vf_grayworld.c File Reference

#include "libavutil/imgutils.h"
#include "libavutil/mem.h"
#include "avfilter.h"
#include "internal.h"
#include "video.h"

Go to the source code of this file.

Data Structures
struct	ThreadData
	Used for passing data between threads. More...
struct	GrayWorldContext

Functions
static void	apply_matrix (const float matrix[3][3], const float input[3], float output[3])
static void	rgb2lab (const float rgb[3], float lab[3])
	Convert from Linear RGB to logspace LAB. More...
static void	lab2rgb (const float lab[3], float rgb[3])
	Convert from Logspace LAB to Linear RGB. More...
static int	convert_frame (AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
	Convert a frame from linear RGB to logspace LAB, and accumulate channel totals for each row Convert from RGB -> lms using equation 4 in color transfer paper. More...
static void	compute_correction (GrayWorldContext *s, ThreadData *td)
	Sum the channel totals and compute the mean for each channel. More...
static int	correct_frame (AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
	Subtract the mean logspace AB values from each pixel. More...
static int	config_input (AVFilterLink *inlink)
static av_cold void	uninit (AVFilterContext *ctx)
static int	filter_frame (AVFilterLink *inlink, AVFrame *in)

Variables
static const float	lms2lab [3][3]
static const float	lab2lms [3][3]
static const float	rgb2lms [3][3]
static const float	lms2rgb [3][3]
static const AVFilterPad	grayworld_inputs []
const AVFilter	ff_vf_grayworld

Detailed Description

Color correction filter based on https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging

Definition in file vf_grayworld.c.

Function Documentation

apply_matrix()

static void apply_matrix ( const float  matrix[3][3], const float  input[3], float  output[3]  )

static

Definition at line 48 of file vf_grayworld.c.

Referenced by lab2rgb(), and rgb2lab().

rgb2lab()

static void rgb2lab ( const float  rgb[3], float  lab[3]  )

static

Convert from Linear RGB to logspace LAB.

Parameters

rgb	Input array of rgb components
lab	output array of lab components

Definition at line 85 of file vf_grayworld.c.

Referenced by convert_frame().

lab2rgb()

static void lab2rgb ( const float  lab[3], float  rgb[3]  )

static

Convert from Logspace LAB to Linear RGB.

Parameters

lab	input array of lab components
rgb	output array of rgb components

Definition at line 102 of file vf_grayworld.c.

Referenced by correct_frame().

convert_frame()

static int convert_frame ( AVFilterContext *  ctx, void *  arg, int  jobnr, int  nb_jobs  )

static

Convert a frame from linear RGB to logspace LAB, and accumulate channel totals for each row Convert from RGB -> lms using equation 4 in color transfer paper.

Parameters

ctx	Filter context
arg	Thread data pointer
jobnr	job number
nb_jobs	number of jobs

Definition at line 122 of file vf_grayworld.c.

Referenced by filter_frame().

compute_correction()

static void compute_correction ( GrayWorldContext *  s, ThreadData *  td  )

static

Sum the channel totals and compute the mean for each channel.

Parameters

s	Frame context
td	thread data

Definition at line 167 of file vf_grayworld.c.

Referenced by filter_frame().

correct_frame()

static int correct_frame ( AVFilterContext *  ctx, void *  arg, int  jobnr, int  nb_jobs  )

static

Subtract the mean logspace AB values from each pixel.

Parameters

ctx	Filter context
arg	Thread data pointer
jobnr	job number
nb_jobs	number of jobs

Definition at line 190 of file vf_grayworld.c.

Referenced by filter_frame().

config_input()

static int config_input ( AVFilterLink *  inlink )

static

Definition at line 227 of file vf_grayworld.c.

uninit()

static av_cold void uninit ( AVFilterContext *  ctx )

static

Definition at line 240 of file vf_grayworld.c.

filter_frame()

static int filter_frame ( AVFilterLink *  inlink, AVFrame *  in  )

static

Definition at line 249 of file vf_grayworld.c.

Variable Documentation

lms2lab

const float lms2lab[3][3]

static

Initial value:

= {
    {0.5774, 0.5774, 0.5774},
    {0.40825, 0.40825, -0.816458},
    {0.707, -0.707, 0}
}

Definition at line 55 of file vf_grayworld.c.

Referenced by rgb2lab().

lab2lms

const float lab2lms[3][3]

static

Initial value:

= {
    {0.57735, 0.40825, 0.707},
    {0.57735, 0.40825, -0.707},
    {0.57735, -0.8165, 0}
}

Definition at line 61 of file vf_grayworld.c.

Referenced by lab2rgb().

rgb2lms

const float rgb2lms[3][3]

static

Initial value:

= {
    {0.3811, 0.5783, 0.0402},
    {0.1967, 0.7244, 0.0782},
    {0.0241, 0.1288, 0.8444}
}

Definition at line 67 of file vf_grayworld.c.

Referenced by rgb2lab().

lms2rgb

const float lms2rgb[3][3]

static

Initial value:

= {
    {4.4679, -3.5873, 0.1193},
    {-1.2186, 2.3809, -0.1624},
    {0.0497, -0.2439, 1.2045}
}

Definition at line 73 of file vf_grayworld.c.

Referenced by lab2rgb().

grayworld_inputs

const AVFilterPad grayworld_inputs[]

static

Initial value:

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

Definition at line 291 of file vf_grayworld.c.

ff_vf_grayworld

const AVFilter ff_vf_grayworld

Initial value:

= {
    .name          = "grayworld",
    .description   = NULL_IF_CONFIG_SMALL("Adjust white balance using LAB gray world algorithm"),
    .priv_size     = sizeof(GrayWorldContext),
    FILTER_INPUTS(grayworld_inputs),
    FILTER_OUTPUTS(ff_video_default_filterpad),
    FILTER_PIXFMTS(AV_PIX_FMT_GBRPF32, AV_PIX_FMT_GBRAPF32),
    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
    .uninit        = uninit,
}

Definition at line 300 of file vf_grayworld.c.