43 lines
1.2 KiB
Rust
43 lines
1.2 KiB
Rust
extern crate image;
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use image::{Pixel, GenericImage, ImageResult};
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/// Compute a PSNR between two images.
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///
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/// Will panic an error if the two images don't have the same size.
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pub fn psnr<P: Pixel<Subpixel=u8>, T: GenericImage<Pixel=P>>(img1: &T, img2: &T) -> f64 {
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let twenty_log10_max: f64 = 20.0 * (std::u8::MAX as f64).log10();
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assert_eq!(img1.dimensions(), img2.dimensions());
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let mut mse = 0.0;
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for x in 0 .. img1.dimensions().0 {
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for y in 0 .. img1.dimensions().1 {
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let p1 = img1.get_pixel(x, y).to_rgba();
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let p2 = img2.get_pixel(x, y).to_rgba();
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let dx = p1.data[0] as f64 - p2.data[0] as f64;
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let dy = p1.data[1] as f64 - p2.data[1] as f64;
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let dz = p1.data[2] as f64 - p2.data[2] as f64;
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let dx = dx * dx;
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let dy = dy * dy;
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let dz = dz * dz;
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mse += dx + dy + dz;
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}
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}
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mse /= (img1.dimensions().0 * img1.dimensions().1 * 3) as f64;
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twenty_log10_max - 10.0 * mse.log10()
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}
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pub fn psnr_files(path1: &str, path2: &str) -> ImageResult<f64> {
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let img1 = image::open(path1)?;
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let img2 = image::open(path2)?;
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Ok(psnr(&img1, &img2))
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}
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