![]() Printers featuring a PS raster image processor (RIP), however, are still relatively expensive:Īlready in the 90s, "software-RIPs" (e.g., ghostscript) became popular. If the book got professionally published, the $10,000,000 industrial printer could process the same PS document to render it at 1200x1200 dpi.Ģ0 year later, the CPU power and available amount of RAM is 4,000 times higher. Instead of equipping every workstation with enough RAM and CPU power to render pages at 200x200 dpi (not to speak about the disk sizes and network throughput one needs to store and transfer the resulting documents), it was enough to have one $10,000 laser printer to do the job for the complete department. Industrial printing machines used by publishers were already able to cope with much higher resolutions.īy delegating the computational intensive part to use-time, that is, the printing device, PS provided portability between all these devices and made it possible to prepare high-quality documents even on affordable computers. However, even at that time, a laser printer was able to print a page with 200x200 dpi or more. Going higher (300x300 or 600圆00 dpi) was basically impossible. ![]() ![]() Rendering a complete A4 page at 150x150 dpi resolution on such a system was already challenging. In the 80s a decent workstation (VAX-11) was able to compute 1.5 million instructions per second (MIPS) and was equipped with maybe 1 MiB of RAM.In PDF, all calculations have be completed when the PDF file is produced.Īt its time, the PS model had some clear advantages:.PS is a (Turing-)complete language that permits to defer arbitrary computations to rendering time, that is, when the PS file is used (i.e., printed).There is a great Q&A that discusses the fundamental differences between Postscript (PS) and PDF from a technical perspective:įundamental differences : PSTricks, TikZ/PGF and others, but misses a bit on the (historical) significance of these technical differences:īasically, the technical differences are: ![]() Updating the existing tool chains to PDF would require a massive investment. Postscript has been a long-lasting and broadly accepted standard. With PDF such a tweak is much more complicated.įrom a publishers perspective, I think, the only fundamental reason is legacy software. With Postscript, doubling the line width in the whole document is easily accomplished by putting userdict /setlinewidth put If, for instance, line art in a document is too faint, the publisher may want to enhance it a bit globally before giving the document to press. One feature that makes Postscript the preferred format, in particular for a publisher, is its editability. And if you have a Postscript printer, it can do these computations for you. It can even solve differential equations. The Postscript based PSTricks package is an example that heavily makes use of graphical computation. PDF shows just the result (after some conversions, sometimes called "Distillation") of the computation Postscript is able to do. Postscript is still used as an intermediate document format, since it is a fully fledged programming language allowing you to compute graphics, which PDF doesn't.
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