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avfilter: Add colorconstancy filter 

Signed-off-by: Mina <minasamy_@hotmail.com>
tags/n4.1
Mina Thilo Borgmann 7 years ago
parent
d134b8d85f
commit
0bb5cd8c4d
6 changed files with 803 additions and 0 deletions
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  1. +1
    -0
      Changelog
  2. +1
    -0
      MAINTAINERS
  3. +41
    -0
      doc/filters.texi
  4. +1
    -0
      libavfilter/Makefile
  5. +1
    -0
      libavfilter/allfilters.c
  6. +758
    -0
      libavfilter/vf_colorconstancy.c

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Changelog View File

@@ -15,6 +15,7 @@ version <next>:
- vc1 decoder is now bit-exact - vc1 decoder is now bit-exact
- ATRAC9 decoder - ATRAC9 decoder
- lensfun wrapper filter - lensfun wrapper filter
- colorconstancy filter




version 4.0: version 4.0:


+ 1
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MAINTAINERS View File

@@ -332,6 +332,7 @@ Filters:
vf_bwdif Thomas Mundt (CC <thomas.mundt@hr.de>) vf_bwdif Thomas Mundt (CC <thomas.mundt@hr.de>)
vf_chromakey.c Timo Rothenpieler vf_chromakey.c Timo Rothenpieler
vf_colorchannelmixer.c Paul B Mahol vf_colorchannelmixer.c Paul B Mahol
vf_colorconstancy.c Mina Sami (CC <minas.gorgy@gmail.com>)
vf_colorbalance.c Paul B Mahol vf_colorbalance.c Paul B Mahol
vf_colorkey.c Timo Rothenpieler vf_colorkey.c Timo Rothenpieler
vf_colorlevels.c Paul B Mahol vf_colorlevels.c Paul B Mahol


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- 0
doc/filters.texi View File

@@ -9940,6 +9940,47 @@ gradfun=radius=8


@end itemize @end itemize


@section greyedge
A color constancy variation filter which estimates scene illumination via grey edge algorithm
and corrects the scene colors accordingly.

See: @url{https://staff.science.uva.nl/th.gevers/pub/GeversTIP07.pdf}

The filter accepts the following options:

@table @option
@item difford
The order of differentiation to be applied on the scene. Must be chosen in the range
[0,2] and default value is 1.

@item minknorm
The Minkowski parameter to be used for calculating the Minkowski distance. Must
be chosen in the range [0,65535] and default value is 1. Set to 0 for getting
max value instead of calculating Minkowski distance.

@item sigma
The standard deviation of Gaussian blur to be applied on the scene. Must be
chosen in the range [0,1024.0] and default value = 1. Sigma can't be set to 0
if @var{difford} is greater than 0.
@end table

@subsection Examples
@itemize

@item
Grey Edge:
@example
greyedge=difford=1:minknorm=5:sigma=2
@end example

@item
Max Edge:
@example
greyedge=difford=1:minknorm=0:sigma=2
@end example

@end itemize

@anchor{haldclut} @anchor{haldclut}
@section haldclut @section haldclut




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libavfilter/Makefile View File

@@ -228,6 +228,7 @@ OBJS-$(CONFIG_FSPP_FILTER) += vf_fspp.o
OBJS-$(CONFIG_GBLUR_FILTER) += vf_gblur.o OBJS-$(CONFIG_GBLUR_FILTER) += vf_gblur.o
OBJS-$(CONFIG_GEQ_FILTER) += vf_geq.o OBJS-$(CONFIG_GEQ_FILTER) += vf_geq.o
OBJS-$(CONFIG_GRADFUN_FILTER) += vf_gradfun.o OBJS-$(CONFIG_GRADFUN_FILTER) += vf_gradfun.o
OBJS-$(CONFIG_GREYEDGE_FILTER) += vf_colorconstancy.o
OBJS-$(CONFIG_HALDCLUT_FILTER) += vf_lut3d.o framesync.o OBJS-$(CONFIG_HALDCLUT_FILTER) += vf_lut3d.o framesync.o
OBJS-$(CONFIG_HFLIP_FILTER) += vf_hflip.o OBJS-$(CONFIG_HFLIP_FILTER) += vf_hflip.o
OBJS-$(CONFIG_HISTEQ_FILTER) += vf_histeq.o OBJS-$(CONFIG_HISTEQ_FILTER) += vf_histeq.o


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libavfilter/allfilters.c View File

@@ -217,6 +217,7 @@ extern AVFilter ff_vf_fspp;
extern AVFilter ff_vf_gblur; extern AVFilter ff_vf_gblur;
extern AVFilter ff_vf_geq; extern AVFilter ff_vf_geq;
extern AVFilter ff_vf_gradfun; extern AVFilter ff_vf_gradfun;
extern AVFilter ff_vf_greyedge;
extern AVFilter ff_vf_haldclut; extern AVFilter ff_vf_haldclut;
extern AVFilter ff_vf_hflip; extern AVFilter ff_vf_hflip;
extern AVFilter ff_vf_histeq; extern AVFilter ff_vf_histeq;


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libavfilter/vf_colorconstancy.c View File

@@ -0,0 +1,758 @@
/*
* Copyright (c) 2018 Mina Sami
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

/**
* @file
* Color Constancy filter
*
* @see http://colorconstancy.com/
*
* @cite
* J. van de Weijer, Th. Gevers, A. Gijsenij "Edge-Based Color Constancy".
*/

#include "libavutil/bprint.h"
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"

#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"

#include <math.h>

#define GREY_EDGE "greyedge"

#define NUM_PLANES 3
#define MAX_DIFF_ORD 2
#define MAX_META_DATA 4
#define MAX_DATA 4

#define INDEX_TEMP 0
#define INDEX_DX 1
#define INDEX_DY 2
#define INDEX_DXY 3
#define INDEX_NORM INDEX_DX
#define INDEX_SRC 0
#define INDEX_DST 1
#define INDEX_ORD 2
#define INDEX_DIR 3
#define DIR_X 0
#define DIR_Y 1

/**
* Used for passing data between threads.
*/
typedef struct ThreadData {
AVFrame *in, *out;
int meta_data[MAX_META_DATA];
double *data[MAX_DATA][NUM_PLANES];
} ThreadData;

/**
* Common struct for all algorithms contexts.
*/
typedef struct ColorConstancyContext {
const AVClass *class;

int difford;
int minknorm; /**< @minknorm = 0 : getMax instead */
double sigma;

int nb_threads;
int planeheight[4];
int planewidth[4];

int filtersize;
double *gauss[MAX_DIFF_ORD+1];

double white[NUM_PLANES];
} ColorConstancyContext;

#define OFFSET(x) offsetof(ColorConstancyContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

#define GINDX(s, i) ( (i) - ((s) >> 2) )

/**
* Sets gauss filters used for calculating gauss derivatives. Filter size
* depends on sigma which is a user option hence we calculate these
* filters each time. Also each higher order depends on lower ones. Sigma
* can be zero only at difford = 0, then we only convert data to double
* instead.
*
* @param ctx the filter context.
*
* @return 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure.
*/
static int set_gauss(AVFilterContext *ctx)
{
ColorConstancyContext *s = ctx->priv;
int filtersize = s->filtersize;
int difford = s->difford;
double sigma = s->sigma;
double sum1, sum2;
int i;

for (i = 0; i <= difford; ++i) {
s->gauss[i] = av_mallocz_array(filtersize, sizeof(*s->gauss[i]));
if (!s->gauss[i]) {
for (; i >= 0; --i) {
av_freep(&s->gauss[i]);
}
av_log(ctx, AV_LOG_ERROR, "Out of memory while allocating gauss buffers.\n");
return AVERROR(ENOMEM);
}
}

// Order 0
av_log(ctx, AV_LOG_TRACE, "Setting 0-d gauss with filtersize = %d.\n", filtersize);
sum1 = 0.0;
if (!sigma) {
s->gauss[0][0] = 1; // Copying data to double instead of convolution
} else {
for (i = 0; i < filtersize; ++i) {
s->gauss[0][i] = exp(- pow(GINDX(filtersize, i), 2.) / (2 * sigma * sigma)) / ( sqrt(2 * M_PI) * sigma );
sum1 += s->gauss[0][i];
}
for (i = 0; i < filtersize; ++i) {
s->gauss[0][i] /= sum1;
}
}
// Order 1
if (difford > 0) {
av_log(ctx, AV_LOG_TRACE, "Setting 1-d gauss with filtersize = %d.\n", filtersize);
sum1 = 0.0;
for (i = 0; i < filtersize; ++i) {
s->gauss[1][i] = - (GINDX(filtersize, i) / pow(sigma, 2)) * s->gauss[0][i];
sum1 += s->gauss[1][i] *GINDX(filtersize, i);
}

for (i = 0; i < filtersize; ++i) {
s->gauss[1][i] /= sum1;
}

// Order 2
if (difford > 1) {
av_log(ctx, AV_LOG_TRACE, "Setting 2-d gauss with filtersize = %d.\n", filtersize);
sum1 = 0.0;
for (i = 0; i < filtersize; ++i) {
s->gauss[2][i] = ( pow(GINDX(filtersize, i), 2) / pow(sigma, 4) - 1/pow(sigma, 2) )
* s->gauss[0][i];
sum1 += s->gauss[2][i];
}

sum2 = 0.0;
for (i = 0; i < filtersize; ++i) {
s->gauss[2][i] -= sum1 / (filtersize);
sum2 += (0.5 * GINDX(filtersize, i) * GINDX(filtersize, i) * s->gauss[2][i]);
}
for (i = 0; i < filtersize ; ++i) {
s->gauss[2][i] /= sum2;
}
}
}
return 0;
}

/**
* Frees up buffers used by grey edge for storing derivatives final
* and intermidiate results. Number of buffers and number of planes
* for last buffer are given so it can be safely called at allocation
* failure instances.
*
* @param td holds the buffers.
* @param nb_buff number of buffers to be freed.
* @param nb_planes number of planes for last buffer to be freed.
*/
static void cleanup_derivative_buffers(ThreadData *td, int nb_buff, int nb_planes)
{
int b, p;

for (b = 0; b < nb_buff; ++b) {
for (p = 0; p < NUM_PLANES; ++p) {
av_freep(&td->data[b][p]);
}
}
// Final buffer may not be fully allocated at fail cases
for (p = 0; p < nb_planes; ++p) {
av_freep(&td->data[b][p]);
}
}

/**
* Allocates buffers used by grey edge for storing derivatives final
* and intermidiate results.
*
* @param ctx the filter context.
* @param td holds the buffers.
*
* @return 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure.
*/
static int setup_derivative_buffers(AVFilterContext* ctx, ThreadData *td)
{
ColorConstancyContext *s = ctx->priv;
int nb_buff = s->difford + 1;
int b, p;

av_log(ctx, AV_LOG_TRACE, "Allocating %d buffer(s) for grey edge.\n", nb_buff);
for (b = 0; b <= nb_buff; ++b) { // We need difford + 1 buffers
for (p = 0; p < NUM_PLANES; ++p) {
td->data[b][p] = av_mallocz_array(s->planeheight[p] * s->planewidth[p], sizeof(*td->data[b][p]));
if (!td->data[b][p]) {
cleanup_derivative_buffers(td, b + 1, p);
av_log(ctx, AV_LOG_ERROR, "Out of memory while allocating derivatives buffers.\n");
return AVERROR(ENOMEM);
}
}
}
return 0;
}

#define CLAMP(x, mx) av_clip((x), 0, (mx-1))
#define INDX2D(r, c, w) ( (r) * (w) + (c) )
#define GAUSS(s, sr, sc, sls, sh, sw, g) ( (s)[ INDX2D(CLAMP((sr), (sh)), CLAMP((sc), (sw)), (sls)) ] * (g) )

/**
* Slice calculation of gaussian derivatives. Applies 1-D gaussian derivative filter
* either horizontally or vertically according to meta data given in thread data.
* When convoluting horizontally source is always the in frame withing thread data
* while when convoluting vertically source is a buffer.
*
* @param ctx the filter context.
* @param arg data to be passed between threads.
* @param jobnr current job nubmer.
* @param nb_jobs total number of jobs.
*
* @return 0.
*/
static int slice_get_derivative(AVFilterContext* ctx, void* arg, int jobnr, int nb_jobs)
{
ColorConstancyContext *s = ctx->priv;
ThreadData *td = arg;
AVFrame *in = td->in;
const int ord = td->meta_data[INDEX_ORD];
const int dir = td->meta_data[INDEX_DIR];
const int src_index = td->meta_data[INDEX_SRC];
const int dst_index = td->meta_data[INDEX_DST];
const int filtersize = s->filtersize;
const double *gauss = s->gauss[ord];
int plane;

for (plane = 0; plane < NUM_PLANES; ++plane) {
const int height = s->planeheight[plane];
const int width = s->planewidth[plane];
const int in_linesize = in->linesize[plane];
double *dst = td->data[dst_index][plane];
int slice_start, slice_end;
int r, c, g;

if (dir == DIR_X) {
/** Applying gauss horizontally along each row */
const uint8_t *src = in->data[plane];
slice_start = (height * jobnr ) / nb_jobs;
slice_end = (height * (jobnr + 1)) / nb_jobs;

for (r = slice_start; r < slice_end; ++r) {
for (c = 0; c < width; ++c) {
dst[INDX2D(r, c, width)] = 0;
for (g = 0; g < filtersize; ++g) {
dst[INDX2D(r, c, width)] += GAUSS(src, r, c + GINDX(filtersize, g),
in_linesize, height, width, gauss[GINDX(filtersize, g)]);
}
}
}
} else {
/** Applying gauss vertically along each column */
const double *src = td->data[src_index][plane];
slice_start = (width * jobnr ) / nb_jobs;
slice_end = (width * (jobnr + 1)) / nb_jobs;

for (c = slice_start; c < slice_end; ++c) {
for (r = 0; r < height; ++r) {
dst[INDX2D(r, c, width)] = 0;
for (g = 0; g < filtersize; ++g) {
dst[INDX2D(r, c, width)] += GAUSS(src, r + GINDX(filtersize, g), c,
width, height, width, gauss[GINDX(filtersize, g)]);
}
}
}
}

}
return 0;
}

/**
* Slice Frobius normalization of gaussian derivatives. Only called for difford values of
* 1 or 2.
*
* @param ctx the filter context.
* @param arg data to be passed between threads.
* @param jobnr current job nubmer.
* @param nb_jobs total number of jobs.
*
* @return 0.
*/
static int slice_normalize(AVFilterContext* ctx, void* arg, int jobnr, int nb_jobs)
{
ColorConstancyContext *s = ctx->priv;
ThreadData *td = arg;
const int difford = s->difford;
int plane;

for (plane = 0; plane < NUM_PLANES; ++plane) {
const int height = s->planeheight[plane];
const int width = s->planewidth[plane];
const int64_t numpixels = width * (int64_t)height;
const int slice_start = (numpixels * jobnr ) / nb_jobs;
const int slice_end = (numpixels * (jobnr+1)) / nb_jobs;
const double *dx = td->data[INDEX_DX][plane];
const double *dy = td->data[INDEX_DY][plane];
double *norm = td->data[INDEX_NORM][plane];
int i;

if (difford == 1) {
for (i = slice_start; i < slice_end; ++i) {
norm[i] = sqrt( pow(dx[i], 2) + pow(dy[i], 2));
}
} else {
const double *dxy = td->data[INDEX_DXY][plane];
for (i = slice_start; i < slice_end; ++i) {
norm[i] = sqrt( pow(dx[i], 2) + 4 * pow(dxy[i], 2) + pow(dy[i], 2) );
}
}
}

return 0;
}

/**
* Utility function for setting up differentiation data/metadata.
*
* @param ctx the filter context.
* @param td to be used for passing data between threads.
* @param ord ord of differentiation.
* @param dir direction of differentiation.
* @param src index of source used for differentiation.
* @param dst index destination used for saving differentiation result.
* @param dim maximum dimension in current direction.
* @param nb_threads number of threads to use.
*/
static void av_always_inline
get_deriv(AVFilterContext *ctx, ThreadData *td, int ord, int dir,
int src, int dst, int dim, int nb_threads) {
td->meta_data[INDEX_ORD] = ord;
td->meta_data[INDEX_DIR] = dir;
td->meta_data[INDEX_SRC] = src;
td->meta_data[INDEX_DST] = dst;
ctx->internal->execute(ctx, slice_get_derivative, td, NULL, FFMIN(dim, nb_threads));
}

/**
* Main control function for calculating gaussian derivatives.
*
* @param ctx the filter context.
* @param td holds the buffers used for storing results.
*
* @return 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure.
*/
static int get_derivative(AVFilterContext *ctx, ThreadData *td)
{
ColorConstancyContext *s = ctx->priv;
int nb_threads = s->nb_threads;
int height = s->planeheight[1];
int width = s->planewidth[1];

switch(s->difford) {
case 0:
if (!s->sigma) { // Only copy once
get_deriv(ctx, td, 0, DIR_X, 0 , INDEX_NORM, height, nb_threads);
} else {
get_deriv(ctx, td, 0, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 0, DIR_Y, INDEX_TEMP, INDEX_NORM, width , nb_threads);
// save to INDEX_NORM because this will not be normalied and
// end gry edge filter expects result to be found in INDEX_NORM
}
return 0;

case 1:
get_deriv(ctx, td, 1, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 0, DIR_Y, INDEX_TEMP, INDEX_DX, width , nb_threads);

get_deriv(ctx, td, 0, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 1, DIR_Y, INDEX_TEMP, INDEX_DY, width , nb_threads);
return 0;

case 2:
get_deriv(ctx, td, 2, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 0, DIR_Y, INDEX_TEMP, INDEX_DX, width , nb_threads);

get_deriv(ctx, td, 0, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 2, DIR_Y, INDEX_TEMP, INDEX_DY, width , nb_threads);

get_deriv(ctx, td, 1, DIR_X, 0, INDEX_TEMP, height, nb_threads);
get_deriv(ctx, td, 1, DIR_Y, INDEX_TEMP, INDEX_DXY, width , nb_threads);
return 0;

default:
av_log(ctx, AV_LOG_ERROR, "Unsupported difford value: %d.\n", s->difford);
return AVERROR(EINVAL);
}

}

/**
* Slice function for grey edge algorithm that does partial summing/maximizing
* of gaussian derivatives.
*
* @param ctx the filter context.
* @param arg data to be passed between threads.
* @param jobnr current job nubmer.
* @param nb_jobs total number of jobs.
*
* @return 0.
*/
static int filter_slice_grey_edge(AVFilterContext* ctx, void* arg, int jobnr, int nb_jobs)
{
ColorConstancyContext *s = ctx->priv;
ThreadData *td = arg;
AVFrame *in = td->in;
int minknorm = s->minknorm;
const uint8_t thresh = 255;
int plane;

for (plane = 0; plane < NUM_PLANES; ++plane) {
const int height = s->planeheight[plane];
const int width = s->planewidth[plane];
const int in_linesize = in->linesize[plane];
const int slice_start = (height * jobnr) / nb_jobs;
const int slice_end = (height * (jobnr+1)) / nb_jobs;
const uint8_t *img_data = in->data[plane];
const double *src = td->data[INDEX_NORM][plane];
double *dst = td->data[INDEX_DST][plane];
int r, c;

dst[jobnr] = 0;
if (!minknorm) {
for (r = slice_start; r < slice_end; ++r) {
for (c = 0; c < width; ++c) {
dst[jobnr] = FFMAX( dst[jobnr], fabs(src[INDX2D(r, c, width)])
* (img_data[INDX2D(r, c, in_linesize)] < thresh) );
}
}
} else {
for (r = slice_start; r < slice_end; ++r) {
for (c = 0; c < width; ++c) {
dst[jobnr] += ( pow( fabs(src[INDX2D(r, c, width)] / 255.), minknorm)
* (img_data[INDX2D(r, c, in_linesize)] < thresh) );
}
}
}
}
return 0;
}

/**
* Main control function for grey edge algorithm.
*
* @param ctx the filter context.
* @param in frame to perfrom grey edge on.
*
* @return 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure.
*/
static int filter_grey_edge(AVFilterContext *ctx, AVFrame *in)
{
ColorConstancyContext *s = ctx->priv;
ThreadData td;
int minknorm = s->minknorm;
int difford = s->difford;
double *white = s->white;
int nb_jobs = FFMIN3(s->planeheight[1], s->planewidth[1], s->nb_threads);
int plane, job, ret;

td.in = in;
ret = setup_derivative_buffers(ctx, &td);
if (ret) {
return ret;
}
get_derivative(ctx, &td);
if (difford > 0) {
ctx->internal->execute(ctx, slice_normalize, &td, NULL, nb_jobs);
}

ctx->internal->execute(ctx, filter_slice_grey_edge, &td, NULL, nb_jobs);
if (!minknorm) {
for (plane = 0; plane < NUM_PLANES; ++plane) {
white[plane] = 0; // All values are absolute
for (job = 0; job < nb_jobs; ++job) {
white[plane] = FFMAX(white[plane] , td.data[INDEX_DST][plane][job]);
}
}
} else {
for (plane = 0; plane < NUM_PLANES; ++plane) {
white[plane] = 0;
for (job = 0; job < nb_jobs; ++job) {
white[plane] += td.data[INDEX_DST][plane][job];
}
white[plane] = pow(white[plane], 1./minknorm);
}
}

cleanup_derivative_buffers(&td, difford + 1, NUM_PLANES);
return 0;
}

/**
* Normalizes estimated illumination since only illumination vector
* direction is required for color constancy.
*
* @param light the estimated illumination to be normalized in place
*/
static void normalize_light(double *light)
{
double abs_val = pow( pow(light[0], 2.0) + pow(light[1], 2.0) + pow(light[2], 2.0), 0.5);
int plane;

// TODO: check if setting to 1.0 when estimated = 0.0 is the best thing to do

if (!abs_val) {
for (plane = 0; plane < NUM_PLANES; ++plane) {
light[plane] = 1.0;
}
} else {
for (plane = 0; plane < NUM_PLANES; ++plane) {
light[plane] = (light[plane] / abs_val);
if (!light[plane]) { // to avoid division by zero when correcting
light[plane] = 1.0;
}
}
}
}

/**
* Redirects to corresponding algorithm estimation function and performs normalization
* after estimation.
*
* @param ctx the filter context.
* @param in frame to perfrom estimation on.
*
* @return 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure.
*/
static int illumination_estimation(AVFilterContext *ctx, AVFrame *in)
{
ColorConstancyContext *s = ctx->priv;
int ret;

ret = filter_grey_edge(ctx, in);

av_log(ctx, AV_LOG_DEBUG, "Estimated illumination= %f %f %f\n",
s->white[0], s->white[1], s->white[2]);
normalize_light(s->white);
av_log(ctx, AV_LOG_DEBUG, "Estimated illumination after normalization= %f %f %f\n",
s->white[0], s->white[1], s->white[2]);

return ret;
}

/**
* Performs simple correction via diagonal transformation model.
*
* @param ctx the filter context.
* @param arg data to be passed between threads.
* @param jobnr current job nubmer.
* @param nb_jobs total number of jobs.
*
* @return 0.
*/
static int diagonal_transformation(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
{
ColorConstancyContext *s = ctx->priv;
ThreadData *td = arg;
AVFrame *in = td->in;
AVFrame *out = td->out;
double sqrt3 = pow(3.0, 0.5);
int plane;

for (plane = 0; plane < NUM_PLANES; ++plane) {
const int height = s->planeheight[plane];
const int width = s->planewidth[plane];
const int64_t numpixels = width * (int64_t)height;
const int slice_start = (numpixels * jobnr) / nb_jobs;
const int slice_end = (numpixels * (jobnr+1)) / nb_jobs;
const uint8_t *src = in->data[plane];
uint8_t *dst = out->data[plane];
double temp;
unsigned i;

for (i = slice_start; i < slice_end; ++i) {
temp = src[i] / (s->white[plane] * sqrt3);
dst[i] = av_clip_uint8((int)(temp + 0.5));
}
}
return 0;
}

/**
* Main control function for correcting scene illumination based on
* estimated illumination.
*
* @param ctx the filter context.
* @param in holds frame to correct
* @param out holds corrected frame
*/
static void chromatic_adaptation(AVFilterContext *ctx, AVFrame *in, AVFrame *out)
{
ColorConstancyContext *s = ctx->priv;
ThreadData td;
int nb_jobs = FFMIN3(s->planeheight[1], s->planewidth[1], s->nb_threads);

td.in = in;
td.out = out;
ctx->internal->execute(ctx, diagonal_transformation, &td, NULL, nb_jobs);
}

static int query_formats(AVFilterContext *ctx)
{
static const enum AVPixelFormat pix_fmts[] = {
// TODO: support more formats
// FIXME: error when saving to .jpg
AV_PIX_FMT_GBRP,
AV_PIX_FMT_NONE
};

return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
}

static int config_props(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->dst;
ColorConstancyContext *s = ctx->priv;
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
const double break_off_sigma = 3.0;
double sigma = s->sigma;
int ret;

if (!sigma && s->difford) {
av_log(ctx, AV_LOG_ERROR, "Sigma can't be set to 0 when difford > 0.\n");
return AVERROR(EINVAL);
}

s->filtersize = 2 * floor(break_off_sigma * s->sigma + 0.5) + 1;
if (ret=set_gauss(ctx)) {
return ret;
}

s->nb_threads = ff_filter_get_nb_threads(ctx);
s->planewidth[1] = s->planewidth[2] = AV_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
s->planewidth[0] = s->planewidth[3] = inlink->w;
s->planeheight[1] = s->planeheight[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
s->planeheight[0] = s->planeheight[3] = inlink->h;

return 0;
}

static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
AVFrame *out;
int ret;

ret = illumination_estimation(ctx, in);
if (ret) {
return ret;
}

if (av_frame_is_writable(in)) {
out = in;
} else {
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out) {
av_log(ctx, AV_LOG_ERROR, "Out of memory while allocating output video buffer.\n");
return AVERROR(ENOMEM);
}
av_frame_copy_props(out, in);
}
chromatic_adaptation(ctx, in, out);

return ff_filter_frame(outlink, out);
}

static av_cold void uninit(AVFilterContext *ctx)
{
ColorConstancyContext *s = ctx->priv;
int difford = s->difford;
int i;

for (i = 0; i <= difford; ++i) {
av_freep(&s->gauss[i]);
}
}

static const AVFilterPad colorconstancy_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_props,
.filter_frame = filter_frame,
},
{ NULL }
};

static const AVFilterPad colorconstancy_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
},
{ NULL }
};

#if CONFIG_GREYEDGE_FILTER

static const AVOption greyedge_options[] = {
{ "difford", "set differentiation order", OFFSET(difford), AV_OPT_TYPE_INT, {.i64=1}, 0, 2, FLAGS },
{ "minknorm", "set Minkowski norm", OFFSET(minknorm), AV_OPT_TYPE_INT, {.i64=1}, 0, 65535, FLAGS },
{ "sigma", "set sigma", OFFSET(sigma), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0.0, 1024.0, FLAGS },
{ NULL }
};

AVFILTER_DEFINE_CLASS(greyedge);

AVFilter ff_vf_greyedge = {
.name = GREY_EDGE,
.description = NULL_IF_CONFIG_SMALL("Estimates scene illumination by grey edge assumption."),
.priv_size = sizeof(ColorConstancyContext),
.priv_class = &greyedge_class,
.query_formats = query_formats,
.uninit = uninit,
.inputs = colorconstancy_inputs,
.outputs = colorconstancy_outputs,
.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
};

#endif /* CONFIG_GREY_EDGE_FILTER */

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