# Image [](https://crates.io/crates/image) [](https://travis-ci.org/image-rs/image) [](https://gitter.im/image-rs/image?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
Maintainers: @HeroicKatora, @fintelia
[How to contribute](https://github.com/image-rs/organization/blob/master/CONTRIBUTING.md)
## An Image Processing Library
This crate provides basic imaging processing functions and methods for converting to and from image formats.
All image processing functions provided operate on types that implement the ```GenericImage``` trait and return an ```ImageBuffer```.
## 1. Documentation
https://docs.rs/image
## 2. Supported Image Formats
```image``` provides implementations of common image format encoders and decoders.
### 2.1 Supported Image Formats
| PNG | All supported color types | Same as decoding|
| JPEG | Baseline and progressive | Baseline JPEG |
| GIF | Yes | Yes |
| BMP | Yes | RGB(8), RGBA(8), Gray(8), GrayA(8) |
| ICO | Yes | Yes |
| TIFF | Baseline(no fax support) + LZW + PackBits | RGB(8), RGBA(8), Gray(8) |
| WebP | Lossy(Luma channel only) | No |
| PNM | PBM, PGM, PPM, standard PAM | Yes |
### 2.2 The ```ImageDecoder``` Trait
All image format decoders implement the ```ImageDecoder``` trait which provides the following methods:
+ **dimensions**: Return a tuple containing the width and height of the image
+ **colortype**: Return the color type of the image.
+ **row_len**: Returns the length in bytes of one decoded row of the image
+ **read_scanline**: Read one row from the image into buf Returns the row index
+ **read_image**: Decode the entire image and return it as a Vector
+ **load_rect**: Decode a specific region of the image
## 3 Pixels
```image``` provides the following pixel types:
+ **Rgb**: RGB pixel
+ **Rgba**: RGBA pixel
+ **Luma**: Grayscale pixel
+ **LumaA**: Grayscale with alpha
All pixels are parameterised by their component type.
## 4 Images
### 4.1 The ```GenericImage``` Trait
A trait that provides functions for manipulating images, parameterised over the image's pixel type.
```rust
# use image::{Pixel, Pixels};
pub trait GenericImage {
/// The pixel type.
type Pixel: Pixel;
/// The width and height of this image.
fn dimensions(&self) -> (u32, u32);
/// The bounding rectangle of this image.
fn bounds(&self) -> (u32, u32, u32, u32);
/// Return the pixel located at (x, y)
fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel;
/// Put a pixel at location (x, y)
fn put_pixel(&mut self, x: u32, y: u32, pixel: Self::Pixel);
/// Return an Iterator over the pixels of this image.
/// The iterator yields the coordinates of each pixel
/// along with their value
fn pixels(&self) -> Pixels<Self>;
}
```
### 4.2 Representation of Images
```image``` provides two main ways of representing image data:
#### 4.2.1 ```ImageBuffer```
An image parameterised by its Pixel types, represented by a width and height and a vector of pixels. It provides direct access to its pixels and implements the ```GenericImage``` trait.
```rust
extern crate image;
use image::{GenericImage, GenericImageView, ImageBuffer, RgbImage};
// Construct a new RGB ImageBuffer with the specified width and height.
let img: RgbImage = ImageBuffer::new(512, 512);
// Construct a new by repeated calls to the supplied closure.
let mut img = ImageBuffer::from_fn(512, 512, |x, y| {
if x % 2 == 0 {
image::Luma([0u8])
} else {
image::Luma([255u8])
}
});
// Obtain the image's width and height.
let (width, height) = img.dimensions();
// Access the pixel at coordinate (100, 100).
let pixel = img[(100, 100)];
// Or use the ```get_pixel``` method from the ```GenericImage``` trait.
let pixel = *img.get_pixel(100, 100);
// Put a pixel at coordinate (100, 100).
img.put_pixel(100, 100, pixel);
// Iterate over all pixels in the image.
for pixel in img.pixels() {
// Do something with pixel.
}
```
#### 4.2.2 ```DynamicImage```
A ```DynamicImage``` is an enumeration over all supported ```ImageBuffer<P>``` types.
Its exact image type is determined at runtime. It is the type returned when opening an image.
For convenience ```DynamicImage```'s reimplement all image processing functions.
```DynamicImage``` implement the ```GenericImage``` trait for RGBA pixels.
#### 4.2.3 ```SubImage```
A view into another image, delimited by the coordinates of a rectangle.
This is used to perform image processing functions on a subregion of an image.
```rust
extern crate image;
use image::{GenericImageView, ImageBuffer, RgbImage, imageops};
let mut img: RgbImage = ImageBuffer::new(512, 512);
let subimg = imageops::crop(&mut img, 0, 0, 100, 100);
assert!(subimg.dimensions() == (100, 100));
```
## 5 Image Processing Functions
These are the functions defined in the ```imageops``` module. All functions operate on types that implement the ```GenericImage``` trait.
+ **blur**: Performs a Gaussian blur on the supplied image.
+ **brighten**: Brighten the supplied image
+ **huerotate**: Hue rotate the supplied image by degrees
+ **contrast**: Adjust the contrast of the supplied image
+ **crop**: Return a mutable view into an image
+ **filter3x3**: Perform a 3x3 box filter on the supplied image.
+ **flip_horizontal**: Flip an image horizontally
+ **flip_vertical**: Flip an image vertically
+ **grayscale**: Convert the supplied image to grayscale
+ **invert**: Invert each pixel within the supplied image This function operates in place.
+ **resize**: Resize the supplied image to the specified dimensions
+ **rotate180**: Rotate an image 180 degrees clockwise.
+ **rotate270**: Rotate an image 270 degrees clockwise.
+ **rotate90**: Rotate an image 90 degrees clockwise.
+ **unsharpen**: Performs an unsharpen mask on the supplied image
## 6 Examples
### 6.1 Opening And Saving Images
```image``` provides the ```open``` function for opening images from a path.
The image format is determined from the path's file extension.
```rust,no_run
extern crate image;
use image::GenericImageView;
fn main() {
// Use the open function to load an image from a Path.
// ```open``` returns a `DynamicImage` on success.
let img = image::open("tests/images/jpg/progressive/cat.jpg").unwrap();
// The dimensions method returns the images width and height.
println!("dimensions {:?}", img.dimensions());
// The color method returns the image's `ColorType`.
println!("{:?}", img.color());
// Write the contents of this image to the Writer in PNG format.
img.save("test.png").unwrap();
}
```
### 6.2 Generating Fractals
```rust,no_run
//! An example of generating julia fractals.
extern crate image;
extern crate num_complex;
fn main() {
let imgx = 800;
let imgy = 800;
let scalex = 3.0 / imgx as f32;
let scaley = 3.0 / imgy as f32;
// Create a new ImgBuf with width: imgx and height: imgy
let mut imgbuf = image::ImageBuffer::new(imgx, imgy);
// Iterate over the coordinates and pixels of the image
for (x, y, pixel) in imgbuf.enumerate_pixels_mut() {
let r = (0.3 * x as f32) as u8;
let b = (0.3 * y as f32) as u8;
*pixel = image::Rgb([r, 0, b]);
}
// A redundant loop to demonstrate reading image data
for x in 0..imgx {
for y in 0..imgy {
let cx = y as f32 * scalex - 1.5;
let cy = x as f32 * scaley - 1.5;
let c = num_complex::Complex::new(-0.4, 0.6);
let mut z = num_complex::Complex::new(cx, cy);
let mut i = 0;
while i < 255 && z.norm() <= 2.0 {
z = z * z + c;
i += 1;
}
let pixel = imgbuf.get_pixel_mut(x, y);
let image::Rgb(data) = *pixel;
*pixel = image::Rgb([data[0], i as u8, data[2]]);
}
}
// Save the image as “fractal.png”, the format is deduced from the path
imgbuf.save("fractal.png").unwrap();
}
```
Example output:
<img src="examples/fractal.png" alt="A Julia Fractal, c: -0.4 + 0.6i" width="500" />
### 6.3 Writing raw buffers
If the high level interface is not needed because the image was obtained by other means, `image` provides the function `save_buffer` to save a buffer to a file.
```rust,no_run
extern crate image;
fn main() {
let buffer: &[u8] = unimplemented!(); // Generate the image data
// Save the buffer as "image.png"
image::save_buffer("image.png", buffer, 800, 600, image::RGB(8)).unwrap()
}
```