applyGamma_video() [3/3]

fl::u8 fl::applyGamma_video	(	fl::u8	brightness,
		float	gamma )

Definition at line 1290 of file colorutils.cpp.hpp.

                                                    {
    // Fixed-point path (s16x16) avoids pulling `__ieee754_pow` (libm,
    // ~2.7 KB) into release builds — see #2886 / #2910. Matches the
    // gamma8 LUT generator's approach in src/fl/math/ease.cpp.hpp.
    if (brightness == 0) {
        return 0;
    }
    constexpr fl::s16x16 inv_255_fp(1.0f / 255.0f);
    const fl::s16x16 gamma_fp(gamma);
    const fl::s16x16 x = static_cast<i32>(brightness) * inv_255_fp;  // [0, 1]
    const fl::s16x16 r = fl::s16x16::pow(x, gamma_fp);                // (0, 1]
    // Scale to u8 [0, 255] with round-half-up:
    //   result = ((u32)raw * 255 + 0x8000) >> 16
    const fl::u32 scaled =
        (static_cast<fl::u32>(r.raw()) * 255u + 0x8000u) >> 16;
    fl::u8 result = static_cast<fl::u8>(scaled > 255u ? 255u : scaled);
    if (result == 0) {
        result = 1; // never gamma-adjust a positive number down to zero
    }
    return result;
}

References brightness, gamma(), fl::s16x16::pow(), fl::s16x16::raw(), and x.

Referenced by applyGamma_video(), applyGamma_video(), FL_DISABLE_WARNING(), napplyGamma_video(), napplyGamma_video(), napplyGamma_video(), and napplyGamma_video().

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