Api changes between v2.2 and v2.3

Removed

• filter_factor removed from GDAL datasource options. This has always been available as a RasterSymbolizer property and can continue to be set there.

Changed

• colorize-alpha filter now takes a single color argument (rather than requiring more than one) and will use this single color to paint in place of the existing alpha values.
• Text label-position-tolerance is now a double rather than unsigned (https://github.com/mapnik/mapnik/commit/dcbbcdd8a92d4d27176998d9a90a4c836b5174e2)

Deprecated

• bilinear8 (raster scaling option) is not recommended for use and will be removed at Mapnik 3.x

Added

• webp image support. See Image-IO for more details
• scale-hsla image filter
• color-to-alpha image filter
• Map level background-image-opacity and background-image-comp-op: https://github.com/mapnik/mapnik/pull/1966
• offset support for LinePatternSymbolizer: https://github.com/mapnik/mapnik/pull/1991