lzw

Documentation

Overview

Package lzw implements the Lempel-Ziv-Welch compressed data format, described in T. A. Welch, “A Technique for High-Performance Data Compression”, Computer, 17(6) (June 1984), pp 8-19.

In particular, it implements LZW as used by the TIFF file format, including an "off by one" algorithmic difference when compared to standard LZW.

Index

• func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser
• type Order

Functions

func NewReader

func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser

NewReader creates a new io.ReadCloser. Reads from the returned io.ReadCloser read and decompress data from r. If r does not also implement io.ByteReader, the decompressor may read more data than necessary from r. It is the caller's responsibility to call Close on the ReadCloser when finished reading. The number of bits to use for literal codes, litWidth, must be in the range [2,8] and is typically 8. It must equal the litWidth used during compression.

Types

type Order

type Order int

Order specifies the bit ordering in an LZW data stream.

const (
	// LSB means Least Significant Bits first, as used in the GIF file format.
	LSB Order = iota
	// MSB means Most Significant Bits first, as used in the TIFF and PDF
	// file formats.
	MSB
)