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// 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.
#include "lib/extras/dec/exr.h"
#include <ImfChromaticitiesAttribute.h>
#include <ImfIO.h>
#include <ImfRgbaFile.h>
#include <ImfStandardAttributes.h>
#include <vector>
namespace jxl {
namespace extras {
namespace {
namespace OpenEXR = OPENEXR_IMF_NAMESPACE;
namespace Imath = IMATH_NAMESPACE;
// OpenEXR::Int64 is deprecated in favor of using uint64_t directly, but using
// uint64_t as recommended causes build failures with previous OpenEXR versions
// on macOS, where the definition for OpenEXR::Int64 was actually not equivalent
// to uint64_t. This alternative should work in all cases.
using ExrInt64 = decltype(std::declval<OpenEXR::IStream>().tellg());
constexpr int kExrBitsPerSample = 16;
constexpr int kExrAlphaBits = 16;
class InMemoryIStream : public OpenEXR::IStream {
public:
// The data pointed to by `bytes` must outlive the InMemoryIStream.
explicit InMemoryIStream(const Span<const uint8_t> bytes)
: IStream(/*fileName=*/""), bytes_(bytes) {}
bool isMemoryMapped() const override { return true; }
char* readMemoryMapped(const int n) override {
JXL_ASSERT(pos_ + n <= bytes_.size());
char* const result =
const_cast<char*>(reinterpret_cast<const char*>(bytes_.data() + pos_));
pos_ += n;
return result;
}
bool read(char c[], const int n) override {
std::copy_n(readMemoryMapped(n), n, c);
return pos_ < bytes_.size();
}
ExrInt64 tellg() override { return pos_; }
void seekg(const ExrInt64 pos) override {
JXL_ASSERT(pos + 1 <= bytes_.size());
pos_ = pos;
}
private:
const Span<const uint8_t> bytes_;
size_t pos_ = 0;
};
} // namespace
Status DecodeImageEXR(Span<const uint8_t> bytes, const ColorHints& color_hints,
PackedPixelFile* ppf,
const SizeConstraints* constraints) {
InMemoryIStream is(bytes);
#ifdef __EXCEPTIONS
std::unique_ptr<OpenEXR::RgbaInputFile> input_ptr;
try {
input_ptr.reset(new OpenEXR::RgbaInputFile(is));
} catch (...) {
return JXL_FAILURE("OpenEXR failed to parse input");
}
OpenEXR::RgbaInputFile& input = *input_ptr;
#else
OpenEXR::RgbaInputFile input(is);
#endif
if ((input.channels() & OpenEXR::RgbaChannels::WRITE_RGB) !=
OpenEXR::RgbaChannels::WRITE_RGB) {
return JXL_FAILURE("only RGB OpenEXR files are supported");
}
const bool has_alpha = (input.channels() & OpenEXR::RgbaChannels::WRITE_A) ==
OpenEXR::RgbaChannels::WRITE_A;
const float intensity_target = OpenEXR::hasWhiteLuminance(input.header())
? OpenEXR::whiteLuminance(input.header())
: 0;
auto image_size = input.displayWindow().size();
// Size is computed as max - min, but both bounds are inclusive.
++image_size.x;
++image_size.y;
ppf->info.xsize = image_size.x;
ppf->info.ysize = image_size.y;
ppf->info.num_color_channels = 3;
const JxlDataType data_type =
kExrBitsPerSample == 16 ? JXL_TYPE_FLOAT16 : JXL_TYPE_FLOAT;
const JxlPixelFormat format{
/*num_channels=*/3u + (has_alpha ? 1u : 0u),
/*data_type=*/data_type,
/*endianness=*/JXL_NATIVE_ENDIAN,
/*align=*/0,
};
ppf->frames.clear();
// Allocates the frame buffer.
ppf->frames.emplace_back(image_size.x, image_size.y, format);
const auto& frame = ppf->frames.back();
const int row_size = input.dataWindow().size().x + 1;
// Number of rows to read at a time.
// https://www.openexr.com/documentation/ReadingAndWritingImageFiles.pdf
// recommends reading the whole file at once.
const int y_chunk_size = input.displayWindow().size().y + 1;
std::vector<OpenEXR::Rgba> input_rows(row_size * y_chunk_size);
for (int start_y =
std::max(input.dataWindow().min.y, input.displayWindow().min.y);
start_y <=
std::min(input.dataWindow().max.y, input.displayWindow().max.y);
start_y += y_chunk_size) {
// Inclusive.
const int end_y = std::min(
start_y + y_chunk_size - 1,
std::min(input.dataWindow().max.y, input.displayWindow().max.y));
input.setFrameBuffer(
input_rows.data() - input.dataWindow().min.x - start_y * row_size,
/*xStride=*/1, /*yStride=*/row_size);
input.readPixels(start_y, end_y);
for (int exr_y = start_y; exr_y <= end_y; ++exr_y) {
const int image_y = exr_y - input.displayWindow().min.y;
const OpenEXR::Rgba* const JXL_RESTRICT input_row =
&input_rows[(exr_y - start_y) * row_size];
uint8_t* row = static_cast<uint8_t*>(frame.color.pixels()) +
frame.color.stride * image_y;
const uint32_t pixel_size =
(3 + (has_alpha ? 1 : 0)) * kExrBitsPerSample / 8;
for (int exr_x =
std::max(input.dataWindow().min.x, input.displayWindow().min.x);
exr_x <=
std::min(input.dataWindow().max.x, input.displayWindow().max.x);
++exr_x) {
const int image_x = exr_x - input.displayWindow().min.x;
memcpy(row + image_x * pixel_size,
input_row + (exr_x - input.dataWindow().min.x), pixel_size);
}
}
}
ppf->color_encoding.transfer_function = JXL_TRANSFER_FUNCTION_LINEAR;
ppf->color_encoding.color_space = JXL_COLOR_SPACE_RGB;
ppf->color_encoding.primaries = JXL_PRIMARIES_SRGB;
ppf->color_encoding.white_point = JXL_WHITE_POINT_D65;
if (OpenEXR::hasChromaticities(input.header())) {
ppf->color_encoding.primaries = JXL_PRIMARIES_CUSTOM;
ppf->color_encoding.white_point = JXL_WHITE_POINT_CUSTOM;
const auto& chromaticities = OpenEXR::chromaticities(input.header());
ppf->color_encoding.primaries_red_xy[0] = chromaticities.red.x;
ppf->color_encoding.primaries_red_xy[1] = chromaticities.red.y;
ppf->color_encoding.primaries_green_xy[0] = chromaticities.green.x;
ppf->color_encoding.primaries_green_xy[1] = chromaticities.green.y;
ppf->color_encoding.primaries_blue_xy[0] = chromaticities.blue.x;
ppf->color_encoding.primaries_blue_xy[1] = chromaticities.blue.y;
ppf->color_encoding.white_point_xy[0] = chromaticities.white.x;
ppf->color_encoding.white_point_xy[1] = chromaticities.white.y;
}
// EXR uses binary16 or binary32 floating point format.
ppf->info.bits_per_sample = kExrBitsPerSample;
ppf->info.exponent_bits_per_sample = kExrBitsPerSample == 16 ? 5 : 8;
if (has_alpha) {
ppf->info.alpha_bits = kExrAlphaBits;
ppf->info.alpha_exponent_bits = ppf->info.exponent_bits_per_sample;
ppf->info.alpha_premultiplied = true;
}
ppf->info.intensity_target = intensity_target;
return true;
}
} // namespace extras
} // namespace jxl
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