TIFF compression not working?

[muccigrosso]

Is there a problem with tiff group4 and fax compression? I'm having trouble getting good compression with them, and perhaps coincidentally these are the two compression schemes that were affected by this patch. For example,

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magick logo: -threshold 80% -alpha off -monochrome -compress METHOD -quality 100 output.tiff

gives me a 7k file when I use LZW as the method, but 39k for both fax and group4 (and for pbm), and some larger files I'm using aren't showing good compression with group4 and those other parameters. When I do `identify -verbose` the fax and group4 versions yield:

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Compression: None

whereas some files I did a few weeks ago show the expected compression value.

On a Mac, ImageMagick 7.0.8-11 Q16 x86_64 2018-09-01, --with-fftw --with-x11 --with-openjpeg.

[fmw42]

I can confirm that there has been a change between 6.9.10.10 and 6.9.10.11 and also between 7.0.8.10 and 7.0.8.11 Mac OSX Sierra

In the latest versions, this command

magick logo: -threshold 80% -alpha off -monochrome -compress fax -type bilevel output.tiff

using magick identify -verbose

shows

compression=none

Same for -compress group4


This looks like a bug to me.

[dlemstra]

The fix for this will be available in the next release: https://github.com/ImageMagick/ImageMagick/issues/1297

[muccigrosso]

This seems to be all fixed in IM 7.0.8-12.