Struct CompressionOptions 

pub struct CompressionOptions { /* private fields */ }

Everything about how an image is to be compressed.

use fits_io::image::compression::{Compression, CompressionOptions, Quantize};

// Rice coding, in tiles of 100 by 100 pixels.
let options = CompressionOptions::new(Compression::Rice).with_tile_size(&[100, 100]);

// A floating point image, quantised to a quarter of its own noise.
let lossy = CompressionOptions::new(Compression::Rice)
    .with_quantization(Quantize::NoiseLevel(4.0));

// HCOMPRESS, throwing away the low bits of the transform's coefficients.
let smooth = CompressionOptions::new(Compression::Hcompress { scale: 16 });

Implementations

impl CompressionOptions

pub fn new(compression: Compression) -> Self

Compress with compression, in the convention’s default tiles — one row of the image each — and without quantising.

pub fn with_tile_size(self, tile: &[u32]) -> Self

Cut the image into tiles of this shape, fastest axis first.

A shape shorter than the image’s axes has the remaining axes tiled one plane at a time. Bigger tiles compress a little better and cost more to read a small part of the image from.

pub fn with_quantization(self, quantize: Quantize) -> Self

Quantise a floating point image before compressing it.

This has no effect on an image that is already integers.

pub fn with_dithering(self, quantization: Quantization) -> Self

Which dithering the quantisation uses.

Quantization::SubtractiveDither1 unless this says otherwise, which is what a floating point image usually wants.

pub fn with_dither_seed(self, seed: i64) -> Self

Where in the dithering sequence the first tile starts, from 1 to 10000.

Two files written from the same data with the same seed come out identical, which is what makes a compressed file reproducible.

pub fn with_block_size(self, block: usize) -> Self

How many values Rice coding fits its split point to at a time.

Thirty-two unless this says otherwise, which is what the convention’s reference implementation uses.

pub fn compression(&self) -> Compression

The algorithm the tiles are compressed with.

Trait Implementations

impl Clone for CompressionOptions

fn clone(&self) -> CompressionOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CompressionOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CompressionOptions

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for CompressionOptions

fn eq(&self, other: &CompressionOptions) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for CompressionOptions