diff options
Diffstat (limited to 'vendor/exr/src/compression/pxr24.rs')
| -rw-r--r-- | vendor/exr/src/compression/pxr24.rs | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/vendor/exr/src/compression/pxr24.rs b/vendor/exr/src/compression/pxr24.rs new file mode 100644 index 0000000..9461c6a --- /dev/null +++ b/vendor/exr/src/compression/pxr24.rs @@ -0,0 +1,261 @@ + +//! Lossy compression for F32 data, but lossless compression for U32 and F16 data. +// see https://github.com/AcademySoftwareFoundation/openexr/blob/master/OpenEXR/IlmImf/ImfPxr24Compressor.cpp + +// This compressor is based on source code that was contributed to +// OpenEXR by Pixar Animation Studios. The compression method was +// developed by Loren Carpenter. + + +// The compressor preprocesses the pixel data to reduce entropy, and then calls zlib. +// Compression of HALF and UINT channels is lossless, but compressing +// FLOAT channels is lossy: 32-bit floating-point numbers are converted +// to 24 bits by rounding the significand to 15 bits. +// +// When the compressor is invoked, the caller has already arranged +// the pixel data so that the values for each channel appear in a +// contiguous block of memory. The compressor converts the pixel +// values to unsigned integers: For UINT, this is a no-op. HALF +// values are simply re-interpreted as 16-bit integers. FLOAT +// values are converted to 24 bits, and the resulting bit patterns +// are interpreted as integers. The compressor then replaces each +// value with the difference between the value and its left neighbor. +// This turns flat fields in the image into zeroes, and ramps into +// strings of similar values. Next, each difference is split into +// 2, 3 or 4 bytes, and the bytes are transposed so that all the +// most significant bytes end up in a contiguous block, followed +// by the second most significant bytes, and so on. The resulting +// string of bytes is compressed with zlib. + +use super::*; + +use crate::error::Result; +use lebe::io::ReadPrimitive; + + +// scanline decompression routine, see https://github.com/openexr/openexr/blob/master/OpenEXR/IlmImf/ImfScanLineInputFile.cpp +// 1. Uncompress the data, if necessary (If the line is uncompressed, it's in XDR format, regardless of the compressor's output format.) +// 3. Convert one scan line's worth of pixel data back from the machine-independent representation +// 4. Fill the frame buffer with pixel data, respective to sampling and whatnot + + +#[cfg_attr(target_endian = "big", allow(unused, unreachable_code))] +pub fn compress(channels: &ChannelList, remaining_bytes: ByteVec, area: IntegerBounds) -> Result<ByteVec> { + #[cfg(target_endian = "big")] { + return Err(Error::unsupported( + "PXR24 compression method not supported yet on big endian processor architecture" + )) + } + + if remaining_bytes.is_empty() { return Ok(Vec::new()); } + + // see https://github.com/AcademySoftwareFoundation/openexr/blob/3bd93f85bcb74c77255f28cdbb913fdbfbb39dfe/OpenEXR/IlmImf/ImfTiledOutputFile.cpp#L750-L842 + let remaining_bytes = super::convert_current_to_little_endian(remaining_bytes, channels, area); + let mut remaining_bytes = remaining_bytes.as_slice(); // TODO less allocation + + let bytes_per_pixel: usize = channels.list.iter() + .map(|channel| match channel.sample_type { + SampleType::F16 => 2, SampleType::F32 => 3, SampleType::U32 => 4, + }) + .sum(); + + let mut raw = vec![0_u8; bytes_per_pixel * area.size.area()]; + + { + let mut write = raw.as_mut_slice(); + + // TODO this loop should be an iterator in the `IntegerBounds` class, as it is used in all compressio methods + for y in area.position.1..area.end().1 { + for channel in &channels.list { + if mod_p(y, usize_to_i32(channel.sampling.1)) != 0 { continue; } + + // this apparently can't be a closure in Rust 1.43 due to borrowing ambiguity + let sample_count_x = channel.subsampled_resolution(area.size).0; + macro_rules! split_off_write_slice { () => {{ + let (slice, rest) = write.split_at_mut(sample_count_x); + write = rest; + slice + }}; } + + let mut previous_pixel: u32 = 0; + + match channel.sample_type { + SampleType::F16 => { + let out_byte_tuples = split_off_write_slice!().iter_mut() + .zip(split_off_write_slice!()); + + for (out_byte_0, out_byte_1) in out_byte_tuples { + let pixel = u16::read_from_native_endian(&mut remaining_bytes).unwrap() as u32; + let [byte_1, byte_0] = (pixel.wrapping_sub(previous_pixel) as u16).to_ne_bytes(); + + *out_byte_0 = byte_0; + *out_byte_1 = byte_1; + previous_pixel = pixel; + } + }, + + SampleType::U32 => { + let out_byte_quadruplets = split_off_write_slice!().iter_mut() + .zip(split_off_write_slice!()) + .zip(split_off_write_slice!()) + .zip(split_off_write_slice!()); + + for (((out_byte_0, out_byte_1), out_byte_2), out_byte_3) in out_byte_quadruplets { + let pixel = u32::read_from_native_endian(&mut remaining_bytes).unwrap(); + let [byte_3, byte_2, byte_1, byte_0] = pixel.wrapping_sub(previous_pixel).to_ne_bytes(); + + *out_byte_0 = byte_0; + *out_byte_1 = byte_1; + *out_byte_2 = byte_2; + *out_byte_3 = byte_3; + previous_pixel = pixel; + } + }, + + SampleType::F32 => { + let out_byte_triplets = split_off_write_slice!().iter_mut() + .zip(split_off_write_slice!()) + .zip(split_off_write_slice!()); + + for ((out_byte_0, out_byte_1), out_byte_2) in out_byte_triplets { + let pixel = f32_to_f24(f32::read_from_native_endian(&mut remaining_bytes).unwrap()); + let [byte_2, byte_1, byte_0, _] = pixel.wrapping_sub(previous_pixel).to_ne_bytes(); + previous_pixel = pixel; + + *out_byte_0 = byte_0; + *out_byte_1 = byte_1; + *out_byte_2 = byte_2; + } + }, + } + } + } + + debug_assert_eq!(write.len(), 0, "bytes left after compression"); + } + + Ok(miniz_oxide::deflate::compress_to_vec_zlib(raw.as_slice(), 4)) +} + +#[cfg_attr(target_endian = "big", allow(unused, unreachable_code))] +pub fn decompress(channels: &ChannelList, bytes: ByteVec, area: IntegerBounds, expected_byte_size: usize, pedantic: bool) -> Result<ByteVec> { + #[cfg(target_endian = "big")] { + return Err(Error::unsupported( + "PXR24 decompression method not supported yet on big endian processor architecture" + )) + } + + let options = zune_inflate::DeflateOptions::default().set_limit(expected_byte_size).set_size_hint(expected_byte_size); + let mut decoder = zune_inflate::DeflateDecoder::new_with_options(&bytes, options); + let raw = decoder.decode_zlib() + .map_err(|_| Error::invalid("zlib-compressed data malformed"))?; // TODO share code with zip? + + let mut read = raw.as_slice(); + let mut out = Vec::with_capacity(expected_byte_size.min(2048*4)); + + for y in area.position.1 .. area.end().1 { + for channel in &channels.list { + if mod_p(y, usize_to_i32(channel.sampling.1)) != 0 { continue; } + + let sample_count_x = channel.subsampled_resolution(area.size).0; + let mut read_sample_line = ||{ + if sample_count_x > read.len() { return Err(Error::invalid("not enough data")) } + let (samples, rest) = read.split_at(sample_count_x); + read = rest; + Ok(samples) + }; + + let mut pixel_accumulation: u32 = 0; + + match channel.sample_type { + SampleType::F16 => { + let sample_byte_pairs = read_sample_line()?.iter() + .zip(read_sample_line()?); + + for (&in_byte_0, &in_byte_1) in sample_byte_pairs { + let difference = u16::from_ne_bytes([in_byte_1, in_byte_0]) as u32; + pixel_accumulation = pixel_accumulation.overflowing_add(difference).0; + out.extend_from_slice(&(pixel_accumulation as u16).to_ne_bytes()); + } + }, + + SampleType::U32 => { + let sample_byte_quads = read_sample_line()?.iter() + .zip(read_sample_line()?) + .zip(read_sample_line()?) + .zip(read_sample_line()?); + + for (((&in_byte_0, &in_byte_1), &in_byte_2), &in_byte_3) in sample_byte_quads { + let difference = u32::from_ne_bytes([in_byte_3, in_byte_2, in_byte_1, in_byte_0]); + pixel_accumulation = pixel_accumulation.overflowing_add(difference).0; + out.extend_from_slice(&pixel_accumulation.to_ne_bytes()); + } + }, + + SampleType::F32 => { + let sample_byte_triplets = read_sample_line()?.iter() + .zip(read_sample_line()?).zip(read_sample_line()?); + + for ((&in_byte_0, &in_byte_1), &in_byte_2) in sample_byte_triplets { + let difference = u32::from_ne_bytes([0, in_byte_2, in_byte_1, in_byte_0]); + pixel_accumulation = pixel_accumulation.overflowing_add(difference).0; + out.extend_from_slice(&pixel_accumulation.to_ne_bytes()); + } + } + } + } + } + + if pedantic && !read.is_empty() { + return Err(Error::invalid("too much data")); + } + + Ok(super::convert_little_endian_to_current(out, channels, area)) +} + + + + +/// Conversion from 32-bit to 24-bit floating-point numbers. +/// Reverse conversion is just a simple 8-bit left shift. +pub fn f32_to_f24(float: f32) -> u32 { + let bits = float.to_bits(); + + let sign = bits & 0x80000000; + let exponent = bits & 0x7f800000; + let mantissa = bits & 0x007fffff; + + let result = if exponent == 0x7f800000 { + if mantissa != 0 { + // F is a NAN; we preserve the sign bit and + // the 15 leftmost bits of the significand, + // with one exception: If the 15 leftmost + // bits are all zero, the NAN would turn + // into an infinity, so we have to set at + // least one bit in the significand. + + let mantissa = mantissa >> 8; + (exponent >> 8) | mantissa | if mantissa == 0 { 1 } else { 0 } + } + else { // F is an infinity. + exponent >> 8 + } + } + else { // F is finite, round the significand to 15 bits. + let result = ((exponent | mantissa) + (mantissa & 0x00000080)) >> 8; + + if result >= 0x7f8000 { + // F was close to FLT_MAX, and the significand was + // rounded up, resulting in an exponent overflow. + // Avoid the overflow by truncating the significand + // instead of rounding it. + + (exponent | mantissa) >> 8 + } + else { + result + } + }; + + return (sign >> 8) | result; +}
\ No newline at end of file |