diff options
author | Paul Buxton <paulbuxton.mail@googlemail.com> | 2021-08-28 16:17:27 +0100 |
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committer | Paul B Mahol <onemda@gmail.com> | 2021-08-29 13:31:37 +0200 |
commit | e07ada3dac9c2e37c425741ee512676625d677ba (patch) | |
tree | 05a54628706bc15b252d745ccf7c72203b8e2f23 /libavfilter/vf_grayworld.c | |
parent | 02fcd485f91e468638198ba05847af514ae58df9 (diff) |
avfilter: add grayworld video filter
Implements a gray world color correction algorithm
using a log scale LAB colorspace.
Signed-off-by: Paul Buxton <paulbuxton.mail@googlemail.com>
Signed-off-by: Paul B Mahol <onemda@gmail.com>
Diffstat (limited to 'libavfilter/vf_grayworld.c')
-rw-r--r-- | libavfilter/vf_grayworld.c | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/libavfilter/vf_grayworld.c b/libavfilter/vf_grayworld.c new file mode 100644 index 0000000000..fd424527e2 --- /dev/null +++ b/libavfilter/vf_grayworld.c @@ -0,0 +1,337 @@ +/* + * 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 "avfilter.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; +} ThreadData; + +typedef struct GrayWorldContext { + const AVClass *class; + float *tmpplab; + int *line_count_pels; + float *line_sum; +} 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); + +static int query_formats(AVFilterContext *ctx) +{ + static const enum AVPixelFormat pix_fmts[] = { + AV_PIX_FMT_GBRPF32, AV_PIX_FMT_GBRAPF32, + AV_PIX_FMT_NONE, + }; + return ff_set_common_formats_from_list(ctx, pix_fmts); +} + +static void apply_matrix(const float matrix[3][3], const float input[3], float output[3]) +{ + output[0] = matrix[0][0] * input[0] + matrix[0][1] * input[1] + matrix[0][2] * input[2]; + output[1] = matrix[1][0] * input[0] + matrix[1][1] * input[1] + matrix[1][2] * input[2]; + output[2] = matrix[2][0] * input[0] + matrix[2][1] * input[1] + matrix[2][2] * input[2]; +} + +static const float lms2lab[3][3] = { + {0.5774, 0.5774, 0.5774}, + {0.40825, 0.40825, -0.816458}, + {0.707, -0.707, 0} +}; + +static const float lab2lms[3][3] = { + {0.57735, 0.40825, 0.707}, + {0.57735, 0.40825, -0.707}, + {0.57735, -0.8165, 0} +}; + +static const float rgb2lms[3][3] = { + {0.3811, 0.5783, 0.0402}, + {0.1967, 0.7244, 0.0782}, + {0.0241, 0.1288, 0.8444} +}; + +static const 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 + */ +static void rgb2lab(const float rgb[3], float lab[3]) +{ + float lms[3]; + + apply_matrix(rgb2lms, rgb, lms); + lms[0] = lms[0] > 0.f ? logf(lms[0]) : -1024.f; + lms[1] = lms[1] > 0.f ? logf(lms[1]) : -1024.f; + lms[2] = lms[2] > 0.f ? logf(lms[2]) : -1024.f; + 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 + */ +static void lab2rgb(const float lab[3], float rgb[3]) +{ + float lms[3]; + + apply_matrix(lab2lms, lab, lms); + lms[0] = expf(lms[0]); + lms[1] = expf(lms[1]); + lms[2] = expf(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], lab[3]; + + for (int i = slice_start; i < slice_end; i++) { + float *b_in_row = (float *)(in->data[1] + i * in->linesize[1]); + float *g_in_row = (float *)(in->data[0] + i * in->linesize[0]); + float *r_in_row = (float *)(in->data[2] + i * in->linesize[2]); + float *acur = s->tmpplab + i * outlink->w + outlink->w * outlink->h; + float *bcur = s->tmpplab + i * outlink->w + 2 * outlink->w * outlink->h; + float *lcur = s->tmpplab + i * outlink->w; + + s->line_sum[i] = 0.f; + s->line_sum[i + outlink->h] = 0.f; + s->line_count_pels[i] = 0; + + for (int j = 0; j < outlink->w; j++) { + rgb[0] = r_in_row[j]; + rgb[1] = g_in_row[j]; + rgb[2] = b_in_row[j]; + rgb2lab(rgb, lab); + *(lcur++) = lab[0]; + *(acur++) = lab[1]; + *(bcur++) = lab[2]; + s->line_sum[i] += lab[1]; + s->line_sum[i + outlink->h] += lab[2]; + s->line_count_pels[i]++; + } + } + return 0; +} + +/** + * Sum the channel totals and compute the mean for each channel + * + * @param s Frame context + * @param td thread data + */ +static void compute_correction(GrayWorldContext *s, ThreadData *td) +{ + float asum = 0.f, bsum = 0.f; + int pixels = 0; + + for (int y = 0; y < td->out->height; y++) { + asum += s->line_sum[y]; + bsum += s->line_sum[y + td->out->height]; + pixels += s->line_count_pels[y]; + } + + td->a_avg = asum / pixels; + td->b_avg = bsum / pixels; +} + +/** + * Subtract the mean 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], 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->tmpplab + i * outlink->w; + float *acur = s->tmpplab + i * outlink->w + outlink->w * outlink->h; + float *bcur = s->tmpplab + i * outlink->w + 2 * outlink->w * outlink->h; + + 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] = rgb[0]; + g_out_row[j] = rgb[1]; + b_out_row[j] = rgb[2]; + } + } + return 0; +} + +static int config_input(AVFilterLink *inlink) +{ + GrayWorldContext *s = inlink->dst->priv; + + FF_ALLOC_TYPED_ARRAY(s->tmpplab, inlink->h * inlink->w * 3); + FF_ALLOC_TYPED_ARRAY(s->line_count_pels, inlink->h); + FF_ALLOC_TYPED_ARRAY(s->line_sum, inlink->h * 2); + if (!s->tmpplab || !s->line_count_pels || !s->line_sum) + return AVERROR(ENOMEM); + + return 0; +} + +static av_cold void uninit(AVFilterContext *ctx) +{ + GrayWorldContext *s = ctx->priv; + + av_freep(&s->tmpplab); + av_freep(&s->line_count_pels); + av_freep(&s->line_sum); +} + +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; + + 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, "Gray world color correction works on linear light only.\n"); + } + + td.in = in; + td.out = out; + + ff_filter_execute(ctx, convert_frame, &td, NULL, FFMIN(outlink->h, ff_filter_get_nb_threads(ctx))); + compute_correction(s, &td); + ff_filter_execute(ctx, correct_frame, &td, NULL, FFMIN(outlink->h, ff_filter_get_nb_threads(ctx))); + + if (in != out) { + av_image_copy_plane(out->data[3], out->linesize[3], + in->data[3], in->linesize[3], outlink->w * 4, outlink->h); + 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, + } +}; + +static const AVFilterPad grayworld_outputs[] = { + { + .name = "default", + .type = AVMEDIA_TYPE_VIDEO, + } +}; + +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, + FILTER_INPUTS(grayworld_inputs), + FILTER_OUTPUTS(grayworld_outputs), + .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS, + .uninit = uninit, +}; 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