vf_histeq.c File Reference

Histogram equalization filter, based on the VirtualDub filter by Donald A. More...

#include "libavutil/common.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "avfilter.h"
#include "drawutils.h"
#include "formats.h"
#include "internal.h"
#include "video.h"

Go to the source code of this file.

Data Structures
struct	HisteqContext

Macros
#define	LCG_A   4096
#define	LCG_C   150889
#define	LCG_M   714025
#define	LCG(x)   (((x) * LCG_A + LCG_C) % LCG_M)
#define	LCG_SEED   739187
#define	OFFSET(x)   offsetof(HisteqContext, x)
#define	FLAGS   AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
#define	CONST(name, help, val, unit)   { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }
#define	R   0
#define	G   1
#define	B   2
#define	A   3
#define	GET_RGB_VALUES(r, g, b, src, map)

Enumerations
enum	HisteqAntibanding { HISTEQ_ANTIBANDING_NONE = 0, HISTEQ_ANTIBANDING_WEAK = 1, HISTEQ_ANTIBANDING_STRONG = 2, HISTEQ_ANTIBANDING_NB }

Functions
	AVFILTER_DEFINE_CLASS (histeq)
static av_cold int	init (AVFilterContext *ctx, const char *args)
static av_cold void	uninit (AVFilterContext *ctx)
static int	query_formats (AVFilterContext *ctx)
static int	config_input (AVFilterLink *inlink)
static int	filter_frame (AVFilterLink *inlink, AVFilterBufferRef *inpic)

Variables
static const AVOption	histeq_options []
static const AVFilterPad	histeq_inputs []
static const AVFilterPad	histeq_outputs []
AVFilter	avfilter_vf_histeq

Detailed Description

Histogram equalization filter, based on the VirtualDub filter by Donald A.

Graft <neuron2 at="" home="" dot="" com>="">. Implements global automatic contrast adjustment by means of histogram equalization.

Definition in file vf_histeq.c.

Macro Definition Documentation

#define LCG_A   4096

Definition at line 43 of file vf_histeq.c.

#define LCG_C   150889

Definition at line 44 of file vf_histeq.c.

#define LCG_M   714025

Definition at line 45 of file vf_histeq.c.

Referenced by filter_frame().

#define LCG

(

x

)

(((x) * LCG_A + LCG_C) % LCG_M)

Definition at line 46 of file vf_histeq.c.

Referenced by filter_frame().

#define LCG_SEED   739187

Definition at line 47 of file vf_histeq.c.

Referenced by filter_frame().

#define OFFSET

(

x

)

offsetof(HisteqContext, x)

Definition at line 69 of file vf_histeq.c.

#define FLAGS   AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

Definition at line 70 of file vf_histeq.c.

#define CONST	(		name,
			help,
			val,
			unit
	)		{ name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }

Definition at line 71 of file vf_histeq.c.

#define R   0

Definition at line 134 of file vf_histeq.c.

Referenced by filter_frame().

#define G   1

Definition at line 135 of file vf_histeq.c.

Referenced by filter_frame().

#define B   2

Definition at line 136 of file vf_histeq.c.

Referenced by filter_frame().

#define A   3

Definition at line 137 of file vf_histeq.c.

#define GET_RGB_VALUES	(		r,
			g,
			b,
			src,
			map
	)

Value:

do { \
    r = src[x + map[R]];                       \
    g = src[x + map[G]];                       \
    b = src[x + map[B]];                       \
} while (0)

Definition at line 139 of file vf_histeq.c.

Referenced by filter_frame().

Enumeration Type Documentation

enum HisteqAntibanding

Enumerator:

HISTEQ_ANTIBANDING_NONE
HISTEQ_ANTIBANDING_WEAK
HISTEQ_ANTIBANDING_STRONG
HISTEQ_ANTIBANDING_NB

Definition at line 49 of file vf_histeq.c.

Function Documentation

AVFILTER_DEFINE_CLASS

(

histeq

)

static av_cold int init ( AVFilterContext *  ctx, const char *  args  )

static

Definition at line 85 of file vf_histeq.c.

static av_cold void uninit ( AVFilterContext *  ctx )

static

Definition at line 104 of file vf_histeq.c.

static int query_formats ( AVFilterContext *  ctx )

static

Definition at line 110 of file vf_histeq.c.

static int config_input ( AVFilterLink *  inlink )

static

Definition at line 122 of file vf_histeq.c.

static int filter_frame ( AVFilterLink *  inlink, AVFilterBufferRef *  inpic  )

static

Definition at line 145 of file vf_histeq.c.

Variable Documentation

const AVOption histeq_options[]

static

Initial value:

= {
    { "strength",    "set the strength", OFFSET(strength), AV_OPT_TYPE_FLOAT, {.dbl=0.2}, 0, 1, FLAGS },
    { "intensity",   "set the intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.21}, 0, 1, FLAGS },
    { "antibanding", "set the antibanding level", OFFSET(antibanding), AV_OPT_TYPE_INT, {.i64=HISTEQ_ANTIBANDING_NONE}, 0, HISTEQ_ANTIBANDING_NB-1, FLAGS, "antibanding" },
    CONST("none",    "apply no antibanding",     HISTEQ_ANTIBANDING_NONE,   "antibanding"),
    CONST("weak",    "apply weak antibanding",   HISTEQ_ANTIBANDING_WEAK,   "antibanding"),
    CONST("strong",  "apply strong antibanding", HISTEQ_ANTIBANDING_STRONG, "antibanding"),
    { NULL }
}

Definition at line 73 of file vf_histeq.c.

const AVFilterPad histeq_inputs[]

static

Initial value:

= {
    {
        .name             = "default",
        .type             = AVMEDIA_TYPE_VIDEO,
        .config_props     = config_input,
        .filter_frame     = filter_frame,
        .min_perms        = AV_PERM_READ,
    },
    { NULL }
}

Definition at line 268 of file vf_histeq.c.

const AVFilterPad histeq_outputs[]

static

Initial value:

= {
    {
        .name             = "default",
        .type             = AVMEDIA_TYPE_VIDEO,
    },
    { NULL }
}

Definition at line 279 of file vf_histeq.c.

AVFilter avfilter_vf_histeq

Initial value:

= {
    .name          = "histeq",
    .description   = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."),
    .priv_size     = sizeof(HisteqContext),
    .init          = init,
    .uninit        = uninit,
    .query_formats = query_formats,

    .inputs        = histeq_inputs,
    .outputs       = histeq_outputs,
    .priv_class    = &histeq_class,
}

Definition at line 287 of file vf_histeq.c.