The renderer composited in 8-bit integers, so where a partly transparent
anti-aliased edge crossed opaque art (or a background colour) the result
came out at alpha 254 on some pixels, and PNG, TIFF and WebP files were
written with an alpha channel. Raster exports (and Save for Web) now
composite in floating point (vello_cpu's f32 pipeline, enabled as a
feature), offscreen groups, masks and patterns included; the canvas keeps
the faster 8-bit path.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>