fastimageresize

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

CHANGELOG

Supported pixel formats and available optimisations: - U8x4 - four u8 components per pixel: - 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 - U8 - one u8 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 - fastimageresize = "0.4" - glassbench = "0.3.0"

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 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 | 107.950 | 198.726 | 288.085 | 380.573 | | resize | 15.573 | 72.009 | 132.181 | 192.426 | | fir rust | 0.473 | 56.476 | 86.983 | 120.115 | | fir sse4.1 | - | 11.856 | 17.748 | 25.288 | | fir avx2 | - | 9.052 | 12.027 | 17.477 |

Resize RGBA image 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 | 107.165 | 191.338 | 281.272 | 372.183 | | resize | 18.099 | 79.512 | 149.128 | 225.173 | | fir rust | 13.265 | 69.358 | 99.794 | 132.545 | | fir sse4.1 | 11.739 | 23.080 | 29.013 | 36.556 | | fir avx2 | 6.958 | 15.590 | 18.610 | 24.219 |

Resize gray 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 | 96.792 | 143.195 | 188.121 | 240.504 | | resize | 10.582 | 26.577 | 53.537 | 81.599 | | fir rust | 0.203 | 24.832 | 30.962 | 46.958 |

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 wrapper that own 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); } } ```