//in safari, when canvas is captured, that has transparency, it fills transparent areas with 255 not black //we force transparent areas to be black instead static void PreProcessBitmap(RasterImage derivedImage) { using (RasterImage alpha = derivedImage.CreateAlphaImage()) { alpha.AddColorRgbRangeToRegion(new RasterColor(0, 0, 0), new RasterColor(3, 3, 3), RasterRegionCombineMode.Set); derivedImage.SetRegion(null, alpha.GetRegion(null), RasterRegionCombineMode.Set); FillCommand fill = new FillCommand(new RasterColor(0, 0, 0)); fill.Run(derivedImage); } }