[FFmpeg-devel] [PATCH 1/1] Add grayworld color correction filer
Paul B Mahol
onemda at gmail.com
Tue Aug 24 21:28:04 EEST 2021
On Tue, Aug 24, 2021 at 6:58 PM Paul Buxton <paulbuxton.mail at googlemail.com>
wrote:
> 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)
>
alphabetical order
>
> 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
missing word(s)
> +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-$(CONFIG_GRAYWORLD_FILTER) += vf_grayworld.o
>
alphabetical order
> OBJS-$(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;
>
alphabetical order
> 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 *tmppl,
and so on.
> +
> + 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]);
> +
>
no need for several new lines, keep just one empty line.
> +
> +
> +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);
> +}
>
There is now new function to handle this, formats_from_list IIRC.
> +
> +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]);
>
what about using logf, float variant of functions in all cases?
> + 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]);
>
same as above.
> + lms[1] = exp(lms[1]);
> + lms[2] = exp(lms[2]);
> + apply_matrix(lms2rgb, lms, rgb);
> +}
> +
> +/**
> + *
excessive line
>
> + * 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];
> +
> +
>
again.
> +
> + 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;
> +}
> +
> +/**
> + *
excessive line
>
> + * 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;
>
please initialize floats with 0.f;
+ 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.
>
mean, median is something else.
> + *
> + * @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)
>
Please keep style to match with rest of lavfi codebase, thus pointers are
written in another way.
> +{
> + 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;
> +
>
excessive empty line.
> + 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++;
>
IIUC first component is unchanged, thus this step can be skipped completely.
> + 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];
>
This can be written in better way, format is planar, so this can be
dramatically simplified.
> + }
> + }
> + 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));
>
use av_malloc_array. And checking of return value is mandatory.
> +
> + 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));
>
ditto.
> +
> + 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} };
>
{NULL} is not needed any more on master ffmpeg version.
+
> +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,
>
This have been recently changed. Look at other filters for example how it
is done now.
> + .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
> AVFILTER_FLAG_SLICE_THREADS,
> + .process_command = ff_filter_process_command,
>
This one is pointless, since filter have 0 options to configure from
userspace.
> + .uninit = uninit,
> +};
> --
> 2.17.1
>
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