On 2007-June-13 , at 09:35 , Niko Kiirala wrote:
Tue, 12 Jun 2007 23:44:06 +0200 jiho <jo.irisson@...400...> kirjoitti:
Quartz (the equivalent of Cairo on Mac OS X) produces pdfs with drop- shadows that look quite like vector effects rather than raster blurs to me. These are two examples produced from an Export to PDF (1) and Print to PDF (2): http://jo.irisson.free.fr/dropbox/inkscape/quartz_pdf_1.pdf http://jo.irisson.free.fr/dropbox/inkscape/quartz_pdf_2_print.pdf I already looked at PDFs produced by quartz on other platforms and the blur was still there. Maybe that could be a lead in the right direction.
Seems like a raster blur to me, with a quite low resolution too.
It looks like most pdf viewers apply bilinear or better filtering when enlarging images. With blur, this filtering is not apparent. If you look at those round edges in letters (especially o) you can notice, they're slightly jagged. Or if you try those with kpdf, which seems to use nearest neighbour filtering, the raster blocks are quite obvious.
Actually, this is the same thing Inkscape does when rendering blur with anything but the best quality: blur a smaller version of the image and then enlarge it to original size with bilinear filtering. It seems quite correct, too.
Indeed, sorry to have leaded you in the wrong way. I opened the pdf in Adobe Reader and zooming on the letters shows the raster nature of the blur pretty obviously. Previously I only checked in Adobe Reader that the blur was there and used only Preview (the PDF viewer of OS X) to zoom in. It seems Preview is optimized for this kind of blur since the pixels are much less visible with it that with Adobe Reader. So rasterizing seems to be the way to go indeed.
JiHO --- http://jo.irisson.free.fr/