Support for CCITT group 4 compression in UTIF.encodeImage

[sujithj-git]

The UTIF.encodeImage method currently encodes TIFFs without any compression, leading to significantly larger output file sizes.

The library's documentation mentions support for Fax 4 (CCITT Group 4) compression. My goal is to encode a TIFF with CCITT Group 4 compression from image data (e.g., a PNG).

Could someone provide an example or guidance on how to correctly use UTIF.encodeImage to apply CCITT Group 4 compression? Specifically, how should the metadata and data be structured for this to work?

[photopea]

Currently, UTIF.js uses DEFLATE (GZIP) compression for encoding, if the "pako" library is available, see

UTIF.js/UTIF.js

Line 43 in 2e6be65

var cmpr = (window && window.pako) ? 8 : 1;

I have a TIFF file of 18 kB with CCITT compression (1728 x 2376 pixels), when encoding it with UTIF.js (DEFLATE with PAKO), it becomes 66 kB. If there was no compression, it would be 1 bit per pixel (513 kB).

Are you aware that CCITT supports only black-and-white pixels? There are no colors and no shades of gray.