fastimageresize

Rust library for fast image resizing with using of SIMD instructions.

Supported pixel formats and available optimisations: - U8 - one u8 component per pixel: - native Rust-code without forced SIMD - AVX2 - U8x3 - three u8 components per pixel (e.g. RGB): - native Rust-code without forced SIMD - SSE4.1 (auto-vectorization) - U8x4 - four u8 components per pixel (RGBA, RGBx, CMYK and other): - native Rust-code without forced SIMD - SSE4.1 - AVX2 - I32 - one i32 component per pixel: - native Rust-code without forced SIMD - F32 - one f32 component per pixel: - native Rust-code without forced SIMD

Benchmarks

Environment: - CPU: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz - RAM: DDR4 3000 MHz - Ubuntu 20.04 (linux 5.11) - Rust 1.56.1 - fastimageresize = "0.5" - glassbench = "0.3.0" - rustflags = ["-C", "llvm-args=-x86-branches-within-32B-boundaries"]

Other Rust libraries used to compare of resizing speed: - image = "0.23.14" (https://crates.io/crates/image) - resize = "0.7.2" (https://crates.io/crates/resize)

Resize algorithms: - Nearest - Convolution with Bilinear filter - Convolution with CatmullRom filter - Convolution with Lanczos3 filter

Resize RGB image (U8x3) 4928x3279 => 852x567

Pipeline:

src_image => resize => dst_image

Source image nasa-4928x3279.png
Numbers in table is mean duration of image resizing in milliseconds.

| | Nearest | Bilinear | CatmullRom | Lanczos3 | |------------|:-------:|:--------:|:----------:|:--------:| | image | 108.064 | 196.203 | 279.562 | 363.843 | | resize | 15.607 | 72.011 | 132.167 | 205.827 | | fir rust | 0.481 | 53.753 | 86.047 | 117.852 | | fir sse4.1 | - | 43.236 | 54.124 | 76.111 |

Resize RGBA image (U8x4) 4928x3279 => 852x567

Pipeline:

src_image => multiply by alpha => resize => divide by alpha => dst_image

Source image nasa-4928x3279.png
Numbers in table is mean duration of image resizing in milliseconds.

| | Nearest | Bilinear | CatmullRom | Lanczos3 | |------------|:-------:|:--------:|:----------:|:--------:| | image | 110.485 | 191.373 | 267.640 | 348.590 | | resize | 18.169 | 81.034 | 152.473 | 219.331 | | fir rust | 13.236 | 63.711 | 88.811 | 117.468 | | fir sse4.1 | 11.760 | 23.090 | 29.461 | 36.958 | | fir avx2 | 6.952 | 15.563 | 18.769 | 24.088 |

Resize grayscale image (U8) 4928x3279 => 852x567

Pipeline:

src_image => resize => dst_image

Source image nasa-4928x3279.png has converted into grayscale image with one byte per pixel.
Numbers in table is mean duration of image resizing in milliseconds.

| | Nearest | Bilinear | CatmullRom | Lanczos3 | |----------|:-------:|:--------:|:----------:|:--------:| | image | 94.548 | 140.978 | 178.725 | 218.875 | | resize | 9.884 | 26.831 | 54.274 | 82.708 | | fir rust | 0.196 | 22.045 | 24.734 | 35.630 | | fir avx2 | - | 9.623 | 7.869 | 11.832 |

Examples

Resize image

```rust use std::io::BufWriter; use std::num::NonZeroU32;

use image::codecs::png::PngEncoder; use image::io::Reader as ImageReader; use image::{ColorType, GenericImageView};

use fastimageresize as fr;

[test]

fn resizeimageexample() { // Read source image from file let img = ImageReader::open("./data/nasa-4928x3279.png") .unwrap() .decode() .unwrap(); let width = NonZeroU32::new(img.width()).unwrap(); let height = NonZeroU32::new(img.height()).unwrap(); let mut srcimage = fr::Image::fromvecu8( width, height, img.torgba8().into_raw(), fr::PixelType::U8x4, ) .unwrap();

// Create MulDiv instance
let alpha_mul_div: fr::MulDiv = Default::default();
// Multiple RGB channels of source image by alpha channel
alpha_mul_div
    .multiply_alpha_inplace(&mut src_image.view_mut())
    .unwrap();

// Create container for data of destination image
let dst_width = NonZeroU32::new(1024).unwrap();
let dst_height = NonZeroU32::new(768).unwrap();
let mut dst_image = fr::Image::new(dst_width, dst_height, src_image.pixel_type());

// Get mutable view of destination image data
let mut dst_view = dst_image.view_mut();

// Create Resizer instance and resize source image
// into buffer of destination image
let mut resizer = fr::Resizer::new(fr::ResizeAlg::Convolution(fr::FilterType::Lanczos3));
resizer.resize(&src_image.view(), &mut dst_view).unwrap();

// Divide RGB channels of destination image by alpha
alpha_mul_div.divide_alpha_inplace(&mut dst_view).unwrap();

// Write destination image as PNG-file
let mut result_buf = BufWriter::new(Vec::new());
PngEncoder::new(&mut result_buf)
    .encode(
        dst_image.buffer(),
        dst_width.get(),
        dst_height.get(),
        ColorType::Rgba8,
    )
    .unwrap();

} ```

Change CPU extensions used by resizer

```rust use fastimageresize as fr;

fn main() { let mut resizer = fr::Resizer::new(fr::ResizeAlg::Convolution(fr::FilterType::Lanczos3)); unsafe { resizer.setcpuextensions(fr::CpuExtensions::Sse4_1); } } ```