This package is an improved version of golang.org/x/image/tiff. It uses a consolidated version of compress/lzw (hosted at: github.com/hhrutter/pdfcpu/lzw) for compression and also adds support for CMYK.
CCITT Group3/4 compression is supported for reading only.
As stated in this golang proposal right now Go lzw implementations are spread out over the standard library(compress/lzw) and golang.org/x/image/tiff/lzw. As of go1.11 compress/lzw works reliably for GIF only. This is also the reason the TIFF package at golang.org/x/image/tiff provides its own lzw implementation for compression.
In addition with PDF there is a third variant of lzw needed.
pdfcpu supports lzw compression for PDF files and hosts a consolidated implementation of lzw at github.com/hhrutter/pdfcpu/lzw which works for GIF, PDF and TIFF. It not only supports the PDF LZWFilter but also processing PDFs with embedded TIFF images. Therefore it also provides a variant of golang.org/x/image/tiff already leveraging the new consolidated lzw implementation(github.com/hhrutter/pdfcpu/lzw).
This implementation provides
- both lzw Reader and Writer as opposed to the original golang.org/x/image/tiff/lzw
- support for CMYK color models.
A compress/lzw that works for a maximum number of components with a specific need for lzw support (as of now GIF, TIFF and PDF) and as a side effect of this an improved TIFF package that may or may not will make it into standard library one day.