diff options
Diffstat (limited to 'libavutil/csp.h')
| -rw-r--r-- | libavutil/csp.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/libavutil/csp.h b/libavutil/csp.h index 18ef208adf..73bce52bc0 100644 --- a/libavutil/csp.h +++ b/libavutil/csp.h @@ -1,5 +1,8 @@ /* + * Copyright (c) 2015 Kevin Wheatley <kevin.j.wheatley@gmail.com> * Copyright (c) 2016 Ronald S. Bultje <rsbultje@gmail.com> + * Copyright (c) 2023 Leo Izen <leo.izen@gmail.com> + * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or @@ -29,6 +32,7 @@ * @ingroup lavu_math_csp * @author Ronald S. Bultje <rsbultje@gmail.com> * @author Leo Izen <leo.izen@gmail.com> + * @author Kevin Wheatley <kevin.j.wheatley@gmail.com> */ /** @@ -77,6 +81,12 @@ typedef struct AVColorPrimariesDesc { } AVColorPrimariesDesc; /** + * Function pointer representing a double -> double transfer function that performs + * an EOTF transfer inversion. This function outputs linear light. + */ +typedef double (*av_csp_trc_function)(double); + +/** * Retrieves the Luma coefficients necessary to construct a conversion matrix * from an enum constant describing the colorspace. * @param csp An enum constant indicating YUV or similar colorspace. @@ -105,6 +115,35 @@ const AVColorPrimariesDesc *av_csp_primaries_desc_from_id(enum AVColorPrimaries enum AVColorPrimaries av_csp_primaries_id_from_desc(const AVColorPrimariesDesc *prm); /** + * Determine a suitable 'gamma' value to match the supplied + * AVColorTransferCharacteristic. + * + * See Apple Technical Note TN2257 (https://developer.apple.com/library/mac/technotes/tn2257/_index.html) + * + * This function returns the gamma exponent for the OETF. For example, sRGB is approximated + * by gamma 2.2, not by gamma 0.45455. + * + * @return Will return an approximation to the simple gamma function matching + * the supplied Transfer Characteristic, Will return 0.0 for any + * we cannot reasonably match against. + */ +double av_csp_approximate_trc_gamma(enum AVColorTransferCharacteristic trc); + +/** + * Determine the function needed to apply the given + * AVColorTransferCharacteristic to linear input. + * + * The function returned should expect a nominal domain and range of [0.0-1.0] + * values outside of this range maybe valid depending on the chosen + * characteristic function. + * + * @return Will return pointer to the function matching the + * supplied Transfer Characteristic. If unspecified will + * return NULL: + */ +av_csp_trc_function av_csp_trc_func_from_id(enum AVColorTransferCharacteristic trc); + +/** * @} */ |