FFmpeg
vf_histeq.c
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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 
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
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 
86 {
87  HisteqContext *histeq = ctx->priv;
88 
90  "strength:%0.3f intensity:%0.3f antibanding:%d\n",
91  histeq->strength, histeq->intensity, histeq->antibanding);
92 
93  return 0;
94 }
95 
97 {
98  static const enum AVPixelFormat pix_fmts[] = {
102  };
103  AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
104  if (!fmts_list)
105  return AVERROR(ENOMEM);
106  return ff_set_common_formats(ctx, fmts_list);
107 }
108 
110 {
111  AVFilterContext *ctx = inlink->dst;
112  HisteqContext *histeq = ctx->priv;
113  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
114 
115  histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8;
116  ff_fill_rgba_map(histeq->rgba_map, inlink->format);
117 
118  return 0;
119 }
120 
121 #define R 0
122 #define G 1
123 #define B 2
124 #define A 3
125 
126 #define GET_RGB_VALUES(r, g, b, src, map) do { \
127  r = src[x + map[R]]; \
128  g = src[x + map[G]]; \
129  b = src[x + map[B]]; \
130 } while (0)
131 
133 {
134  AVFilterContext *ctx = inlink->dst;
135  HisteqContext *histeq = ctx->priv;
136  AVFilterLink *outlink = ctx->outputs[0];
137  int strength = histeq->strength * 1000;
138  int intensity = histeq->intensity * 1000;
139  int x, y, i, luthi, lutlo, lut, luma, oluma, m;
140  AVFrame *outpic;
141  unsigned int r, g, b, jran;
142  uint8_t *src, *dst;
143 
144  outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h);
145  if (!outpic) {
146  av_frame_free(&inpic);
147  return AVERROR(ENOMEM);
148  }
149  av_frame_copy_props(outpic, inpic);
150 
151  /* Seed random generator for antibanding. */
152  jran = LCG_SEED;
153 
154  /* Calculate and store the luminance and calculate the global histogram
155  based on the luminance. */
156  memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram));
157  src = inpic->data[0];
158  dst = outpic->data[0];
159  for (y = 0; y < inlink->h; y++) {
160  for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
161  GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
162  luma = (55 * r + 182 * g + 19 * b) >> 8;
163  dst[x + histeq->rgba_map[A]] = luma;
164  histeq->in_histogram[luma]++;
165  }
166  src += inpic->linesize[0];
167  dst += outpic->linesize[0];
168  }
169 
170 #ifdef DEBUG
171  for (x = 0; x < 256; x++)
172  ff_dlog(ctx, "in[%d]: %u\n", x, histeq->in_histogram[x]);
173 #endif
174 
175  /* Calculate the lookup table. */
176  histeq->LUT[0] = histeq->in_histogram[0];
177  /* Accumulate */
178  for (x = 1; x < 256; x++)
179  histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x];
180 
181  /* Normalize */
182  for (x = 0; x < 256; x++)
183  histeq->LUT[x] = (histeq->LUT[x] * intensity) / (inlink->h * inlink->w);
184 
185  /* Adjust the LUT based on the selected strength. This is an alpha
186  mix of the calculated LUT and a linear LUT with gain 1. */
187  for (x = 0; x < 256; x++)
188  histeq->LUT[x] = (strength * histeq->LUT[x]) / 255 +
189  ((255 - strength) * x) / 255;
190 
191  /* Output the equalized frame. */
192  memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram));
193 
194  src = inpic->data[0];
195  dst = outpic->data[0];
196  for (y = 0; y < inlink->h; y++) {
197  for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
198  luma = dst[x + histeq->rgba_map[A]];
199  if (luma == 0) {
200  for (i = 0; i < histeq->bpp; ++i)
201  dst[x + i] = 0;
202  histeq->out_histogram[0]++;
203  } else {
204  lut = histeq->LUT[luma];
205  if (histeq->antibanding != HISTEQ_ANTIBANDING_NONE) {
206  if (luma > 0) {
207  lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ?
208  (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 :
209  histeq->LUT[luma - 1];
210  } else
211  lutlo = lut;
212 
213  if (luma < 255) {
214  luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ?
215  (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 :
216  histeq->LUT[luma + 1];
217  } else
218  luthi = lut;
219 
220  if (lutlo != luthi) {
221  jran = LCG(jran);
222  lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M;
223  }
224  }
225 
226  GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
227  if (((m = FFMAX3(r, g, b)) * lut) / luma > 255) {
228  r = (r * 255) / m;
229  g = (g * 255) / m;
230  b = (b * 255) / m;
231  } else {
232  r = (r * lut) / luma;
233  g = (g * lut) / luma;
234  b = (b * lut) / luma;
235  }
236  dst[x + histeq->rgba_map[R]] = r;
237  dst[x + histeq->rgba_map[G]] = g;
238  dst[x + histeq->rgba_map[B]] = b;
239  oluma = av_clip_uint8((55 * r + 182 * g + 19 * b) >> 8);
240  histeq->out_histogram[oluma]++;
241  }
242  }
243  src += inpic->linesize[0];
244  dst += outpic->linesize[0];
245  }
246 #ifdef DEBUG
247  for (x = 0; x < 256; x++)
248  ff_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]);
249 #endif
250 
251  av_frame_free(&inpic);
252  return ff_filter_frame(outlink, outpic);
253 }
254 
255 static const AVFilterPad histeq_inputs[] = {
256  {
257  .name = "default",
258  .type = AVMEDIA_TYPE_VIDEO,
259  .config_props = config_input,
260  .filter_frame = filter_frame,
261  },
262  { NULL }
263 };
264 
265 static const AVFilterPad histeq_outputs[] = {
266  {
267  .name = "default",
268  .type = AVMEDIA_TYPE_VIDEO,
269  },
270  { NULL }
271 };
272 
274  .name = "histeq",
275  .description = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."),
276  .priv_size = sizeof(HisteqContext),
277  .init = init,
279  .inputs = histeq_inputs,
280  .outputs = histeq_outputs,
281  .priv_class = &histeq_class,
283 };
static int filter_frame(AVFilterLink *inlink, AVFrame *inpic)
Definition: vf_histeq.c:132
#define NULL
Definition: coverity.c:32
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2522
int out_histogram[256]
output histogram
Definition: vf_histeq.c:63
#define FLAGS
Definition: vf_histeq.c:70
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVOption.
Definition: opt.h:246
Main libavfilter public API header.
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:68
const char * g
Definition: vf_curves.c:115
int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc)
Return the number of bits per pixel used by the pixel format described by pixdesc.
Definition: pixdesc.c:2474
#define LCG_SEED
Definition: vf_histeq.c:48
uint8_t rgba_map[4]
components position
Definition: vf_histeq.c:65
AVFrame * ff_get_video_buffer(AVFilterLink *link, int w, int h)
Request a picture buffer with a specific set of permissions.
Definition: video.c:99
AVFilter ff_vf_histeq
Definition: vf_histeq.c:273
#define src
Definition: vp8dsp.c:254
static const AVOption histeq_options[]
Definition: vf_histeq.c:73
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
#define AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
Some filters support a generic "enable" expression option that can be used to enable or disable a fil...
Definition: avfilter.h:125
const char * name
Pad name.
Definition: internal.h:60
int in_histogram[256]
input histogram
Definition: vf_histeq.c:62
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1093
uint8_t
#define av_cold
Definition: attributes.h:82
AVOptions.
av_frame_free & inpic
Definition: vf_mcdeint.c:278
packed ABGR 8:8:8:8, 32bpp, ABGRABGR...
Definition: pixfmt.h:94
#define ff_dlog(a,...)
float intensity
Definition: vf_histeq.c:60
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:192
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:54
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:569
#define CONST(name, help, val, unit)
Definition: vf_histeq.c:71
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:202
#define LCG(x)
Definition: vf_histeq.c:47
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
packed BGRA 8:8:8:8, 32bpp, BGRABGRA...
Definition: pixfmt.h:95
const char * r
Definition: vf_curves.c:114
void * priv
private data for use by the filter
Definition: avfilter.h:353
packed ARGB 8:8:8:8, 32bpp, ARGBARGB...
Definition: pixfmt.h:92
static int config_input(AVFilterLink *inlink)
Definition: vf_histeq.c:109
packed RGBA 8:8:8:8, 32bpp, RGBARGBA...
Definition: pixfmt.h:93
#define GET_RGB_VALUES(r, g, b, src, map)
Definition: vf_histeq.c:126
common internal API header
#define b
Definition: input.c:41
#define R
Definition: vf_histeq.c:121
AVFormatContext * ctx
Definition: movenc.c:48
static const AVFilterPad histeq_outputs[]
Definition: vf_histeq.c:265
packed RGB 8:8:8, 24bpp, BGRBGR...
Definition: pixfmt.h:69
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
int ff_fill_rgba_map(uint8_t *rgba_map, enum AVPixelFormat pix_fmt)
Definition: drawutils.c:35
#define OFFSET(x)
Definition: vf_histeq.c:69
static av_cold int init(AVFilterContext *ctx)
Definition: vf_histeq.c:85
misc drawing utilities
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:326
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
int bpp
bytes per pixel
Definition: vf_histeq.c:66
HisteqAntibanding
Definition: vf_histeq.c:50
AVFILTER_DEFINE_CLASS(histeq)
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
#define A
Definition: vf_histeq.c:124
const char * name
Filter name.
Definition: avfilter.h:148
static int query_formats(AVFilterContext *ctx)
Definition: vf_histeq.c:96
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:275
int antibanding
HisteqAntibanding.
Definition: vf_histeq.c:61
#define flags(name, subs,...)
Definition: cbs_av1.c:561
static const AVFilterPad histeq_inputs[]
Definition: vf_histeq.c:255
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
common internal and external API header
#define B
Definition: vf_histeq.c:123
A list of supported formats for one end of a filter link.
Definition: formats.h:64
An instance of a filter.
Definition: avfilter.h:338
#define LCG_M
Definition: vf_histeq.c:46
#define G
Definition: vf_histeq.c:122
internal API functions
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
int LUT[256]
lookup table derived from histogram[]
Definition: vf_histeq.c:64
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
for(j=16;j >0;--j)
int av_frame_copy_props(AVFrame *dst, const AVFrame *src)
Copy only "metadata" fields from src to dst.
Definition: frame.c:654
#define FFMAX3(a, b, c)
Definition: common.h:95
float strength
Definition: vf_histeq.c:59