2 * Copyright (c) 2013 Clément Bœsch
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "libavutil/opt.h"
22 #include "libavutil/eval.h"
23 #include "libavutil/avassert.h"
31 struct keypoint *next;
39 char *comp_points_str[NB_COMP];
40 uint8_t graph[NB_COMP][256];
43 #define OFFSET(x) offsetof(CurvesContext, x)
44 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
45 static const AVOption curves_options[] = {
46 { "red", "set red points coordinates", OFFSET(comp_points_str[0]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
47 { "r", "set red points coordinates", OFFSET(comp_points_str[0]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
48 { "green", "set green points coordinates", OFFSET(comp_points_str[1]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
49 { "g", "set green points coordinates", OFFSET(comp_points_str[1]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
50 { "blue", "set blue points coordinates", OFFSET(comp_points_str[2]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
51 { "b", "set blue points coordinates", OFFSET(comp_points_str[2]), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
52 { "preset", "select a color curves preset", OFFSET(preset), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
56 AVFILTER_DEFINE_CLASS(curves);
63 } curves_presets[] = { {
65 "0/1 0.129/1 0.466/0.498 0.725/0 1/0",
66 "0/1 0.109/1 0.301/0.498 0.517/0 1/0",
67 "0/1 0.098/1 0.235/0.498 0.423/0 1/0",
70 "0.25/0.156 0.501/0.501 0.686/0.745",
71 "0.25/0.188 0.38/0.501 0.745/0.815 1/0.815",
72 "0.231/0.094 0.709/0.874",
74 "darker", "0.5/0.4", "0.5/0.4", "0.5/0.4",
77 "0.149/0.066 0.831/0.905 0.905/0.98",
78 "0.149/0.066 0.831/0.905 0.905/0.98",
79 "0.149/0.066 0.831/0.905 0.905/0.98",
81 "lighter", "0.4/0.5", "0.4/0.5", "0.4/0.5",
84 "0.305/0.286 0.694/0.713",
85 "0.305/0.286 0.694/0.713",
86 "0.305/0.286 0.694/0.713",
89 "0.286/0.219 0.639/0.643",
90 "0.286/0.219 0.639/0.643",
91 "0.286/0.219 0.639/0.643",
93 "negative", "0/1 1/0", "0/1 1/0", "0/1 1/0",
96 "0.301/0.196 0.592/0.6 0.686/0.737",
97 "0.301/0.196 0.592/0.6 0.686/0.737",
98 "0.301/0.196 0.592/0.6 0.686/0.737",
101 "0/0.11 0.42/0.51 1/0.95",
103 "0/0.22 0.49/0.44 1/0.8",
107 static struct keypoint *make_point(double x, double y, struct keypoint *next)
109 struct keypoint *point = av_mallocz(sizeof(*point));
119 static int parse_points_str(AVFilterContext *ctx, struct keypoint **points, const char *s)
121 char *p = (char *)s; // strtod won't alter the string
122 struct keypoint *last = NULL;
124 /* construct a linked list based on the key points string */
126 struct keypoint *point = make_point(0, 0, NULL);
128 return AVERROR(ENOMEM);
129 point->x = av_strtod(p, &p); if (p && *p) p++;
130 point->y = av_strtod(p, &p); if (p && *p) p++;
131 if (point->x < 0 || point->x > 1 || point->y < 0 || point->y > 1) {
132 av_log(ctx, AV_LOG_ERROR, "Invalid key point coordinates (%f;%f), "
133 "x and y must be in the [0;1] range.\n", point->x, point->y);
134 return AVERROR(EINVAL);
139 if ((int)(last->x * 255) >= (int)(point->x * 255)) {
140 av_log(ctx, AV_LOG_ERROR, "Key point coordinates (%f;%f) "
141 "and (%f;%f) are too close from each other or not "
142 "strictly increasing on the x-axis\n",
143 last->x, last->y, point->x, point->y);
144 return AVERROR(EINVAL);
151 /* auto insert first key point if missing at x=0 */
153 last = make_point(0, 0, NULL);
155 return AVERROR(ENOMEM);
156 last->x = last->y = 0;
158 } else if ((*points)->x != 0.) {
159 struct keypoint *newfirst = make_point(0, 0, *points);
161 return AVERROR(ENOMEM);
167 /* auto insert last key point if missing at x=1 */
169 struct keypoint *point = make_point(1, 1, NULL);
171 return AVERROR(ENOMEM);
178 static int get_nb_points(const struct keypoint *d)
189 * Natural cubic spline interpolation
190 * Finding curves using Cubic Splines notes by Steven Rauch and John Stockie.
191 * @see http://people.math.sfu.ca/~stockie/teaching/macm316/notes/splines.pdf
193 static int interpolate(AVFilterContext *ctx, uint8_t *y, const struct keypoint *points)
196 const struct keypoint *point;
199 int n = get_nb_points(points); // number of splines
201 double (*matrix)[3] = av_calloc(n, sizeof(*matrix));
202 double *h = av_malloc((n - 1) * sizeof(*h));
203 double *r = av_calloc(n, sizeof(*r));
205 if (!matrix || !h || !r) {
206 ret = AVERROR(ENOMEM);
210 /* h(i) = x(i+1) - x(i) */
212 for (point = points; point; point = point->next) {
214 h[i] = point->x - xprev;
219 /* right-side of the polynomials, will be modified to contains the solution */
221 for (i = 1; i < n - 1; i++) {
222 double yp = point->y,
224 yn = point->next->next->y;
225 r[i] = 6 * ((yn-yc)/h[i] - (yc-yp)/h[i-1]);
229 #define B 0 /* sub diagonal (below main) */
230 #define M 1 /* main diagonal (center) */
231 #define A 2 /* sup diagonal (above main) */
233 /* left side of the polynomials into a tridiagonal matrix. */
234 matrix[0][M] = matrix[n - 1][M] = 1;
235 for (i = 1; i < n - 1; i++) {
236 matrix[i][B] = h[i-1];
237 matrix[i][M] = 2 * (h[i-1] + h[i]);
241 /* tridiagonal solving of the linear system */
242 for (i = 1; i < n; i++) {
243 double den = matrix[i][M] - matrix[i][B] * matrix[i-1][A];
244 double k = den ? 1./den : 1.;
246 r[i] = (r[i] - matrix[i][B] * r[i - 1]) * k;
248 for (i = n - 2; i >= 0; i--)
249 r[i] = r[i] - matrix[i][A] * r[i + 1];
251 /* compute the graph with x=[0..255] */
254 av_assert0(point->next); // always at least 2 key points
255 while (point->next) {
256 double yc = point->y;
257 double yn = point->next->y;
260 double b = (yn-yc)/h[i] - h[i]*r[i]/2. - h[i]*(r[i+1]-r[i])/6.;
261 double c = r[i] / 2.;
262 double d = (r[i+1] - r[i]) / (6.*h[i]);
265 int x_start = point->x * 255;
266 int x_end = point->next->x * 255;
268 av_assert0(x_start >= 0 && x_start <= 255 &&
269 x_end >= 0 && x_end <= 255);
271 for (x = x_start; x <= x_end; x++) {
272 double xx = (x - x_start) * 1/255.;
273 double yy = a + b*xx + c*xx*xx + d*xx*xx*xx;
274 y[x] = av_clipf(yy, 0, 1) * 255;
275 av_log(ctx, AV_LOG_DEBUG, "f(%f)=%f -> y[%d]=%d\n", xx, yy, x, y[x]);
289 static av_cold int init(AVFilterContext *ctx, const char *args)
292 CurvesContext *curves = ctx->priv;
293 struct keypoint *comp_points[NB_COMP] = {0};
295 if (curves->preset) {
296 char **pts = curves->comp_points_str;
297 if (pts[0] || pts[1] || pts[2]) {
298 av_log(ctx, AV_LOG_ERROR, "It is not possible to mix a preset "
299 "with explicit points placements\n");
300 return AVERROR(EINVAL);
302 for (i = 0; i < FF_ARRAY_ELEMS(curves_presets); i++) {
303 if (!strcmp(curves->preset, curves_presets[i].name)) {
304 pts[0] = av_strdup(curves_presets[i].r);
305 pts[1] = av_strdup(curves_presets[i].g);
306 pts[2] = av_strdup(curves_presets[i].b);
307 if (!pts[0] || !pts[1] || !pts[2])
308 return AVERROR(ENOMEM);
312 if (i == FF_ARRAY_ELEMS(curves_presets)) {
313 av_log(ctx, AV_LOG_ERROR, "Preset '%s' not found. Available presets:",
315 for (i = 0; i < FF_ARRAY_ELEMS(curves_presets); i++)
316 av_log(ctx, AV_LOG_ERROR, " %s", curves_presets[i].name);
317 av_log(ctx, AV_LOG_ERROR, ".\n");
318 return AVERROR(EINVAL);
322 for (i = 0; i < NB_COMP; i++) {
323 ret = parse_points_str(ctx, comp_points + i, curves->comp_points_str[i]);
326 ret = interpolate(ctx, curves->graph[i], comp_points[i]);
331 if (av_log_get_level() >= AV_LOG_VERBOSE) {
332 for (i = 0; i < NB_COMP; i++) {
333 struct keypoint *point = comp_points[i];
334 av_log(ctx, AV_LOG_VERBOSE, "#%d points:", i);
336 av_log(ctx, AV_LOG_VERBOSE, " (%f;%f)", point->x, point->y);
339 av_log(ctx, AV_LOG_VERBOSE, "\n");
340 av_log(ctx, AV_LOG_VERBOSE, "#%d values:", i);
341 for (j = 0; j < 256; j++)
342 av_log(ctx, AV_LOG_VERBOSE, " %02X", curves->graph[i][j]);
343 av_log(ctx, AV_LOG_VERBOSE, "\n");
347 for (i = 0; i < NB_COMP; i++) {
348 struct keypoint *point = comp_points[i];
350 struct keypoint *next = point->next;
359 static int query_formats(AVFilterContext *ctx)
361 static const enum AVPixelFormat pix_fmts[] = {AV_PIX_FMT_RGB24, AV_PIX_FMT_NONE};
362 ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
366 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
368 int x, y, i, direct = 0;
369 AVFilterContext *ctx = inlink->dst;
370 CurvesContext *curves = ctx->priv;
371 AVFilterLink *outlink = inlink->dst->outputs[0];
376 if (av_frame_is_writable(in)) {
380 out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
383 return AVERROR(ENOMEM);
385 av_frame_copy_props(out, in);
391 for (y = 0; y < inlink->h; y++) {
393 const uint8_t *srcp = src;
395 for (x = 0; x < inlink->w; x++)
396 for (i = 0; i < NB_COMP; i++, dstp++, srcp++)
397 *dstp = curves->graph[i][*srcp];
398 dst += out->linesize[0];
399 src += in ->linesize[0];
405 return ff_filter_frame(outlink, out);
408 static const AVFilterPad curves_inputs[] = {
411 .type = AVMEDIA_TYPE_VIDEO,
412 .filter_frame = filter_frame,
417 static const AVFilterPad curves_outputs[] = {
420 .type = AVMEDIA_TYPE_VIDEO,
425 static const char *const shorthand[] = { "preset", NULL };
427 AVFilter avfilter_vf_curves = {
429 .description = NULL_IF_CONFIG_SMALL("Adjust components curves."),
430 .priv_size = sizeof(CurvesContext),
432 .query_formats = query_formats,
433 .inputs = curves_inputs,
434 .outputs = curves_outputs,
435 .priv_class = &curves_class,
436 .shorthand = shorthand,