| 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/opt.h" |
| 32 | #include "libavutil/pixdesc.h" |
| 33 | |
| 34 | #include "avfilter.h" |
| 35 | #include "drawutils.h" |
| 36 | #include "formats.h" |
| 37 | #include "internal.h" |
| 38 | #include "video.h" |
| 39 | |
| 40 | // #define DEBUG |
| 41 | |
| 42 | // Linear Congruential Generator, see "Numerical Recipes" |
| 43 | #define LCG_A 4096 |
| 44 | #define LCG_C 150889 |
| 45 | #define LCG_M 714025 |
| 46 | #define LCG(x) (((x) * LCG_A + LCG_C) % LCG_M) |
| 47 | #define LCG_SEED 739187 |
| 48 | |
| 49 | enum HisteqAntibanding { |
| 50 | HISTEQ_ANTIBANDING_NONE = 0, |
| 51 | HISTEQ_ANTIBANDING_WEAK = 1, |
| 52 | HISTEQ_ANTIBANDING_STRONG = 2, |
| 53 | HISTEQ_ANTIBANDING_NB, |
| 54 | }; |
| 55 | |
| 56 | typedef struct { |
| 57 | const AVClass *class; |
| 58 | float strength; |
| 59 | float intensity; |
| 60 | enum HisteqAntibanding antibanding; |
| 61 | int in_histogram [256]; ///< input histogram |
| 62 | int out_histogram[256]; ///< output histogram |
| 63 | int LUT[256]; ///< lookup table derived from histogram[] |
| 64 | uint8_t rgba_map[4]; ///< components position |
| 65 | int bpp; ///< bytes per pixel |
| 66 | } HisteqContext; |
| 67 | |
| 68 | #define OFFSET(x) offsetof(HisteqContext, x) |
| 69 | #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM |
| 70 | #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit } |
| 71 | |
| 72 | static const AVOption histeq_options[] = { |
| 73 | { "strength", "set the strength", OFFSET(strength), AV_OPT_TYPE_FLOAT, {.dbl=0.2}, 0, 1, FLAGS }, |
| 74 | { "intensity", "set the intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.21}, 0, 1, FLAGS }, |
| 75 | { "antibanding", "set the antibanding level", OFFSET(antibanding), AV_OPT_TYPE_INT, {.i64=HISTEQ_ANTIBANDING_NONE}, 0, HISTEQ_ANTIBANDING_NB-1, FLAGS, "antibanding" }, |
| 76 | CONST("none", "apply no antibanding", HISTEQ_ANTIBANDING_NONE, "antibanding"), |
| 77 | CONST("weak", "apply weak antibanding", HISTEQ_ANTIBANDING_WEAK, "antibanding"), |
| 78 | CONST("strong", "apply strong antibanding", HISTEQ_ANTIBANDING_STRONG, "antibanding"), |
| 79 | { NULL } |
| 80 | }; |
| 81 | |
| 82 | AVFILTER_DEFINE_CLASS(histeq); |
| 83 | |
| 84 | static av_cold int init(AVFilterContext *ctx) |
| 85 | { |
| 86 | HisteqContext *histeq = ctx->priv; |
| 87 | |
| 88 | av_log(ctx, AV_LOG_VERBOSE, |
| 89 | "strength:%0.3f intensity:%0.3f antibanding:%d\n", |
| 90 | histeq->strength, histeq->intensity, histeq->antibanding); |
| 91 | |
| 92 | return 0; |
| 93 | } |
| 94 | |
| 95 | static int query_formats(AVFilterContext *ctx) |
| 96 | { |
| 97 | static const enum PixelFormat pix_fmts[] = { |
| 98 | AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA, |
| 99 | AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24, |
| 100 | AV_PIX_FMT_NONE |
| 101 | }; |
| 102 | |
| 103 | ff_set_common_formats(ctx, ff_make_format_list(pix_fmts)); |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | static int config_input(AVFilterLink *inlink) |
| 108 | { |
| 109 | AVFilterContext *ctx = inlink->dst; |
| 110 | HisteqContext *histeq = ctx->priv; |
| 111 | const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format); |
| 112 | |
| 113 | histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8; |
| 114 | ff_fill_rgba_map(histeq->rgba_map, inlink->format); |
| 115 | |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | #define R 0 |
| 120 | #define G 1 |
| 121 | #define B 2 |
| 122 | #define A 3 |
| 123 | |
| 124 | #define GET_RGB_VALUES(r, g, b, src, map) do { \ |
| 125 | r = src[x + map[R]]; \ |
| 126 | g = src[x + map[G]]; \ |
| 127 | b = src[x + map[B]]; \ |
| 128 | } while (0) |
| 129 | |
| 130 | static int filter_frame(AVFilterLink *inlink, AVFrame *inpic) |
| 131 | { |
| 132 | AVFilterContext *ctx = inlink->dst; |
| 133 | HisteqContext *histeq = ctx->priv; |
| 134 | AVFilterLink *outlink = ctx->outputs[0]; |
| 135 | int strength = histeq->strength * 1000; |
| 136 | int intensity = histeq->intensity * 1000; |
| 137 | int x, y, i, luthi, lutlo, lut, luma, oluma, m; |
| 138 | AVFrame *outpic; |
| 139 | unsigned int r, g, b, jran; |
| 140 | uint8_t *src, *dst; |
| 141 | |
| 142 | outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h); |
| 143 | if (!outpic) { |
| 144 | av_frame_free(&inpic); |
| 145 | return AVERROR(ENOMEM); |
| 146 | } |
| 147 | av_frame_copy_props(outpic, inpic); |
| 148 | |
| 149 | /* Seed random generator for antibanding. */ |
| 150 | jran = LCG_SEED; |
| 151 | |
| 152 | /* Calculate and store the luminance and calculate the global histogram |
| 153 | based on the luminance. */ |
| 154 | memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram)); |
| 155 | src = inpic->data[0]; |
| 156 | dst = outpic->data[0]; |
| 157 | for (y = 0; y < inlink->h; y++) { |
| 158 | for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) { |
| 159 | GET_RGB_VALUES(r, g, b, src, histeq->rgba_map); |
| 160 | luma = (55 * r + 182 * g + 19 * b) >> 8; |
| 161 | dst[x + histeq->rgba_map[A]] = luma; |
| 162 | histeq->in_histogram[luma]++; |
| 163 | } |
| 164 | src += inpic->linesize[0]; |
| 165 | dst += outpic->linesize[0]; |
| 166 | } |
| 167 | |
| 168 | #ifdef DEBUG |
| 169 | for (x = 0; x < 256; x++) |
| 170 | av_dlog(ctx, "in[%d]: %u\n", x, histeq->in_histogram[x]); |
| 171 | #endif |
| 172 | |
| 173 | /* Calculate the lookup table. */ |
| 174 | histeq->LUT[0] = histeq->in_histogram[0]; |
| 175 | /* Accumulate */ |
| 176 | for (x = 1; x < 256; x++) |
| 177 | histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x]; |
| 178 | |
| 179 | /* Normalize */ |
| 180 | for (x = 0; x < 256; x++) |
| 181 | histeq->LUT[x] = (histeq->LUT[x] * intensity) / (inlink->h * inlink->w); |
| 182 | |
| 183 | /* Adjust the LUT based on the selected strength. This is an alpha |
| 184 | mix of the calculated LUT and a linear LUT with gain 1. */ |
| 185 | for (x = 0; x < 256; x++) |
| 186 | histeq->LUT[x] = (strength * histeq->LUT[x]) / 255 + |
| 187 | ((255 - strength) * x) / 255; |
| 188 | |
| 189 | /* Output the equalized frame. */ |
| 190 | memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram)); |
| 191 | |
| 192 | src = inpic->data[0]; |
| 193 | dst = outpic->data[0]; |
| 194 | for (y = 0; y < inlink->h; y++) { |
| 195 | for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) { |
| 196 | luma = dst[x + histeq->rgba_map[A]]; |
| 197 | if (luma == 0) { |
| 198 | for (i = 0; i < histeq->bpp; ++i) |
| 199 | dst[x + i] = 0; |
| 200 | histeq->out_histogram[0]++; |
| 201 | } else { |
| 202 | lut = histeq->LUT[luma]; |
| 203 | if (histeq->antibanding != HISTEQ_ANTIBANDING_NONE) { |
| 204 | if (luma > 0) { |
| 205 | lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ? |
| 206 | (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 : |
| 207 | histeq->LUT[luma - 1]; |
| 208 | } else |
| 209 | lutlo = lut; |
| 210 | |
| 211 | if (luma < 255) { |
| 212 | luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ? |
| 213 | (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 : |
| 214 | histeq->LUT[luma + 1]; |
| 215 | } else |
| 216 | luthi = lut; |
| 217 | |
| 218 | if (lutlo != luthi) { |
| 219 | jran = LCG(jran); |
| 220 | lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M; |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | GET_RGB_VALUES(r, g, b, src, histeq->rgba_map); |
| 225 | if (((m = FFMAX3(r, g, b)) * lut) / luma > 255) { |
| 226 | r = (r * 255) / m; |
| 227 | g = (g * 255) / m; |
| 228 | b = (b * 255) / m; |
| 229 | } else { |
| 230 | r = (r * lut) / luma; |
| 231 | g = (g * lut) / luma; |
| 232 | b = (b * lut) / luma; |
| 233 | } |
| 234 | dst[x + histeq->rgba_map[R]] = r; |
| 235 | dst[x + histeq->rgba_map[G]] = g; |
| 236 | dst[x + histeq->rgba_map[B]] = b; |
| 237 | oluma = av_clip_uint8((55 * r + 182 * g + 19 * b) >> 8); |
| 238 | histeq->out_histogram[oluma]++; |
| 239 | } |
| 240 | } |
| 241 | src += inpic->linesize[0]; |
| 242 | dst += outpic->linesize[0]; |
| 243 | } |
| 244 | #ifdef DEBUG |
| 245 | for (x = 0; x < 256; x++) |
| 246 | av_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]); |
| 247 | #endif |
| 248 | |
| 249 | av_frame_free(&inpic); |
| 250 | return ff_filter_frame(outlink, outpic); |
| 251 | } |
| 252 | |
| 253 | static const AVFilterPad histeq_inputs[] = { |
| 254 | { |
| 255 | .name = "default", |
| 256 | .type = AVMEDIA_TYPE_VIDEO, |
| 257 | .config_props = config_input, |
| 258 | .filter_frame = filter_frame, |
| 259 | }, |
| 260 | { NULL } |
| 261 | }; |
| 262 | |
| 263 | static const AVFilterPad histeq_outputs[] = { |
| 264 | { |
| 265 | .name = "default", |
| 266 | .type = AVMEDIA_TYPE_VIDEO, |
| 267 | }, |
| 268 | { NULL } |
| 269 | }; |
| 270 | |
| 271 | AVFilter ff_vf_histeq = { |
| 272 | .name = "histeq", |
| 273 | .description = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."), |
| 274 | .priv_size = sizeof(HisteqContext), |
| 275 | .init = init, |
| 276 | .query_formats = query_formats, |
| 277 | .inputs = histeq_inputs, |
| 278 | .outputs = histeq_outputs, |
| 279 | .priv_class = &histeq_class, |
| 280 | .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, |
| 281 | }; |