FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavfilter/vf_histeq.c
Date: 2022-11-26 13:19:19
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1 /*
2 * Copyright (c) 2012 Jeremy Tran
3 * Copyright (c) 2001 Donald A. Graft
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 */
21
22 /**
23 * @file
24 * Histogram equalization filter, based on the VirtualDub filter by
25 * Donald A. Graft <neuron2 AT home DOT com>.
26 * Implements global automatic contrast adjustment by means of
27 * histogram equalization.
28 */
29
30 #include "libavutil/common.h"
31 #include "libavutil/internal.h"
32 #include "libavutil/opt.h"
33 #include "libavutil/pixdesc.h"
34
35 #include "avfilter.h"
36 #include "drawutils.h"
37 #include "formats.h"
38 #include "internal.h"
39 #include "video.h"
40
41 // #define DEBUG
42
43 // Linear Congruential Generator, see "Numerical Recipes"
44 #define LCG_A 4096
45 #define LCG_C 150889
46 #define LCG_M 714025
47 #define LCG(x) (((x) * LCG_A + LCG_C) % LCG_M)
48 #define LCG_SEED 739187
49
50 enum HisteqAntibanding {
51 HISTEQ_ANTIBANDING_NONE = 0,
52 HISTEQ_ANTIBANDING_WEAK = 1,
53 HISTEQ_ANTIBANDING_STRONG = 2,
54 HISTEQ_ANTIBANDING_NB,
55 };
56
57 typedef struct HisteqContext {
58 const AVClass *class;
59 float strength;
60 float intensity;
61 int antibanding; ///< HisteqAntibanding
62 int in_histogram [256]; ///< input histogram
63 int out_histogram[256]; ///< output histogram
64 int LUT[256]; ///< lookup table derived from histogram[]
65 uint8_t rgba_map[4]; ///< components position
66 int bpp; ///< bytes per pixel
67 } HisteqContext;
68
69 #define OFFSET(x) offsetof(HisteqContext, x)
70 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
71 #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }
72
73 static const AVOption histeq_options[] = {
74 { "strength", "set the strength", OFFSET(strength), AV_OPT_TYPE_FLOAT, {.dbl=0.2}, 0, 1, FLAGS },
75 { "intensity", "set the intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.21}, 0, 1, FLAGS },
76 { "antibanding", "set the antibanding level", OFFSET(antibanding), AV_OPT_TYPE_INT, {.i64=HISTEQ_ANTIBANDING_NONE}, 0, HISTEQ_ANTIBANDING_NB-1, FLAGS, "antibanding" },
77 CONST("none", "apply no antibanding", HISTEQ_ANTIBANDING_NONE, "antibanding"),
78 CONST("weak", "apply weak antibanding", HISTEQ_ANTIBANDING_WEAK, "antibanding"),
79 CONST("strong", "apply strong antibanding", HISTEQ_ANTIBANDING_STRONG, "antibanding"),
80 { NULL }
81 };
82
83 AVFILTER_DEFINE_CLASS(histeq);
84
85 static av_cold int init(AVFilterContext *ctx)
86 {
87 HisteqContext *histeq = ctx->priv;
88
89 av_log(ctx, AV_LOG_VERBOSE,
90 "strength:%0.3f intensity:%0.3f antibanding:%d\n",
91 histeq->strength, histeq->intensity, histeq->antibanding);
92
93 return 0;
94 }
95
96 static const enum AVPixelFormat pix_fmts[] = {
97 AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA,
98 AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
99 AV_PIX_FMT_NONE
100 };
101
102 static int config_input(AVFilterLink *inlink)
103 {
104 AVFilterContext *ctx = inlink->dst;
105 HisteqContext *histeq = ctx->priv;
106 const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
107
108 histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8;
109 ff_fill_rgba_map(histeq->rgba_map, inlink->format);
110
111 return 0;
112 }
113
114 #define R 0
115 #define G 1
116 #define B 2
117 #define A 3
118
119 #define GET_RGB_VALUES(r, g, b, src, map) do { \
120 r = src[x + map[R]]; \
121 g = src[x + map[G]]; \
122 b = src[x + map[B]]; \
123 } while (0)
124
125 static int filter_frame(AVFilterLink *inlink, AVFrame *inpic)
126 {
127 AVFilterContext *ctx = inlink->dst;
128 HisteqContext *histeq = ctx->priv;
129 AVFilterLink *outlink = ctx->outputs[0];
130 int strength = histeq->strength * 1000;
131 int intensity = histeq->intensity * 1000;
132 int x, y, i, luthi, lutlo, lut, luma, oluma, m;
133 AVFrame *outpic;
134 unsigned int r, g, b, jran;
135 uint8_t *src, *dst;
136
137 outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h);
138 if (!outpic) {
139 av_frame_free(&inpic);
140 return AVERROR(ENOMEM);
141 }
142 av_frame_copy_props(outpic, inpic);
143
144 /* Seed random generator for antibanding. */
145 jran = LCG_SEED;
146
147 /* Calculate and store the luminance and calculate the global histogram
148 based on the luminance. */
149 memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram));
150 src = inpic->data[0];
151 dst = outpic->data[0];
152 for (y = 0; y < inlink->h; y++) {
153 for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
154 GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
155 luma = (55 * r + 182 * g + 19 * b) >> 8;
156 dst[x + histeq->rgba_map[A]] = luma;
157 histeq->in_histogram[luma]++;
158 }
159 src += inpic->linesize[0];
160 dst += outpic->linesize[0];
161 }
162
163 #ifdef DEBUG
164 for (x = 0; x < 256; x++)
165 ff_dlog(ctx, "in[%d]: %u\n", x, histeq->in_histogram[x]);
166 #endif
167
168 /* Calculate the lookup table. */
169 histeq->LUT[0] = histeq->in_histogram[0];
170 /* Accumulate */
171 for (x = 1; x < 256; x++)
172 histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x];
173
174 /* Normalize */
175 for (x = 0; x < 256; x++)
176 histeq->LUT[x] = (histeq->LUT[x] * intensity) / (inlink->h * inlink->w);
177
178 /* Adjust the LUT based on the selected strength. This is an alpha
179 mix of the calculated LUT and a linear LUT with gain 1. */
180 for (x = 0; x < 256; x++)
181 histeq->LUT[x] = (strength * histeq->LUT[x]) / 255 +
182 ((255 - strength) * x) / 255;
183
184 /* Output the equalized frame. */
185 memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram));
186
187 src = inpic->data[0];
188 dst = outpic->data[0];
189 for (y = 0; y < inlink->h; y++) {
190 for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
191 luma = dst[x + histeq->rgba_map[A]];
192 if (luma == 0) {
193 for (i = 0; i < histeq->bpp; ++i)
194 dst[x + i] = 0;
195 histeq->out_histogram[0]++;
196 } else {
197 lut = histeq->LUT[luma];
198 if (histeq->antibanding != HISTEQ_ANTIBANDING_NONE) {
199 if (luma > 0) {
200 lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ?
201 (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 :
202 histeq->LUT[luma - 1];
203 } else
204 lutlo = lut;
205
206 if (luma < 255) {
207 luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ?
208 (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 :
209 histeq->LUT[luma + 1];
210 } else
211 luthi = lut;
212
213 if (lutlo != luthi) {
214 jran = LCG(jran);
215 lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M;
216 }
217 }
218
219 GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
220 if (((m = FFMAX3(r, g, b)) * lut) / luma > 255) {
221 r = (r * 255) / m;
222 g = (g * 255) / m;
223 b = (b * 255) / m;
224 } else {
225 r = (r * lut) / luma;
226 g = (g * lut) / luma;
227 b = (b * lut) / luma;
228 }
229 dst[x + histeq->rgba_map[R]] = r;
230 dst[x + histeq->rgba_map[G]] = g;
231 dst[x + histeq->rgba_map[B]] = b;
232 oluma = av_clip_uint8((55 * r + 182 * g + 19 * b) >> 8);
233 histeq->out_histogram[oluma]++;
234 }
235 }
236 src += inpic->linesize[0];
237 dst += outpic->linesize[0];
238 }
239 #ifdef DEBUG
240 for (x = 0; x < 256; x++)
241 ff_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]);
242 #endif
243
244 av_frame_free(&inpic);
245 return ff_filter_frame(outlink, outpic);
246 }
247
248 static const AVFilterPad histeq_inputs[] = {
249 {
250 .name = "default",
251 .type = AVMEDIA_TYPE_VIDEO,
252 .config_props = config_input,
253 .filter_frame = filter_frame,
254 },
255 };
256
257 static const AVFilterPad histeq_outputs[] = {
258 {
259 .name = "default",
260 .type = AVMEDIA_TYPE_VIDEO,
261 },
262 };
263
264 const AVFilter ff_vf_histeq = {
265 .name = "histeq",
266 .description = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."),
267 .priv_size = sizeof(HisteqContext),
268 .init = init,
269 FILTER_INPUTS(histeq_inputs),
270 FILTER_OUTPUTS(histeq_outputs),
271 FILTER_PIXFMTS_ARRAY(pix_fmts),
272 .priv_class = &histeq_class,
273 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
274 };
275