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 "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 
54 };
55 
56 typedef struct HisteqContext {
57  const AVClass *class;
58  float strength;
59  float intensity;
60  int antibanding; ///< HisteqAntibanding
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
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 
85 {
86  HisteqContext *histeq = ctx->priv;
87 
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 const enum AVPixelFormat pix_fmts[] = {
99 };
100 
102 {
103  AVFilterContext *ctx = inlink->dst;
104  HisteqContext *histeq = ctx->priv;
105  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
106 
107  histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8;
108  ff_fill_rgba_map(histeq->rgba_map, inlink->format);
109 
110  return 0;
111 }
112 
113 #define R 0
114 #define G 1
115 #define B 2
116 #define A 3
117 
118 #define GET_RGB_VALUES(r, g, b, src, map) do { \
119  r = src[x + map[R]]; \
120  g = src[x + map[G]]; \
121  b = src[x + map[B]]; \
122 } while (0)
123 
125 {
126  AVFilterContext *ctx = inlink->dst;
127  HisteqContext *histeq = ctx->priv;
128  AVFilterLink *outlink = ctx->outputs[0];
129  int strength = histeq->strength * 1000;
130  int intensity = histeq->intensity * 1000;
131  int x, y, i, luthi, lutlo, lut, luma, oluma, m;
132  AVFrame *outpic;
133  unsigned int r, g, b, jran;
134  uint8_t *src, *dst;
135 
136  outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h);
137  if (!outpic) {
139  return AVERROR(ENOMEM);
140  }
141  av_frame_copy_props(outpic, inpic);
142 
143  /* Seed random generator for antibanding. */
144  jran = LCG_SEED;
145 
146  /* Calculate and store the luminance and calculate the global histogram
147  based on the luminance. */
148  memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram));
149  src = inpic->data[0];
150  dst = outpic->data[0];
151  for (y = 0; y < inlink->h; y++) {
152  for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
153  GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
154  luma = (55 * r + 182 * g + 19 * b) >> 8;
155  dst[x + histeq->rgba_map[A]] = luma;
156  histeq->in_histogram[luma]++;
157  }
158  src += inpic->linesize[0];
159  dst += outpic->linesize[0];
160  }
161 
162 #ifdef DEBUG
163  for (x = 0; x < 256; x++)
164  ff_dlog(ctx, "in[%d]: %u\n", x, histeq->in_histogram[x]);
165 #endif
166 
167  /* Calculate the lookup table. */
168  histeq->LUT[0] = histeq->in_histogram[0];
169  /* Accumulate */
170  for (x = 1; x < 256; x++)
171  histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x];
172 
173  /* Normalize */
174  for (x = 0; x < 256; x++)
175  histeq->LUT[x] = (histeq->LUT[x] * intensity) / (inlink->h * inlink->w);
176 
177  /* Adjust the LUT based on the selected strength. This is an alpha
178  mix of the calculated LUT and a linear LUT with gain 1. */
179  for (x = 0; x < 256; x++)
180  histeq->LUT[x] = (strength * histeq->LUT[x]) / 255 +
181  ((255 - strength) * x) / 255;
182 
183  /* Output the equalized frame. */
184  memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram));
185 
186  src = inpic->data[0];
187  dst = outpic->data[0];
188  for (y = 0; y < inlink->h; y++) {
189  for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
190  luma = dst[x + histeq->rgba_map[A]];
191  if (luma == 0) {
192  for (i = 0; i < histeq->bpp; ++i)
193  dst[x + i] = 0;
194  histeq->out_histogram[0]++;
195  } else {
196  lut = histeq->LUT[luma];
197  if (histeq->antibanding != HISTEQ_ANTIBANDING_NONE) {
198  if (luma > 0) {
199  lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ?
200  (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 :
201  histeq->LUT[luma - 1];
202  } else
203  lutlo = lut;
204 
205  if (luma < 255) {
206  luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ?
207  (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 :
208  histeq->LUT[luma + 1];
209  } else
210  luthi = lut;
211 
212  if (lutlo != luthi) {
213  jran = LCG(jran);
214  lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M;
215  }
216  }
217 
218  GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
219  if (((m = FFMAX3(r, g, b)) * lut) / luma > 255) {
220  r = (r * 255) / m;
221  g = (g * 255) / m;
222  b = (b * 255) / m;
223  } else {
224  r = (r * lut) / luma;
225  g = (g * lut) / luma;
226  b = (b * lut) / luma;
227  }
228  dst[x + histeq->rgba_map[R]] = r;
229  dst[x + histeq->rgba_map[G]] = g;
230  dst[x + histeq->rgba_map[B]] = b;
231  oluma = av_clip_uint8((55 * r + 182 * g + 19 * b) >> 8);
232  histeq->out_histogram[oluma]++;
233  }
234  }
235  src += inpic->linesize[0];
236  dst += outpic->linesize[0];
237  }
238 #ifdef DEBUG
239  for (x = 0; x < 256; x++)
240  ff_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]);
241 #endif
242 
244  return ff_filter_frame(outlink, outpic);
245 }
246 
247 static const AVFilterPad histeq_inputs[] = {
248  {
249  .name = "default",
250  .type = AVMEDIA_TYPE_VIDEO,
251  .config_props = config_input,
252  .filter_frame = filter_frame,
253  },
254 };
255 
257  .name = "histeq",
258  .description = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."),
259  .priv_size = sizeof(HisteqContext),
260  .init = init,
264  .priv_class = &histeq_class,
266 };
HISTEQ_ANTIBANDING_WEAK
@ HISTEQ_ANTIBANDING_WEAK
Definition: vf_histeq.c:51
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:108
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
r
const char * r
Definition: vf_curves.c:126
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
histeq_options
static const AVOption histeq_options[]
Definition: vf_histeq.c:72
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:2936
FILTER_PIXFMTS_ARRAY
#define FILTER_PIXFMTS_ARRAY(array)
Definition: internal.h:172
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:100
ff_vf_histeq
const AVFilter ff_vf_histeq
Definition: vf_histeq.c:256
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
pixdesc.h
B
#define B
Definition: vf_histeq.c:115
AVOption
AVOption.
Definition: opt.h:251
b
#define b
Definition: input.c:41
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:2888
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:170
video.h
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:361
HisteqContext::bpp
int bpp
bytes per pixel
Definition: vf_histeq.c:65
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:47
GET_RGB_VALUES
#define GET_RGB_VALUES(r, g, b, src, map)
Definition: vf_histeq.c:118
av_cold
#define av_cold
Definition: attributes.h:90
pix_fmts
static enum AVPixelFormat pix_fmts[]
Definition: vf_histeq.c:95
ff_video_default_filterpad
const AVFilterPad ff_video_default_filterpad[1]
An AVFilterPad array whose only entry has name "default" and is of type AVMEDIA_TYPE_VIDEO.
Definition: video.c:36
g
const char * g
Definition: vf_curves.c:127
ctx
AVFormatContext * ctx
Definition: movenc.c:48
FILTER_INPUTS
#define FILTER_INPUTS(array)
Definition: internal.h:192
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:46
HisteqContext::strength
float strength
Definition: vf_histeq.c:58
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:736
inpic
av_frame_free & inpic
Definition: vf_mcdeint.c:285
init
static av_cold int init(AVFilterContext *ctx)
Definition: vf_histeq.c:84
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:50
CONST
#define CONST(name, help, val, unit)
Definition: vf_histeq.c:70
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:28
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:106
LUT
Definition: vf_morpho.c:62
HisteqContext::in_histogram
int in_histogram[256]
input histogram
Definition: vf_histeq.c:61
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
A
#define A
Definition: vf_histeq.c:116
HisteqContext::rgba_map
uint8_t rgba_map[4]
components position
Definition: vf_histeq.c:64
histeq_inputs
static const AVFilterPad histeq_inputs[]
Definition: vf_histeq.c:247
HisteqContext
Definition: vf_histeq.c:56
HisteqContext::antibanding
int antibanding
HisteqAntibanding.
Definition: vf_histeq.c:60
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:147
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:228
R
#define R
Definition: vf_histeq.c:113
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:244
internal.h
common.h
config_input
static int config_input(AVFilterLink *inlink)
Definition: vf_histeq.c:101
HisteqContext::out_histogram
int out_histogram[256]
output histogram
Definition: vf_histeq.c:62
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:53
AVFilter
Filter definition.
Definition: avfilter.h:166
HisteqContext::LUT
int LUT[256]
lookup table derived from histogram[]
Definition: vf_histeq.c:63
OFFSET
#define OFFSET(x)
Definition: vf_histeq.c:68
LCG_M
#define LCG_M
Definition: vf_histeq.c:45
G
#define G
Definition: vf_histeq.c:114
HisteqAntibanding
HisteqAntibanding
Definition: vf_histeq.c:49
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:65
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:225
avfilter.h
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(histeq)
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *inpic)
Definition: vf_histeq.c:124
av_clip_uint8
#define av_clip_uint8
Definition: common.h:102
AVFilterContext
An instance of a filter.
Definition: avfilter.h:397
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:69
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:193
src
INIT_CLIP pixel * src
Definition: h264pred_template.c:418
ff_fill_rgba_map
int ff_fill_rgba_map(uint8_t *rgba_map, enum AVPixelFormat pix_fmt)
Definition: drawutils.c:35
FFMAX3
#define FFMAX3(a, b, c)
Definition: macros.h:48
HISTEQ_ANTIBANDING_STRONG
@ HISTEQ_ANTIBANDING_STRONG
Definition: vf_histeq.c:52
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, a positive or negative value, which is typically indicating the size in bytes of each pict...
Definition: frame.h:385
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
drawutils.h
LCG_SEED
#define LCG_SEED
Definition: vf_histeq.c:47
HISTEQ_ANTIBANDING_NB
@ HISTEQ_ANTIBANDING_NB
Definition: vf_histeq.c:53
HisteqContext::intensity
float intensity
Definition: vf_histeq.c:59