| /* |
| * 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/mem.h" |
| |
| #include "avfilter.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 { |
| float *tmpplab; |
| int *line_count_pels; |
| float *line_sum; |
| } GrayWorldContext; |
| |
| 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, |
| } |
| }; |
| |
| const AVFilter ff_vf_grayworld = { |
| .name = "grayworld", |
| .description = NULL_IF_CONFIG_SMALL("Adjust white balance using LAB gray world algorithm"), |
| .priv_size = sizeof(GrayWorldContext), |
| FILTER_INPUTS(grayworld_inputs), |
| FILTER_OUTPUTS(ff_video_default_filterpad), |
| FILTER_PIXFMTS(AV_PIX_FMT_GBRPF32, AV_PIX_FMT_GBRAPF32), |
| .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS, |
| .uninit = uninit, |
| }; |