box_filters.h

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/*
    This file is part of darktable,
    Copyright (C) 2009-2011 johannes hanika.
    Copyright (C) 2012 Richard Wonka.
    Copyright (C) 2016 Roman Lebedev.
    Copyright (C) 2016 Tobias Ellinghaus.
    Copyright (C) 2018 rawfiner.
    Copyright (C) 2020-2021 Pascal Obry.
    Copyright (C) 2020-2021 Ralf Brown.
    Copyright (C) 2022 Martin Bařinka.
    Copyright (C) 2026 Aurélien PIERRE.
    
    darktable is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
    
    darktable 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 General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#pragma once
 
#include <stdlib.h>
 
// default number of iterations to run for dt_box_mean
#define BOX_ITERATIONS 8
 
// flag to add to number of channels to request the slower but more accurate version using Kahan (compensated)
// summation
#define BOXFILTER_KAHAN_SUM 0x1000000
 
// ch = number of channels per pixel.  Supported values: 1, 2, 4, and 4|Kahan
int dt_box_mean(float *const buf, const size_t height, const size_t width, const int ch,
                const int radius, const unsigned interations);
// run a single iteration horizonally over a single row.  Supported values for ch: 4|Kahan
// 'scratch' must point at a buffer large enough to hold ch*width floats, or be NULL
int dt_box_mean_horizontal(float *const restrict buf, const size_t width, const int ch, const int radius,
                           float *const restrict scratch);
// run a single iteration vertically over the entire image.  Supported values for ch: 4|Kahan
int dt_box_mean_vertical(float *const buf, const size_t height, const size_t width, const int ch, const int radius);
 
int dt_box_min(float *const buf, const size_t height, const size_t width, const int ch, const int radius);
int dt_box_max(float *const buf, const size_t height, const size_t width, const int ch, const int radius);
 
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