gp_gamma_correction.h

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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * Copyright (C) 2009-2024 Cyril Hrubis <metan@ucw.cz>
 */
 
#ifndef CORE_GP_GAMMA_CORRECTION_H
#define CORE_GP_GAMMA_CORRECTION_H
 
#include <stdint.h>
#include <core/gp_types.h>
#include <core/gp_pixel.gen.h>
#include <core/gp_gamma_correction.gen.h>
 
typedef enum gp_correction_type {
        GP_CORRECTION_TYPE_GAMMA,
        GP_CORRECTION_TYPE_SRGB,
} gp_correction_type;
 
typedef struct gp_correction_desc {
        gp_correction_type corr_type;
        float gamma;
} gp_correction_desc;
 
typedef struct gp_gamma_table {
        gp_correction_type corr_type;
        float gamma;
 
        uint8_t in_bits;
        uint8_t out_bits;
 
        unsigned int ref_count;
        struct gp_gamma_table *next;
 
        union {
                uint8_t u8[0];
                uint16_t u16[0];
        };
} gp_gamma_table;
 
typedef struct gp_gamma {
        gp_pixel_type pixel_type;
 
        unsigned int ref_count;
 
        gp_gamma_table *lin[GP_PIXEL_CHANS_MAX];
        gp_gamma_table *enc[GP_PIXEL_CHANS_MAX];
} gp_gamma;
 
gp_gamma *gp_correction_acquire(gp_pixel_type pixel_type,
                                gp_correction_desc *corr_desc);
 
gp_gamma *gp_gamma_incref(gp_gamma *gamma);
 
void gp_gamma_decref(gp_gamma *self);
 
const char *gp_correction_type_name(gp_correction_type type);
 
void gp_gamma_print(const gp_gamma *self);
 
/* Generated sRGB lookup tables */
extern uint16_t gp_srgb8_to_lin10_tbl[256];
extern uint8_t gp_lin10_to_srgb8_tbl[1024];
 
static inline uint8_t gp_lin16_to_srgb8(uint16_t val)
{
        return gp_lin10_to_srgb8_tbl[(val + (1<<3))>>6];
}
 
static inline uint16_t gp_srgb8_to_lin16(uint8_t val)
{
        return gp_srgb8_to_lin10_tbl[val]<<6;
}
 
#endif /* CORE_GP_GAMMA_CORRECTION_H */