[agg][alpha_channel]Anti-Grain Geometry - Version 2.2 Release Notes : pre-multiplied result on the canvas. It has even less number of calculations than agg::pixfmt_rgba32_pre. Format agg::pixfmt_rgba32_plain is slow because of division operations. APIs allowing for alpha-blending require premultiplied colors.
[agg][alpha_channel]Anti-Grain Geometry - Version 2.2 Release Notes : pre-multiplied result on the canvas. It has even less number of calculations than agg::pixfmt_rgba32_pre. Format agg::pixfmt_rgba32_plain is slow because of division operations. APIs allowing for alpha-blending require premultiplied colors.