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/*
* This file is part of libplacebo.
*
* libplacebo 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.
*
* libplacebo 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 libplacebo. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LIBPLACEBO_DITHER_H_
#define LIBPLACEBO_DITHER_H_
#include <libplacebo/common.h>
PL_API_BEGIN
// Generates a deterministic NxN bayer (ordered) dither matrix, storing the
// result in `data`. `size` must be a power of two. The resulting matrix will
// be roughly uniformly distributed within the range [0,1).
PL_API void pl_generate_bayer_matrix(float *data, int size);
// Generates a random NxN blue noise texture. storing the result in `data`.
// `size` must be a positive power of two no larger than 256. The resulting
// texture will be roughly uniformly distributed within the range [0,1).
//
// Note: This function is very, *very* slow for large sizes. Generating a
// dither matrix with size 256 can take several seconds on a modern processor.
PL_API void pl_generate_blue_noise(float *data, int size);
// Defines the border of all error diffusion kernels
#define PL_EDF_MIN_DX (-2)
#define PL_EDF_MAX_DX (2)
#define PL_EDF_MAX_DY (2)
struct pl_error_diffusion_kernel {
const char *name; // Short and concise identifier
const char *description; // Longer / friendly name
// The minimum value such that a (y, x) -> (y, x + y * shift) mapping will
// make all error pushing operations affect next column (and after it)
// only.
//
// Higher shift values are significantly more computationally intensive.
int shift;
// The diffusion factor for (y, x) is pattern[y][x - PL_EDF_MIN_DX] / divisor.
int pattern[PL_EDF_MAX_DY + 1][PL_EDF_MAX_DX - PL_EDF_MIN_DX + 1];
int divisor;
};
// Algorithms with shift=1:
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_simple;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_false_fs;
// Algorithms with shift=2:
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_sierra_lite;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_floyd_steinberg;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_atkinson;
// Algorithms with shift=3, probably too heavy for low end GPUs:
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_jarvis_judice_ninke;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_stucki;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_burkes;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_sierra2;
PL_API extern const struct pl_error_diffusion_kernel pl_error_diffusion_sierra3;
// A list of built-in error diffusion kernels, terminated by NULL
PL_API extern const struct pl_error_diffusion_kernel * const pl_error_diffusion_kernels[];
PL_API extern const int pl_num_error_diffusion_kernels; // excluding trailing NULL
// Find the error diffusion kernel with the given name, or NULL on failure.
PL_API const struct pl_error_diffusion_kernel *pl_find_error_diffusion_kernel(const char *name);
PL_API_END
#endif // LIBPLACEBO_DITHER_H_
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