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  };
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) {
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 
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,
281  .priv_class = &histeq_class,
283 };
HISTEQ_ANTIBANDING_WEAK
@ HISTEQ_ANTIBANDING_WEAK
Definition: vf_histeq.c:52
ff_get_video_buffer
AVFrame * ff_get_video_buffer(AVFilterLink *link, int w, int h)
Request a picture buffer with a specific set of permissions.
Definition: video.c:97
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
r
const char * r
Definition: vf_curves.c:116
AVERROR
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
opt.h
ff_make_format_list
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:286
histeq_options
static const AVOption histeq_options[]
Definition: vf_histeq.c:73
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:978
av_pix_fmt_desc_get
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2540
inlink
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
Definition: filter_design.txt:212
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:112
ff_vf_histeq
const AVFilter ff_vf_histeq
Definition: vf_histeq.c:273
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
pixdesc.h
B
#define B
Definition: vf_histeq.c:123
AVOption
AVOption.
Definition: opt.h:247
b
#define b
Definition: input.c:40
AV_LOG_VERBOSE
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:196
AV_PIX_FMT_BGR24
@ AV_PIX_FMT_BGR24
packed RGB 8:8:8, 24bpp, BGRBGR...
Definition: pixfmt.h:69
AV_PIX_FMT_BGRA
@ AV_PIX_FMT_BGRA
packed BGRA 8:8:8:8, 32bpp, BGRABGRA...
Definition: pixfmt.h:95
av_get_bits_per_pixel
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:2492
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:149
video.h
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:317
HisteqContext::bpp
int bpp
bytes per pixel
Definition: vf_histeq.c:66
AVFilterFormats
A list of supported formats for one end of a filter link.
Definition: formats.h:64
formats.h
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:54
histeq_outputs
static const AVFilterPad histeq_outputs[]
Definition: vf_histeq.c:265
GET_RGB_VALUES
#define GET_RGB_VALUES(r, g, b, src, map)
Definition: vf_histeq.c:126
av_cold
#define av_cold
Definition: attributes.h:90
inputs
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
Definition: filter_design.txt:243
ff_set_common_formats
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:580
FFMAX3
#define FFMAX3(a, b, c)
Definition: common.h:104
g
const char * g
Definition: vf_curves.c:117
outputs
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
pix_fmts
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:290
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AV_PIX_FMT_RGBA
@ AV_PIX_FMT_RGBA
packed RGBA 8:8:8:8, 32bpp, RGBARGBA...
Definition: pixfmt.h:93
LCG
#define LCG(x)
Definition: vf_histeq.c:47
HisteqContext::strength
float strength
Definition: vf_histeq.c:59
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
av_frame_copy_props
int av_frame_copy_props(AVFrame *dst, const AVFrame *src)
Copy only "metadata" fields from src to dst.
Definition: frame.c:537
inpic
av_frame_free & inpic
Definition: vf_mcdeint.c:281
init
static av_cold int init(AVFilterContext *ctx)
Definition: vf_histeq.c:85
src
#define src
Definition: vp8dsp.c:255
AV_PIX_FMT_ABGR
@ AV_PIX_FMT_ABGR
packed ABGR 8:8:8:8, 32bpp, ABGRABGR...
Definition: pixfmt.h:94
HISTEQ_ANTIBANDING_NONE
@ HISTEQ_ANTIBANDING_NONE
Definition: vf_histeq.c:51
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
CONST
#define CONST(name, help, val, unit)
Definition: vf_histeq.c:71
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:29
AV_PIX_FMT_RGB24
@ AV_PIX_FMT_RGB24
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:68
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:116
HisteqContext::in_histogram
int in_histogram[256]
input histogram
Definition: vf_histeq.c:62
A
#define A
Definition: vf_histeq.c:124
HisteqContext::rgba_map
uint8_t rgba_map[4]
components position
Definition: vf_histeq.c:65
histeq_inputs
static const AVFilterPad histeq_inputs[]
Definition: vf_histeq.c:255
query_formats
static int query_formats(AVFilterContext *ctx)
Definition: vf_histeq.c:96
HisteqContext
Definition: vf_histeq.c:57
HisteqContext::antibanding
int antibanding
HisteqAntibanding.
Definition: vf_histeq.c:61
internal.h
AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
#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:126
AV_PIX_FMT_ARGB
@ AV_PIX_FMT_ARGB
packed ARGB 8:8:8:8, 32bpp, ARGBARGB...
Definition: pixfmt.h:92
AV_OPT_TYPE_FLOAT
@ AV_OPT_TYPE_FLOAT
Definition: opt.h:227
R
#define R
Definition: vf_histeq.c:121
i
int i
Definition: input.c:406
internal.h
common.h
config_input
static int config_input(AVFilterLink *inlink)
Definition: vf_histeq.c:109
HisteqContext::out_histogram
int out_histogram[256]
output histogram
Definition: vf_histeq.c:63
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:60
AVFilter
Filter definition.
Definition: avfilter.h:145
HisteqContext::LUT
int LUT[256]
lookup table derived from histogram[]
Definition: vf_histeq.c:64
OFFSET
#define OFFSET(x)
Definition: vf_histeq.c:69
LCG_M
#define LCG_M
Definition: vf_histeq.c:46
G
#define G
Definition: vf_histeq.c:122
HisteqAntibanding
HisteqAntibanding
Definition: vf_histeq.c:50
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:65
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:224
avfilter.h
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(histeq)
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *inpic)
Definition: vf_histeq.c:132
av_clip_uint8
#define av_clip_uint8
Definition: common.h:128
AVFilterContext
An instance of a filter.
Definition: avfilter.h:333
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVPixFmtDescriptor
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:69
FLAGS
#define FLAGS
Definition: vf_histeq.c:70
ff_fill_rgba_map
int ff_fill_rgba_map(uint8_t *rgba_map, enum AVPixelFormat pix_fmt)
Definition: drawutils.c:33
HISTEQ_ANTIBANDING_STRONG
@ HISTEQ_ANTIBANDING_STRONG
Definition: vf_histeq.c:53
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:334
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
drawutils.h
LCG_SEED
#define LCG_SEED
Definition: vf_histeq.c:48
HISTEQ_ANTIBANDING_NB
@ HISTEQ_ANTIBANDING_NB
Definition: vf_histeq.c:54
HisteqContext::intensity
float intensity
Definition: vf_histeq.c:60