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#pragma once
// Bayer raw read/write support.
//
// Write side: each pixel carries one of R/G/B selected by (x mod 2,
// y mod 2) and a fixed BayerOrder. Two missing channels per pixel are
// dropped on encode.
//
// Read side: bilinear demosaic over a 3x3 window. The pixel's own
// channel comes from self; missing channels are averaged from the
// same-channel neighbours that the Bayer phase guarantees to exist:
//
// * At an R or B pixel, all four cardinal (N, E, S, W) neighbours
// carry G and all four diagonal (NE, NW, SE, SW) neighbours carry
// the other colour, so each missing channel averages four samples.
// * At a G pixel, one missing colour sits in the row neighbours
// (W, E) and the other in the column neighbours (N, S), so each
// missing channel averages two samples.
//
// Sampled coordinates are clamped to the image bounds.
//
// The Layout shape is the same as a Y-only single-plane format
// (storage carries one component plus optional X padding); the
// BayerOrder is a separate template parameter on the Source / Sink.
#include <array>
#include <cstdint>
#include "../layout.h"
#include "csi2.h"
#include "detail.h"
namespace pixpat
{
enum class BayerOrder { RGGB, BGGR, GRBG, GBRG };
namespace detail
{
constexpr C bayer_pick(BayerOrder o, bool x_even, bool y_even) noexcept
{
switch (o) {
case BayerOrder::RGGB:
return y_even ? (x_even ? C::R : C::G)
: (x_even ? C::G : C::B);
case BayerOrder::BGGR:
return y_even ? (x_even ? C::B : C::G)
: (x_even ? C::G : C::R);
case BayerOrder::GRBG:
return y_even ? (x_even ? C::G : C::R)
: (x_even ? C::B : C::G);
case BayerOrder::GBRG:
return y_even ? (x_even ? C::G : C::B)
: (x_even ? C::R : C::G);
}
return C::G;
}
constexpr size_t clamp_coord(int v, size_t max_excl) noexcept
{
if (v < 0)
return 0;
if (size_t(v) >= max_excl)
return max_excl - 1;
return size_t(v);
}
} // namespace detail
template <typename L, BayerOrder Order>
struct BayerSource {
using Layout = L;
using Pixel = RGB16;
static_assert(L::kind == ColorKind::RGB);
static_assert(L::num_planes == 1);
using P = typename L::template plane<0>;
static constexpr size_t y_idx = P::template find_pos<C::Y>();
static_assert(y_idx < P::num_comps);
static uint16_t read_sample(const Buffer<1>& buf, size_t x, size_t y) noexcept
{
const uint8_t* p = buf.data[0] + y * buf.stride[0]
+ x * P::bytes_per_pixel;
const auto vals = P::unpack(detail::load_word<P>(p));
return detail::decode_norm(P::comps[y_idx].bits, vals[y_idx]);
}
static RGB16 read(const Buffer<1>& buf, size_t x, size_t y,
size_t W, size_t H) noexcept
{
const bool x_even = (x & 1) == 0;
const bool y_even = (y & 1) == 0;
const C self = detail::bayer_pick(Order, x_even, y_even);
const size_t xL = detail::clamp_coord(int(x) - 1, W);
const size_t xR = detail::clamp_coord(int(x) + 1, W);
const size_t yT = detail::clamp_coord(int(y) - 1, H);
const size_t yB = detail::clamp_coord(int(y) + 1, H);
const uint16_t s = read_sample(buf, x, y);
uint16_t r = 0, g = 0, b = 0;
if (self == C::G) {
const C h_color = detail::bayer_pick(Order, !x_even, y_even);
const uint16_t h_avg = uint16_t(
(uint32_t(read_sample(buf, xL, y))
+ read_sample(buf, xR, y) + 1u) >> 1);
const uint16_t v_avg = uint16_t(
(uint32_t(read_sample(buf, x, yT))
+ read_sample(buf, x, yB) + 1u) >> 1);
g = s;
if (h_color == C::R) { r = h_avg; b = v_avg; }
else { b = h_avg; r = v_avg; }
} else {
const uint16_t g_avg = uint16_t(
(uint32_t(read_sample(buf, x, yT))
+ read_sample(buf, x, yB)
+ read_sample(buf, xL, y)
+ read_sample(buf, xR, y) + 2u) >> 2);
const uint16_t o_avg = uint16_t(
(uint32_t(read_sample(buf, xL, yT))
+ read_sample(buf, xR, yT)
+ read_sample(buf, xL, yB)
+ read_sample(buf, xR, yB) + 2u) >> 2);
g = g_avg;
if (self == C::R) { r = s; b = o_avg; }
else { b = s; r = o_avg; }
}
return RGB16{ r, g, b, uint16_t(0) };
}
};
template <typename L, BayerOrder Order>
struct BayerSink {
using Layout = L;
using Pixel = RGB16;
static_assert(L::kind == ColorKind::RGB);
static_assert(L::num_planes == 1);
using P = typename L::template plane<0>;
static constexpr size_t y_idx = P::template find_pos<C::Y>();
static constexpr size_t x_idx = P::template find_pos<C::X>();
static constexpr bool has_x = (x_idx < P::num_comps);
static_assert(y_idx < P::num_comps);
static constexpr size_t block_h = 1;
static constexpr size_t block_w = 1;
static void write_block(Buffer<1>& buf, size_t bx, size_t by,
const RGB16 (&block)[1][1]) noexcept
{
const C pick = detail::bayer_pick(Order, (bx & 1) == 0,
(by & 1) == 0);
const uint16_t val = pick == C::R ? block[0][0].r
: pick == C::G ? block[0][0].g
: block[0][0].b;
std::array<uint16_t, P::num_comps> v{};
v[y_idx] = detail::encode_norm(P::comps[y_idx].bits, val);
if constexpr (has_x)
v[x_idx] = 0;
uint8_t* p = buf.data[0] + by * buf.stride[0]
+ bx * P::bytes_per_pixel;
detail::store_word<P>(p, P::pack(v));
}
};
// Aliases so X-macro can register without nested template-template params.
template <typename L> using BayerSource_RGGB = BayerSource<L, BayerOrder::RGGB>;
template <typename L> using BayerSource_BGGR = BayerSource<L, BayerOrder::BGGR>;
template <typename L> using BayerSource_GRBG = BayerSource<L, BayerOrder::GRBG>;
template <typename L> using BayerSource_GBRG = BayerSource<L, BayerOrder::GBRG>;
template <typename L> using BayerSink_RGGB = BayerSink<L, BayerOrder::RGGB>;
template <typename L> using BayerSink_BGGR = BayerSink<L, BayerOrder::BGGR>;
template <typename L> using BayerSink_GRBG = BayerSink<L, BayerOrder::GRBG>;
template <typename L> using BayerSink_GBRG = BayerSink<L, BayerOrder::GBRG>;
// MIPI CSI-2 packed Bayer. The bit layout doesn't fit
// `Plane<Storage, Comp...>` because each pixel's bits span two
// non-contiguous bytes, so we use the shared CSI-2 helper (io/csi2.h)
// to (un)pack samples.
//
// The Layout slot is a placeholder (matches the unpacked Bayer of the
// same bit-depth so the user-facing API can pick the right buffer
// shape); bytes_per_pixel from the Plane is unused.
template <typename L, BayerOrder Order, size_t BitDepth>
struct BayerPackedSource {
using Layout = L;
using Pixel = RGB16;
static_assert(L::kind == ColorKind::RGB);
static_assert(L::num_planes == 1);
static_assert(BitDepth == 10 || BitDepth == 12);
using Traits = detail::csi2::packed_traits<BitDepth>;
static constexpr size_t ppg = Traits::ppg;
static constexpr size_t bpg = Traits::bpg;
// Stored N-bit value upshifts to normalized-16 by `<< (16-N)`,
// matching the unpacked Bayer source.
static constexpr unsigned shift = 16 - BitDepth;
static uint16_t read_sample(const Buffer<1>& buf, size_t x, size_t y) noexcept
{
const uint8_t* src = buf.data[0] + y * buf.stride[0]
+ (x / ppg) * bpg;
const uint16_t val = detail::csi2::unpack_sample<BitDepth>(src, x % ppg);
return uint16_t(val << shift);
}
static RGB16 read(const Buffer<1>& buf, size_t x, size_t y,
size_t W, size_t H) noexcept
{
const bool x_even = (x & 1) == 0;
const bool y_even = (y & 1) == 0;
const C self = detail::bayer_pick(Order, x_even, y_even);
const size_t xL = detail::clamp_coord(int(x) - 1, W);
const size_t xR = detail::clamp_coord(int(x) + 1, W);
const size_t yT = detail::clamp_coord(int(y) - 1, H);
const size_t yB = detail::clamp_coord(int(y) + 1, H);
const uint16_t s = read_sample(buf, x, y);
uint16_t r = 0, g = 0, b = 0;
if (self == C::G) {
const C h_color = detail::bayer_pick(Order, !x_even, y_even);
const uint16_t h_avg = uint16_t(
(uint32_t(read_sample(buf, xL, y))
+ read_sample(buf, xR, y) + 1u) >> 1);
const uint16_t v_avg = uint16_t(
(uint32_t(read_sample(buf, x, yT))
+ read_sample(buf, x, yB) + 1u) >> 1);
g = s;
if (h_color == C::R) { r = h_avg; b = v_avg; }
else { b = h_avg; r = v_avg; }
} else {
const uint16_t g_avg = uint16_t(
(uint32_t(read_sample(buf, x, yT))
+ read_sample(buf, x, yB)
+ read_sample(buf, xL, y)
+ read_sample(buf, xR, y) + 2u) >> 2);
const uint16_t o_avg = uint16_t(
(uint32_t(read_sample(buf, xL, yT))
+ read_sample(buf, xR, yT)
+ read_sample(buf, xL, yB)
+ read_sample(buf, xR, yB) + 2u) >> 2);
g = g_avg;
if (self == C::R) { r = s; b = o_avg; }
else { b = s; r = o_avg; }
}
return RGB16{ r, g, b, uint16_t(0) };
}
};
template <typename L, BayerOrder Order, size_t BitDepth>
struct BayerPackedSink {
using Layout = L;
using Pixel = RGB16;
static_assert(L::kind == ColorKind::RGB);
static_assert(L::num_planes == 1);
static_assert(BitDepth == 10 || BitDepth == 12);
using Traits = detail::csi2::packed_traits<BitDepth>;
static constexpr size_t ppg = Traits::ppg;
static constexpr size_t bpg = Traits::bpg;
static constexpr size_t block_h = 1;
static constexpr size_t block_w = ppg;
static void write_block(Buffer<1>& buf, size_t bx, size_t by,
const RGB16 (&block)[1][ppg]) noexcept
{
std::array<uint16_t, ppg> vals{};
for (size_t i = 0; i < ppg; ++i) {
const C pick = detail::bayer_pick(
Order, ((bx + i) & 1) == 0, (by & 1) == 0);
const uint16_t norm =
pick == C::R ? block[0][i].r
: pick == C::G ? block[0][i].g
: block[0][i].b;
vals[i] = uint16_t(norm >> (16 - BitDepth));
}
uint8_t* dst = buf.data[0] + by * buf.stride[0]
+ (bx / ppg) * bpg;
detail::csi2::pack_group<BitDepth>(dst, vals);
}
};
template <typename L> using BayerPackedSource_RGGB10 = BayerPackedSource<L, BayerOrder::RGGB, 10>;
template <typename L> using BayerPackedSource_BGGR10 = BayerPackedSource<L, BayerOrder::BGGR, 10>;
template <typename L> using BayerPackedSource_GRBG10 = BayerPackedSource<L, BayerOrder::GRBG, 10>;
template <typename L> using BayerPackedSource_GBRG10 = BayerPackedSource<L, BayerOrder::GBRG, 10>;
template <typename L> using BayerPackedSource_RGGB12 = BayerPackedSource<L, BayerOrder::RGGB, 12>;
template <typename L> using BayerPackedSource_BGGR12 = BayerPackedSource<L, BayerOrder::BGGR, 12>;
template <typename L> using BayerPackedSource_GRBG12 = BayerPackedSource<L, BayerOrder::GRBG, 12>;
template <typename L> using BayerPackedSource_GBRG12 = BayerPackedSource<L, BayerOrder::GBRG, 12>;
template <typename L> using BayerPackedSink_RGGB10 = BayerPackedSink<L, BayerOrder::RGGB, 10>;
template <typename L> using BayerPackedSink_BGGR10 = BayerPackedSink<L, BayerOrder::BGGR, 10>;
template <typename L> using BayerPackedSink_GRBG10 = BayerPackedSink<L, BayerOrder::GRBG, 10>;
template <typename L> using BayerPackedSink_GBRG10 = BayerPackedSink<L, BayerOrder::GBRG, 10>;
template <typename L> using BayerPackedSink_RGGB12 = BayerPackedSink<L, BayerOrder::RGGB, 12>;
template <typename L> using BayerPackedSink_BGGR12 = BayerPackedSink<L, BayerOrder::BGGR, 12>;
template <typename L> using BayerPackedSink_GRBG12 = BayerPackedSink<L, BayerOrder::GRBG, 12>;
template <typename L> using BayerPackedSink_GBRG12 = BayerPackedSink<L, BayerOrder::GBRG, 12>;
} // namespace pixpat
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