75 lines
2.7 KiB
Rust
75 lines
2.7 KiB
Rust
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extern crate image as png;
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use std::cmp::Ordering;
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extern crate exr;
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/// Extract all exr pixel information into pngs.
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/// Writes each channel of each mip map of each layer as one grayscale png.
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/// May appear black for single-color images.
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pub fn main() {
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use exr::prelude::*;
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let path = "mip_maps.exr";
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let start_time = ::std::time::Instant::now();
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// load the exr file from disk with multi-core decompression
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let image = read_all_data_from_file(path)
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.expect("run example `5c_write_mip_maps` to generate this image file");
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// warning: highly unscientific benchmarks ahead!
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println!("\nloaded file in {:?}s", start_time.elapsed().as_secs_f32());
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let _ = std::fs::create_dir_all("pngs/");
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println!("writing images...");
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for (layer_index, layer) in image.layer_data.iter().enumerate() {
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let layer_name = layer.attributes.layer_name.as_ref()
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.map_or(String::from("1"), Text::to_string);
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for channel in &layer.channel_data.list {
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for (level, level_size) in layer.levels_with_resolution(&channel.sample_data) {
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let data : Vec<f32> = level.values_as_f32().collect();
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save_f32_image_as_png(&data, level_size, format!(
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"pngs/{} ({}) {}.{}x{}.png",
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layer_index, layer_name, channel.name,
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level_size.width(), level_size.height(),
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))
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}
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}
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}
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/// Save raw float data to a PNG file, doing automatic brightness adjustments per channel
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fn save_f32_image_as_png(data: &[f32], size: Vec2<usize>, name: String) {
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let mut png_buffer = png::GrayImage::new(size.width() as u32, size.height() as u32);
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let mut sorted = Vec::from(data);
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sorted.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Less));
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// percentile normalization
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let max = sorted[7 * sorted.len() / 8];
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let min = sorted[1 * sorted.len() / 8];
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// primitive tone mapping
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let tone = |v: f32| (v - 0.5).tanh() * 0.5 + 0.5;
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let max_toned = tone(*sorted.last().unwrap());
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let min_toned = tone(*sorted.first().unwrap());
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// for each pixel, tone map the value
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for (x, y, pixel) in png_buffer.enumerate_pixels_mut() {
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let v = data[y as usize * size.0 + x as usize];
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let v = (v - min) / (max - min);
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let v = tone(v);
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let v = (v - min_toned) / (max_toned - min_toned);
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// TODO does the `image` crate expect gamma corrected data?
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*pixel = png::Luma([(v.max(0.0).min(1.0) * 255.0) as u8]);
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}
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png_buffer.save(&name).unwrap();
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}
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println!("extracted all layers to folder `./pngs/*.png`");
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}
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