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Diffstat (limited to 'media/libjxl/src/lib/jxl/dec_xyb-inl.h')
| -rw-r--r-- | media/libjxl/src/lib/jxl/dec_xyb-inl.h | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/media/libjxl/src/lib/jxl/dec_xyb-inl.h b/media/libjxl/src/lib/jxl/dec_xyb-inl.h new file mode 100644 index 0000000000..344b4cfe6c --- /dev/null +++ b/media/libjxl/src/lib/jxl/dec_xyb-inl.h @@ -0,0 +1,341 @@ +// Copyright (c) the JPEG XL Project Authors. All rights reserved. +// +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// XYB -> linear sRGB helper function. + +#if defined(LIB_JXL_DEC_XYB_INL_H_) == defined(HWY_TARGET_TOGGLE) +#ifdef LIB_JXL_DEC_XYB_INL_H_ +#undef LIB_JXL_DEC_XYB_INL_H_ +#else +#define LIB_JXL_DEC_XYB_INL_H_ +#endif + +#include <hwy/highway.h> + +#include "lib/jxl/dec_xyb.h" +HWY_BEFORE_NAMESPACE(); +namespace jxl { +namespace HWY_NAMESPACE { +namespace { + +// These templates are not found via ADL. +using hwy::HWY_NAMESPACE::Broadcast; + +// Inverts the pixel-wise RGB->XYB conversion in OpsinDynamicsImage() (including +// the gamma mixing and simple gamma). Avoids clamping to [0, 1] - out of (sRGB) +// gamut values may be in-gamut after transforming to a wider space. +// "inverse_matrix" points to 9 broadcasted vectors, which are the 3x3 entries +// of the (row-major) opsin absorbance matrix inverse. Pre-multiplying its +// entries by c is equivalent to multiplying linear_* by c afterwards. +template <class D, class V> +HWY_INLINE HWY_MAYBE_UNUSED void XybToRgb(D d, const V opsin_x, const V opsin_y, + const V opsin_b, + const OpsinParams& opsin_params, + V* const HWY_RESTRICT linear_r, + V* const HWY_RESTRICT linear_g, + V* const HWY_RESTRICT linear_b) { +#if HWY_TARGET == HWY_SCALAR + const auto neg_bias_r = Set(d, opsin_params.opsin_biases[0]); + const auto neg_bias_g = Set(d, opsin_params.opsin_biases[1]); + const auto neg_bias_b = Set(d, opsin_params.opsin_biases[2]); +#else + const auto neg_bias_rgb = LoadDup128(d, opsin_params.opsin_biases); + const auto neg_bias_r = Broadcast<0>(neg_bias_rgb); + const auto neg_bias_g = Broadcast<1>(neg_bias_rgb); + const auto neg_bias_b = Broadcast<2>(neg_bias_rgb); +#endif + + // Color space: XYB -> RGB + auto gamma_r = opsin_y + opsin_x; + auto gamma_g = opsin_y - opsin_x; + auto gamma_b = opsin_b; + + gamma_r -= Set(d, opsin_params.opsin_biases_cbrt[0]); + gamma_g -= Set(d, opsin_params.opsin_biases_cbrt[1]); + gamma_b -= Set(d, opsin_params.opsin_biases_cbrt[2]); + + // Undo gamma compression: linear = gamma^3 for efficiency. + const auto gamma_r2 = gamma_r * gamma_r; + const auto gamma_g2 = gamma_g * gamma_g; + const auto gamma_b2 = gamma_b * gamma_b; + const auto mixed_r = MulAdd(gamma_r2, gamma_r, neg_bias_r); + const auto mixed_g = MulAdd(gamma_g2, gamma_g, neg_bias_g); + const auto mixed_b = MulAdd(gamma_b2, gamma_b, neg_bias_b); + + const float* HWY_RESTRICT inverse_matrix = opsin_params.inverse_opsin_matrix; + + // Unmix (multiply by 3x3 inverse_matrix) + *linear_r = LoadDup128(d, &inverse_matrix[0 * 4]) * mixed_r; + *linear_g = LoadDup128(d, &inverse_matrix[3 * 4]) * mixed_r; + *linear_b = LoadDup128(d, &inverse_matrix[6 * 4]) * mixed_r; + *linear_r = MulAdd(LoadDup128(d, &inverse_matrix[1 * 4]), mixed_g, *linear_r); + *linear_g = MulAdd(LoadDup128(d, &inverse_matrix[4 * 4]), mixed_g, *linear_g); + *linear_b = MulAdd(LoadDup128(d, &inverse_matrix[7 * 4]), mixed_g, *linear_b); + *linear_r = MulAdd(LoadDup128(d, &inverse_matrix[2 * 4]), mixed_b, *linear_r); + *linear_g = MulAdd(LoadDup128(d, &inverse_matrix[5 * 4]), mixed_b, *linear_g); + *linear_b = MulAdd(LoadDup128(d, &inverse_matrix[8 * 4]), mixed_b, *linear_b); +} + +static inline HWY_MAYBE_UNUSED bool HasFastXYBTosRGB8() { +#if HWY_TARGET == HWY_NEON + return true; +#else + return false; +#endif +} + +static inline HWY_MAYBE_UNUSED void FastXYBTosRGB8(const float* input[4], + uint8_t* output, + bool is_rgba, size_t xsize) { + // This function is very NEON-specific. As such, it uses intrinsics directly. +#if HWY_TARGET == HWY_NEON + // WARNING: doing fixed point arithmetic correctly is very complicated. + // Changes to this function should be thoroughly tested. + + // Note that the input is assumed to have 13 bits of mantissa, and the output + // will have 14 bits. + auto srgb_tf = [&](int16x8_t v16) { + int16x8_t clz = vclzq_s16(v16); + // Convert to [0.25, 0.5) range. + int16x8_t v025_05_16 = vqshlq_s16(v16, vqsubq_s16(clz, vdupq_n_s16(2))); + + // third degree polynomial approximation between 0.25 and 0.5 + // of 1.055/2^(7/2.4) * x^(1/2.4) / 32. + // poly ~ ((0.95x-1.75)*x+1.72)*x+0.29 + // We actually compute ~ ((0.47x-0.87)*x+0.86)*(2x)+0.29 as 1.75 and 1.72 + // overflow our fixed point representation. + + int16x8_t twov = vqaddq_s16(v025_05_16, v025_05_16); + + // 0.47 * x + int16x8_t step1 = vqrdmulhq_n_s16(v025_05_16, 15706); + // - 0.87 + int16x8_t step2 = vsubq_s16(step1, vdupq_n_s16(28546)); + // * x + int16x8_t step3 = vqrdmulhq_s16(step2, v025_05_16); + // + 0.86 + int16x8_t step4 = vaddq_s16(step3, vdupq_n_s16(28302)); + // * 2x + int16x8_t step5 = vqrdmulhq_s16(step4, twov); + // + 0.29 + int16x8_t mul16 = vaddq_s16(step5, vdupq_n_s16(9485)); + + int16x8_t exp16 = vsubq_s16(vdupq_n_s16(11), clz); + // Compute 2**(1/2.4*exp16)/32. Values of exp16 that would overflow are + // capped to 1. + // Generated with the following Python script: + // a = [] + // b = [] + // + // for i in range(0, 16): + // v = 2**(5/12.*i) + // v /= 16 + // v *= 256 * 128 + // v = int(v) + // a.append(v // 256) + // b.append(v % 256) + // + // print(", ".join("0x%02x" % x for x in a)) + // + // print(", ".join("0x%02x" % x for x in b)) + + HWY_ALIGN constexpr uint8_t k2to512powersm1div32_high[16] = { + 0x08, 0x0a, 0x0e, 0x13, 0x19, 0x21, 0x2d, 0x3c, + 0x50, 0x6b, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, 0x8f, + }; + HWY_ALIGN constexpr uint8_t k2to512powersm1div32_low[16] = { + 0x00, 0xad, 0x41, 0x06, 0x65, 0xe7, 0x41, 0x68, + 0xa2, 0xa2, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + }; + // Using the highway implementation here since vqtbl1q is aarch64-only. + using hwy::HWY_NAMESPACE::Vec128; + uint8x16_t pow_low = + TableLookupBytes( + Vec128<uint8_t, 16>(vld1q_u8(k2to512powersm1div32_low)), + Vec128<uint8_t, 16>(vreinterpretq_u8_s16(exp16))) + .raw; + uint8x16_t pow_high = + TableLookupBytes( + Vec128<uint8_t, 16>(vld1q_u8(k2to512powersm1div32_high)), + Vec128<uint8_t, 16>(vreinterpretq_u8_s16(exp16))) + .raw; + int16x8_t pow16 = vreinterpretq_s16_u16(vsliq_n_u16( + vreinterpretq_u16_u8(pow_low), vreinterpretq_u16_u8(pow_high), 8)); + + // approximation of v * 12.92, divided by 2 + // Note that our input is using 13 mantissa bits instead of 15. + int16x8_t v16_linear = vrshrq_n_s16(vmulq_n_s16(v16, 826), 5); + // 1.055*pow(v, 1/2.4) - 0.055, divided by 2 + auto v16_pow = vsubq_s16(vqrdmulhq_s16(mul16, pow16), vdupq_n_s16(901)); + // > 0.0031308f (note that v16 has 13 mantissa bits) + return vbslq_s16(vcgeq_s16(v16, vdupq_n_s16(26)), v16_pow, v16_linear); + }; + + const float* JXL_RESTRICT row_in_x = input[0]; + const float* JXL_RESTRICT row_in_y = input[1]; + const float* JXL_RESTRICT row_in_b = input[2]; + const float* JXL_RESTRICT row_in_a = input[3]; + for (size_t x = 0; x < xsize; x += 8) { + // Normal ranges for xyb for in-gamut sRGB colors: + // x: -0.015386 0.028100 + // y: 0.000000 0.845308 + // b: 0.000000 0.845308 + + // We actually want x * 8 to have some extra precision. + // TODO(veluca): consider different approaches here, like vld1q_f32_x2. + float32x4_t opsin_x_left = vld1q_f32(row_in_x + x); + int16x4_t opsin_x16_times8_left = + vqmovn_s32(vcvtq_n_s32_f32(opsin_x_left, 18)); + float32x4_t opsin_x_right = + vld1q_f32(row_in_x + x + (x + 4 < xsize ? 4 : 0)); + int16x4_t opsin_x16_times8_right = + vqmovn_s32(vcvtq_n_s32_f32(opsin_x_right, 18)); + int16x8_t opsin_x16_times8 = + vcombine_s16(opsin_x16_times8_left, opsin_x16_times8_right); + + float32x4_t opsin_y_left = vld1q_f32(row_in_y + x); + int16x4_t opsin_y16_left = vqmovn_s32(vcvtq_n_s32_f32(opsin_y_left, 15)); + float32x4_t opsin_y_right = + vld1q_f32(row_in_y + x + (x + 4 < xsize ? 4 : 0)); + int16x4_t opsin_y16_right = vqmovn_s32(vcvtq_n_s32_f32(opsin_y_right, 15)); + int16x8_t opsin_y16 = vcombine_s16(opsin_y16_left, opsin_y16_right); + + float32x4_t opsin_b_left = vld1q_f32(row_in_b + x); + int16x4_t opsin_b16_left = vqmovn_s32(vcvtq_n_s32_f32(opsin_b_left, 15)); + float32x4_t opsin_b_right = + vld1q_f32(row_in_b + x + (x + 4 < xsize ? 4 : 0)); + int16x4_t opsin_b16_right = vqmovn_s32(vcvtq_n_s32_f32(opsin_b_right, 15)); + int16x8_t opsin_b16 = vcombine_s16(opsin_b16_left, opsin_b16_right); + + int16x8_t neg_bias16 = vdupq_n_s16(-124); // -0.0037930732552754493 + int16x8_t neg_bias_cbrt16 = vdupq_n_s16(-5110); // -0.155954201 + int16x8_t neg_bias_half16 = vdupq_n_s16(-62); + + // Color space: XYB -> RGB + // Compute ((y+x-bias_cbrt)^3-(y-x-bias_cbrt)^3)/2, + // ((y+x-bias_cbrt)^3+(y-x-bias_cbrt)^3)/2+bias, (b-bias_cbrt)^3+bias. + // Note that ignoring x2 in the formulas below (as x << y) results in + // errors of at least 3 in the final sRGB values. + int16x8_t opsin_yp16 = vqsubq_s16(opsin_y16, neg_bias_cbrt16); + int16x8_t ysq16 = vqrdmulhq_s16(opsin_yp16, opsin_yp16); + int16x8_t twentyfourx16 = vmulq_n_s16(opsin_x16_times8, 3); + int16x8_t twentyfourxy16 = vqrdmulhq_s16(opsin_yp16, twentyfourx16); + int16x8_t threexsq16 = + vrshrq_n_s16(vqrdmulhq_s16(opsin_x16_times8, twentyfourx16), 6); + + // We can ignore x^3 here. Note that this is multiplied by 8. + int16x8_t mixed_rmg16 = vqrdmulhq_s16(twentyfourxy16, opsin_yp16); + + int16x8_t mixed_rpg_sos_half = vhaddq_s16(ysq16, threexsq16); + int16x8_t mixed_rpg16 = vhaddq_s16( + vqrdmulhq_s16(opsin_yp16, mixed_rpg_sos_half), neg_bias_half16); + + int16x8_t gamma_b16 = vqsubq_s16(opsin_b16, neg_bias_cbrt16); + int16x8_t gamma_bsq16 = vqrdmulhq_s16(gamma_b16, gamma_b16); + int16x8_t gamma_bcb16 = vqrdmulhq_s16(gamma_bsq16, gamma_b16); + int16x8_t mixed_b16 = vqaddq_s16(gamma_bcb16, neg_bias16); + // mixed_rpg and mixed_b are in 0-1 range. + // mixed_rmg has a smaller range (-0.035 to 0.035 for valid sRGB). Note + // that at this point it is already multiplied by 8. + + // We multiply all the mixed values by 1/4 (i.e. shift them to 13-bit + // fixed point) to ensure intermediate quantities are in range. Note that + // r-g is not shifted, and was x8 before here; this corresponds to a x32 + // overall multiplicative factor and ensures that all the matrix constants + // are in 0-1 range. + // Similarly, mixed_rpg16 is already multiplied by 1/4 because of the two + // vhadd + using neg_bias_half. + mixed_b16 = vshrq_n_s16(mixed_b16, 2); + + // Unmix (multiply by 3x3 inverse_matrix) + // For increased precision, we use a matrix for converting from + // ((mixed_r - mixed_g)/2, (mixed_r + mixed_g)/2, mixed_b) to rgb. This + // avoids cancellation effects when computing (y+x)^3-(y-x)^3. + // We compute mixed_rpg - mixed_b because the (1+c)*mixed_rpg - c * + // mixed_b pattern is repeated frequently in the code below. This allows + // us to save a multiply per channel, and removes the presence of + // some constants above 1. Moreover, mixed_rmg - mixed_b is in (-1, 1) + // range, so the subtraction is safe. + // All the magic-looking constants here are derived by computing the + // inverse opsin matrix for the transformation modified as described + // above. + + // Precomputation common to multiple color values. + int16x8_t mixed_rpgmb16 = vqsubq_s16(mixed_rpg16, mixed_b16); + int16x8_t mixed_rpgmb_times_016 = vqrdmulhq_n_s16(mixed_rpgmb16, 5394); + int16x8_t mixed_rg16 = vqaddq_s16(mixed_rpgmb_times_016, mixed_rpg16); + + // R + int16x8_t linear_r16 = + vqaddq_s16(mixed_rg16, vqrdmulhq_n_s16(mixed_rmg16, 21400)); + + // G + int16x8_t linear_g16 = + vqaddq_s16(mixed_rg16, vqrdmulhq_n_s16(mixed_rmg16, -7857)); + + // B + int16x8_t linear_b16 = vqrdmulhq_n_s16(mixed_rpgmb16, -30996); + linear_b16 = vqaddq_s16(linear_b16, mixed_b16); + linear_b16 = vqaddq_s16(linear_b16, vqrdmulhq_n_s16(mixed_rmg16, -6525)); + + // Apply SRGB transfer function. + int16x8_t r = srgb_tf(linear_r16); + int16x8_t g = srgb_tf(linear_g16); + int16x8_t b = srgb_tf(linear_b16); + + uint8x8_t r8 = + vqmovun_s16(vrshrq_n_s16(vsubq_s16(r, vshrq_n_s16(r, 8)), 6)); + uint8x8_t g8 = + vqmovun_s16(vrshrq_n_s16(vsubq_s16(g, vshrq_n_s16(g, 8)), 6)); + uint8x8_t b8 = + vqmovun_s16(vrshrq_n_s16(vsubq_s16(b, vshrq_n_s16(b, 8)), 6)); + + size_t n = xsize - x; + if (is_rgba) { + float32x4_t a_f32_left = + row_in_a ? vld1q_f32(row_in_a + x) : vdupq_n_f32(1.0f); + float32x4_t a_f32_right = + row_in_a ? vld1q_f32(row_in_a + x + (x + 4 < xsize ? 4 : 0)) + : vdupq_n_f32(1.0f); + int16x4_t a16_left = vqmovn_s32(vcvtq_n_s32_f32(a_f32_left, 8)); + int16x4_t a16_right = vqmovn_s32(vcvtq_n_s32_f32(a_f32_right, 8)); + uint8x8_t a8 = vqmovun_s16(vcombine_s16(a16_left, a16_right)); + uint8_t* buf = output + 4 * x; + uint8x8x4_t data = {r8, g8, b8, a8}; + if (n >= 8) { + vst4_u8(buf, data); + } else { + uint8_t tmp[8 * 4]; + vst4_u8(tmp, data); + memcpy(buf, tmp, n * 4); + } + } else { + uint8_t* buf = output + 3 * x; + uint8x8x3_t data = {r8, g8, b8}; + if (n >= 8) { + vst3_u8(buf, data); + } else { + uint8_t tmp[8 * 3]; + vst3_u8(tmp, data); + memcpy(buf, tmp, n * 3); + } + } + } +#else + (void)input; + (void)output; + (void)is_rgba; + (void)xsize; + JXL_ABORT("Unreachable"); +#endif +} + +} // namespace +// NOLINTNEXTLINE(google-readability-namespace-comments) +} // namespace HWY_NAMESPACE +} // namespace jxl +HWY_AFTER_NAMESPACE(); + +#endif // LIB_JXL_DEC_XYB_INL_H_ |