Struct JxlDecoder

pub struct JxlDecoder<R> { /* private fields */ }

Available on crate feature image only.

JPEG XL decoder which implements ImageDecoder.

Supported features

Currently JxlDecoder supports following features:

• Returning images of 8-bit, 16-bit integer and 32-bit float samples
• RGB or luma-only images, with or without alpha
• Returning ICC profiles via icc_profile
• Setting decoder limits (caveat: memory limits are not strict)
• Cropped decoding with ImageDecoderRect
• (When lcms2 feature is enabled) Converting CMYK images to sRGB color space

Some features are planned but not implemented yet:

• Decoding animations

Note about color management

JxlDecoder doesn’t do color management by itself (except for CMYK images, which will be converted to sRGB color space if lcms2 is available). Consumers should apply appropriate color transforms using ICC profile returned by icc_profile(), otherwise colors may be inaccurate.

Examples

Converting JPEG XL image to PNG:

use image::{DynamicImage, ImageDecoder};
use jxl_oxide::integration::JxlDecoder;

// Read and decode a JPEG XL image.
let file = std::fs::File::open("image.jxl")?;
let mut decoder = JxlDecoder::new(file)?;
let icc = decoder.icc_profile()?;
let mut image = DynamicImage::from_decoder(decoder)?;

// Perform color transform using the ICC profile.
// Note that ICC profile will be always available for images decoded by `JxlDecoder`.
if let Some(icc) = icc {
    do_color_transform(&mut image, icc)?;
}

// Save decoded image to PNG.
image.save("image.png")?;

Implementations

impl<R: Read> JxlDecoder<R>

pub fn new(reader: R) -> ImageResult<Self>

Initializes a decoder which reads from given image stream.

Decoder will be initialized with default thread pool.

pub fn with_thread_pool(reader: R, pool: JxlThreadPool) -> ImageResult<Self>

Initializes a decoder which reads from given image stream, with custom thread pool.

Trait Implementations

impl<R: Read> ImageDecoder for JxlDecoder<R>

fn dimensions(&self) -> (u32, u32)

Returns a tuple containing the width and height of the image

fn color_type(&self) -> ColorType

Returns the color type of the image data produced by this decoder

fn read_image(self, buf: &mut [u8]) -> ImageResult<()>

where Self: Sized,

Returns all the bytes in the image.

fn read_image_boxed(self: Box<Self>, buf: &mut [u8]) -> ImageResult<()>

Use read_image instead; this method is an implementation detail needed so the trait can be object safe.

fn icc_profile(&mut self) -> ImageResult<Option<Vec<u8>>>

Returns the ICC color profile embedded in the image, or Ok(None) if the image does not have one.

fn set_limits(&mut self, limits: Limits) -> ImageResult<()>

Set the decoder to have the specified limits. See Limits for the different kinds of limits that is possible to set.

fn original_color_type(&self) -> ExtendedColorType

Returns the color type of the image file before decoding

fn exif_metadata(&mut self) -> Result<Option<Vec<u8>>, ImageError>

Returns the raw Exif chunk, if it is present. A third-party crate such as kamadak-exif is required to actually parse it.

fn orientation(&mut self) -> Result<Orientation, ImageError>

Returns the orientation of the image.

fn total_bytes(&self) -> u64

Returns the total number of bytes in the decoded image.

impl<R: Read> ImageDecoderRect for JxlDecoder<R>

fn read_rect( &mut self, x: u32, y: u32, width: u32, height: u32, buf: &mut [u8], row_pitch: usize, ) -> ImageResult<()>

Decode a rectangular section of the image.