Breaking: #97797 - GFX setting processor_path_lzw removed

See forge#97797

Description

The global configuration option $GLOBALS['TYPO3_CONF_VARS']['GFX']['processor_path_lzw'] was used to compress GIF and TIFF files with a different ImageMagick version, as LZW compression was removed from the distributed ImageMagick binaries back in 2004-2006.

Since then, both GIF and TIFF have had reduced impact on the web we know today.

For this reason, the value is removed. If GIF compression via LZW is wanted, it should be pointing to the main processor_path setting.

Impact

Compression via LZW for GIF files is now only applied when the corresponding ImageMagick version, found in processor_path is supporting LZW compression.

The GFX setting processor_path_lzw is not used anymore, and can safely be removed. When accessing the Install Tool, the setting is automatically removed from LocalConfiguration.php.

Affected installations

TYPO3 installations actively using GIF compression or GIF thumbnails over PNG thumbnails (if GFX/thumbnails_png is set to false), which might result in GIF files with a larger file size.

Migration

It is recommended to switch to PNG thumbnails (TYPO3 setting GFX/thumbnails_png), or use a ImageMagick version supporting LZW compression for GIF files, if this functionality is explicitly needed.

In addition, solutions such as gifsicle can be used instead to optimize GIF images.