* line_sumb;
+
+ int* line_count_pels;
+} GrayWorldContext;
+
+#define OFFSET(x) offsetof(GrayWorldContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_RUNTIME_PARAM
+static const AVOption grayworld_options[] = {
+ {NULL} };
+
+AVFILTER_DEFINE_CLASS(grayworld);
+
+void compute_correction(GrayWorldContext* s, ThreadData* td);
+void apply_matrix(float matrix[3][3], float input[3], float output[3]);
+void rgb2lab(float rgb[3], float lab[3]);
+void lab2rgb(float lab[3], float rgb[3]);
+
+
+
+static int query_formats(AVFilterContext* ctx)
+{
+ static const enum AVPixelFormat pix_fmts[] = {
+ AV_PIX_FMT_GBRPF32,
+ AV_PIX_FMT_GBRAPF32,
+ AV_PIX_FMT_NONE,
+ };
+
+ AVFilterFormats* fmts_list = ff_make_format_list(pix_fmts);
+ if (!fmts_list)
+ return AVERROR(ENOMEM);
+ return ff_set_common_formats(ctx, fmts_list);
+}
+
+void apply_matrix(float matrix[3][3], float input[3], float output[3])
+{
+ for (int row = 0; row < 3; ++row) {
+ output[row] = matrix[row][0] * input[0] + matrix[row][1] * input[1] + matrix[row][2] * input[2];
+ }
+}
+
+
+float lms2lab[3][3] = {
+ {0.5774, 0.5774, 0.5774},
+ {0.40825, 0.40825, -0.816458},
+ {0.707, -0.707, 0}
+};
+
+float lab2lms[3][3] = {
+ {0.57735, 0.40825, 0.707},
+ {0.57735, 0.40825, -0.707},
+ {0.57735, -0.8165, 0}
+};
+
+float rgb2lms[3][3] = {
+ {0.3811, 0.5783, 0.0402},
+ {0.1967, 0.7244, 0.0782},
+ {0.0241, 0.1288, 0.8444}
+};
+
+float lms2rgb[3][3] = {
+ {4.4679, -3.5873, 0.1193},
+ {-1.2186, 2.3809, -0.1624},
+ {0.0497, -0.2439, 1.2045}
+};
+
+/**
+ * Convert from Linear RGB to logspace LAB
+ *
+ * @param rgb Input array of rgb components
+ * @param lab output array of lab components
+ */
+void rgb2lab(float rgb[3], float lab[3])
+{
+ float lms[3];
+ apply_matrix(rgb2lms, rgb, lms);
+ lms[0] = log(lms[0]);
+ lms[1] = log(lms[1]);
+ lms[2] = log(lms[2]);
+ apply_matrix(lms2lab, lms, lab);
+}
+
+
+/**
+ * Convert from Logspace LAB to Linear RGB
+ *
+ * @param lab input array of lab components
+ * @param rgb output array of rgb components
+ */
+void lab2rgb(float lab[3], float rgb[3])
+{
+ float lms[3];
+ apply_matrix(lab2lms, lab, lms);
+ lms[0] = exp(lms[0]);
+ lms[1] = exp(lms[1]);
+ lms[2] = exp(lms[2]);
+ apply_matrix(lms2rgb, lms, rgb);
+}
+
+/**
+ *
+ * Convert a frame from linear RGB to logspace LAB, and accumulate channel totals for each row
+ * Convert from RGB -> lms using equation 4 in color transfer paper.
+ *
+ * @param ctx Filter context
+ * @param arg Thread data pointer
+ * @param jobnr job number
+ * @param nb_jobs number of jobs
+ */
+static int convert_frame(AVFilterContext* ctx, void* arg, int jobnr, int nb_jobs)
+{
+ GrayWorldContext* s = ctx->priv;
+ ThreadData* td = arg;
+ AVFrame* in = td->in;
+ AVFrame* out = td->out;
+ AVFilterLink* outlink = ctx->outputs[0];
+ const int slice_start = (out->height * jobnr) / nb_jobs;
+ const int slice_end = (out->height * (jobnr + 1)) / nb_jobs;
+ float rgb[3];
+ float lab[3];
+
+
+
+ for (unsigned int i = slice_start; i < slice_end; i++) {
+ float* g_in_row = (float*)(in->data[0] + i * in->linesize[0]);
+ float* b_in_row = (float*)(in->data[1] + i * in->linesize[1]);
+ float* r_in_row = (float*)(in->data[2] + i * in->linesize[2]);
+ float* lcur = s->tmppl + (i * outlink->w);
+ float* acur = s->tmppa + (i * outlink->w);
+ float* bcur = s->tmppb + (i * outlink->w);
+
+ s->line_suml[i] = 0.0;
+ s->line_suma[i] = 0.0;
+ s->line_sumb[i] = 0.0;
+ s->line_count_pels[i] = 0;
+
+ for (unsigned int j = 0; j < outlink->w; j++) {
+ rgb[0] = r_in_row[j * td->desc->comp[0].step / sizeof(float)];
+ rgb[1] = g_in_row[j * td->desc->comp[0].step / sizeof(float)];
+ rgb[2] = b_in_row[j * td->desc->comp[0].step / sizeof(float)];
+ rgb2lab(rgb, lab);
+ *(lcur++) = lab[0];
+ *(acur++) = lab[1];
+ *(bcur++) = lab[2];
+ s->line_suml[i] += lab[0];
+ s->line_suma[i] += lab[1];
+ s->line_sumb[i] += lab[2];
+ s->line_count_pels[i]++;
+ }
+ }
+ return 0;
+}
+
+/**
+ *
+ * Sum the channel totals and compute the median for each channel
+ *
+ * @param s Frame context
+ * @param td thread data
+ */
+void compute_correction(GrayWorldContext* s, ThreadData* td)
+{
+ float lsum = 0.0;
+ float asum = 0.0;
+ float bsum = 0.0;
+ float pixels = 0;
+ for (int y = 0; y < td->out->height; ++y) {
+ lsum += s->line_suml[y];
+ asum += s->line_suma[y];
+ bsum += s->line_sumb[y];
+ pixels += s->line_count_pels[y];
+ }
+ td->l_avg = lsum / pixels;
+ td->a_avg = asum / pixels;
+ td->b_avg = bsum / pixels;
+}
+
+
+/**
+ *
+ * Subtract the median logspace AB values from each pixel.
+ *
+ * @param ctx Filter context
+ * @param arg Thread data pointer
+ * @param jobnr job number
+ * @param nb_jobs number of jobs
+ */
+static int correct_frame(AVFilterContext* ctx, void* arg, int jobnr, int nb_jobs)
+{
+ GrayWorldContext* s = ctx->priv;
+ ThreadData* td = arg;
+ AVFrame* out = td->out;
+ AVFilterLink* outlink = ctx->outputs[0];
+ const int slice_start = (out->height * jobnr) / nb_jobs;
+ const int slice_end = (out->height * (jobnr + 1)) / nb_jobs;
+
+ float rgb[3];
+ float lab[3];
+
+ for (int i = slice_start; i < slice_end; i++) {
+ float* g_out_row = (float*)(out->data[0] + i * out->linesize[0]);
+ float* b_out_row = (float*)(out->data[1] + i * out->linesize[1]);
+ float* r_out_row = (float*)(out->data[2] + i * out->linesize[2]);
+ float* lcur = s->tmppl + (i * outlink->w);
+ float* acur = s->tmppa + (i * outlink->w);
+ float* bcur = s->tmppb + (i * outlink->w);
+
+ for (int j = 0; j < outlink->w; j++) {
+ lab[0] = *lcur++;
+ lab[1] = *acur++;
+ lab[2] = *bcur++;
+
+ // subtract the average for the color channels
+ lab[1] -= td->a_avg;
+ lab[2] -= td->b_avg;
+
+ //convert back to linear rgb
+ lab2rgb(lab, rgb);
+ r_out_row[j * td->odesc->comp[0].step / sizeof(float)] = rgb[0];
+ g_out_row[j * td->odesc->comp[1].step / sizeof(float)] = rgb[1];
+ b_out_row[j * td->odesc->comp[2].step / sizeof(float)] = rgb[2];
+ }
+ }
+ return 0;
+}
+
+
+static int config_input(AVFilterLink* inlink)
+{
+ GrayWorldContext* s = inlink->dst->priv;
+
+ s->tmppl = av_malloc(inlink->h * inlink->w * sizeof(float));
+ s->tmppa = av_malloc(inlink->h * inlink->w * sizeof(float));
+ s->tmppb = av_malloc(inlink->h * inlink->w * sizeof(float));
+
+ s->line_count_pels = av_malloc(inlink->h * sizeof(int));
+
+ s->line_suml = av_malloc(inlink->h * sizeof(float));
+ s->line_suma = av_malloc(inlink->h * sizeof(float));
+ s->line_sumb = av_malloc(inlink->h * sizeof(float));
+
+ return 0;
+}
+
+static av_cold void uninit(AVFilterContext* ctx)
+{
+ GrayWorldContext* s = ctx->priv;
+
+ av_freep(&s->tmppl);
+ av_freep(&s->tmppa);
+ av_freep(&s->tmppb);
+
+ av_freep(&s->line_count_pels);
+
+ av_freep(&s->line_suml);
+ av_freep(&s->line_suma);
+ av_freep(&s->line_sumb);
+}
+
+static int filter_frame(AVFilterLink* inlink, AVFrame* in)
+{
+ AVFilterContext* ctx = inlink->dst;
+ GrayWorldContext* s = ctx->priv;
+ AVFilterLink* outlink = ctx->outputs[0];
+ ThreadData td;
+ AVFrame* out;
+ const AVPixFmtDescriptor* desc = av_pix_fmt_desc_get(inlink->format);
+ const AVPixFmtDescriptor* odesc = av_pix_fmt_desc_get(outlink->format);
+
+
+ if (av_frame_is_writable(in)) {
+ out = in;
+ } else {
+ out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+ if (!out) {
+ av_frame_free(&in);
+ return AVERROR(ENOMEM);
+ }
+ av_frame_copy_props(out, in);
+ }
+ /* input and output transfer will be linear */
+ if (in->color_trc == AVCOL_TRC_UNSPECIFIED) {
+ av_log(s, AV_LOG_WARNING, "Untagged transfer, assuming linear light\n");
+ out->color_trc = AVCOL_TRC_LINEAR;
+ } else if (in->color_trc != AVCOL_TRC_LINEAR) {
+ av_log(s, AV_LOG_WARNING, "Tonemapping works on linear light only\n");
+ }
+
+ td.in = in;
+ td.out = out;
+ td.desc = desc;
+ td.odesc = odesc;
+
+ ctx->internal->execute(ctx, convert_frame, &td, NULL, FFMIN(outlink->h, ff_filter_get_nb_threads(ctx)));
+ compute_correction(s, &td);
+ ctx->internal->execute(ctx, correct_frame, &td, NULL, FFMIN(outlink->h, ff_filter_get_nb_threads(ctx)));
+
+ if (desc->flags & AV_PIX_FMT_FLAG_ALPHA && desc->flags & AV_PIX_FMT_FLAG_ALPHA) {
+ av_image_copy_plane(out->data[3], out->linesize[3],
+ in->data[3], in->linesize[3],
+ out->linesize[3], outlink->h);
+ } else if (desc->flags & AV_PIX_FMT_FLAG_ALPHA) {
+ for (int y = 0; y < out->height; y++) {
+ for (int x = 0; x < out->width; x++) {
+ AV_WN32(out->data[3] + x * desc->comp[3].step + y * out->linesize[3],
+ av_float2int(1.0f));
+ }
+ }
+ }
+
+ if (in != out)
+ av_frame_free(&in);
+ return ff_filter_frame(outlink, out);
+}
+
+static const AVFilterPad grayworld_inputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .filter_frame = filter_frame,
+ .config_props = config_input,
+ },
+ {NULL} };
+
+static const AVFilterPad grayworld_outputs[] = {
+ {
+ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ },
+ {NULL} };
+
+const AVFilter ff_vf_grayworld = {
+ .name = "grayworld",
+ .description = NULL_IF_CONFIG_SMALL("Adjust white balance using LAB gray world algorithm"),
+ .priv_size = sizeof(GrayWorldContext),
+ .priv_class = &grayworld_class,
+ .query_formats = query_formats,
+ .inputs = grayworld_inputs,
+ .outputs = grayworld_outputs,
+ .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
+ .process_command = ff_filter_process_command,
+ .uninit = uninit,
+};
--
2.17.1
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