With c469a63, the new work on core compositing replaced the older initial implementation of compositing for rasters-only. This change should behave very similarly, but a few of the mode names previously supported are now removed:
All current supported compositing modes are at https://github.com/mapnik/mapnik/blob/master/include/mapnik/image_compositing.hpp#L40-70
We need to discuss with Marcin if dropping these is okay, or if there is a good reason to support them.
We are using grain_merge mode on the map with hillshade: http://kosmosnimki.ru/permalink.html?Nfbc1062b
grain-merge added back (by implementing with agg) in 6bea57d. and also grain-extract added in f3c774b
remove now unused blending modes as they have been replaced with AGG …
…compositing modes - refs #1206
finished with 7621124, closing.
finish full back comptibility for raster-mode - refs #1206 and #1432