sharpyuv.h - mozsearch

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// Copyright 2022 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// Sharp RGB to YUV conversion.

#ifndef WEBP_SHARPYUV_SHARPYUV_H_

#define WEBP_SHARPYUV_SHARPYUV_H_

#ifdef __cplusplus

extern "C" {

#endif

#ifndef SHARPYUV_EXTERN

#ifdef WEBP_EXTERN

#define SHARPYUV_EXTERN WEBP_EXTERN

#else

// This explicitly marks library functions and allows for changing the

// signature for e.g., Windows DLL builds.

#if defined(_WIN32) && defined(WEBP_DLL)

#define SHARPYUV_EXTERN __declspec(dllexport)

#elif defined(__GNUC__) && __GNUC__ >= 4

#define SHARPYUV_EXTERN extern __attribute__((visibility("default")))

#else

#define SHARPYUV_EXTERN extern

#endif /* defined(_WIN32) && defined(WEBP_DLL) */

#endif /* WEBP_EXTERN */

#endif /* SHARPYUV_EXTERN */

#ifndef SHARPYUV_INLINE

#ifdef WEBP_INLINE

#define SHARPYUV_INLINE WEBP_INLINE

#else

#ifndef _MSC_VER

#if defined(__cplusplus) || !defined(__STRICT_ANSI__) || \

    (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)

#define SHARPYUV_INLINE inline

#else

#define SHARPYUV_INLINE

#endif

#else

#define SHARPYUV_INLINE __forceinline

#endif /* _MSC_VER */

#endif /* WEBP_INLINE */

#endif /* SHARPYUV_INLINE */

// SharpYUV API version following the convention from semver.org

#define SHARPYUV_VERSION_MAJOR 0

#define SHARPYUV_VERSION_MINOR 4

#define SHARPYUV_VERSION_PATCH 0

// Version as a uint32_t. The major number is the high 8 bits.

// The minor number is the middle 8 bits. The patch number is the low 16 bits.

#define SHARPYUV_MAKE_VERSION(MAJOR, MINOR, PATCH) \

  (((MAJOR) << 24) | ((MINOR) << 16) | (PATCH))

#define SHARPYUV_VERSION                                                \

  SHARPYUV_MAKE_VERSION(SHARPYUV_VERSION_MAJOR, SHARPYUV_VERSION_MINOR, \

                        SHARPYUV_VERSION_PATCH)

// Returns the library's version number, packed in hexadecimal. See

// SHARPYUV_VERSION.

SHARPYUV_EXTERN int SharpYuvGetVersion(void);

// RGB to YUV conversion matrix, in 16 bit fixed point.

// y = rgb_to_y[0] * r + rgb_to_y[1] * g + rgb_to_y[2] * b + rgb_to_y[3]

// u = rgb_to_u[0] * r + rgb_to_u[1] * g + rgb_to_u[2] * b + rgb_to_u[3]

// v = rgb_to_v[0] * r + rgb_to_v[1] * g + rgb_to_v[2] * b + rgb_to_v[3]

// Then y, u and v values are divided by 1<<16 and rounded.

typedef struct {

  int rgb_to_y[4];

  int rgb_to_u[4];

  int rgb_to_v[4];

} SharpYuvConversionMatrix;

typedef struct SharpYuvOptions SharpYuvOptions;

// Enums for transfer functions, as defined in H.273,

// https://www.itu.int/rec/T-REC-H.273-202107-I/en

typedef enum SharpYuvTransferFunctionType {

  // 0 is reserved

  kSharpYuvTransferFunctionBt709 = 1,

  // 2 is unspecified

  // 3 is reserved

  kSharpYuvTransferFunctionBt470M = 4,

  kSharpYuvTransferFunctionBt470Bg = 5,

  kSharpYuvTransferFunctionBt601 = 6,

  kSharpYuvTransferFunctionSmpte240 = 7,

  kSharpYuvTransferFunctionLinear = 8,

  kSharpYuvTransferFunctionLog100 = 9,

  kSharpYuvTransferFunctionLog100_Sqrt10 = 10,

  kSharpYuvTransferFunctionIec61966 = 11,

  kSharpYuvTransferFunctionBt1361 = 12,

  kSharpYuvTransferFunctionSrgb = 13,

  kSharpYuvTransferFunctionBt2020_10Bit = 14,

  kSharpYuvTransferFunctionBt2020_12Bit = 15,

  kSharpYuvTransferFunctionSmpte2084 = 16,  // PQ

  kSharpYuvTransferFunctionSmpte428 = 17,

  kSharpYuvTransferFunctionHlg = 18,

  kSharpYuvTransferFunctionNum

} SharpYuvTransferFunctionType;

// Converts RGB to YUV420 using a downsampling algorithm that minimizes

// artefacts caused by chroma subsampling.

// This is slower than standard downsampling (averaging of 4 UV values).

// Assumes that the image will be upsampled using a bilinear filter. If nearest

// neighbor is used instead, the upsampled image might look worse than with

// standard downsampling.

// r_ptr, g_ptr, b_ptr: pointers to the source r, g and b channels. Should point

//     to uint8_t buffers if rgb_bit_depth is 8, or uint16_t buffers otherwise.

// rgb_step: distance in bytes between two horizontally adjacent pixels on the

//     r, g and b channels. If rgb_bit_depth is > 8, it should be a

//     multiple of 2.

// rgb_stride: distance in bytes between two vertically adjacent pixels on the

//     r, g, and b channels. If rgb_bit_depth is > 8, it should be a

//     multiple of 2.

// rgb_bit_depth: number of bits for each r/g/b value. One of: 8, 10, 12, 16.

//     Note: 16 bit input is truncated to 14 bits before conversion to yuv.

// yuv_bit_depth: number of bits for each y/u/v value. One of: 8, 10, 12.

// y_ptr, u_ptr, v_ptr: pointers to the destination y, u and v channels.  Should

//     point to uint8_t buffers if yuv_bit_depth is 8, or uint16_t buffers

//     otherwise.

// y_stride, u_stride, v_stride: distance in bytes between two vertically

//     adjacent pixels on the y, u and v channels. If yuv_bit_depth > 8, they

//     should be multiples of 2.

// width, height: width and height of the image in pixels

// This function calls SharpYuvConvertWithOptions with a default transfer

// function of kSharpYuvTransferFunctionSrgb.

SHARPYUV_EXTERN int SharpYuvConvert(const void* r_ptr, const void* g_ptr,

                                    const void* b_ptr, int rgb_step,

                                    int rgb_stride, int rgb_bit_depth,

                                    void* y_ptr, int y_stride, void* u_ptr,

                                    int u_stride, void* v_ptr, int v_stride,

                                    int yuv_bit_depth, int width, int height,

                                    const SharpYuvConversionMatrix* yuv_matrix);

struct SharpYuvOptions {

  // This matrix cannot be NULL and can be initialized by

  // SharpYuvComputeConversionMatrix.

  const SharpYuvConversionMatrix* yuv_matrix;

  SharpYuvTransferFunctionType transfer_type;

};

// Internal, version-checked, entry point

SHARPYUV_EXTERN int SharpYuvOptionsInitInternal(const SharpYuvConversionMatrix*,

                                                SharpYuvOptions*, int);

// Should always be called, to initialize a fresh SharpYuvOptions

// structure before modification. SharpYuvOptionsInit() must have succeeded

// before using the 'options' object.

static SHARPYUV_INLINE int SharpYuvOptionsInit(

    const SharpYuvConversionMatrix* yuv_matrix, SharpYuvOptions* options) {

  return SharpYuvOptionsInitInternal(yuv_matrix, options, SHARPYUV_VERSION);

SHARPYUV_EXTERN int SharpYuvConvertWithOptions(

    const void* r_ptr, const void* g_ptr, const void* b_ptr, int rgb_step,

    int rgb_stride, int rgb_bit_depth, void* y_ptr, int y_stride, void* u_ptr,

    int u_stride, void* v_ptr, int v_stride, int yuv_bit_depth, int width,

    int height, const SharpYuvOptions* options);

// TODO(b/194336375): Add YUV444 to YUV420 conversion. Maybe also add 422

// support (it's rarely used in practice, especially for images).

#ifdef __cplusplus

}  // extern "C"

#endif

#endif  // WEBP_SHARPYUV_SHARPYUV_H_