Resolution

[Carnifex]

This bit is true. An inkjet, dye sub, laser or dot matrix printer will need to print a coloured dot followed by a space followed by a dot again to produce lines so two dots per one line.

This is not so true. Those same kinds of printers will rasterize the lines as part of the printer driver. Only pen plotters and other very specialized hardware will not have to rasterize a vector image to draw it. As such for almost everyones case on this forum, every image will eventually become rasterized.

The advantage to vector art is that it is rasterized at the final device stage and not earlier. But if you run with a resolution that is higher than the expected printing stage then there is not much reason to say that one is better than the other. If you dont know what size image and what device your going to use to print it, or show it, then there is advantage to vector art by not fixing its resolution too early. But then there are other advantages to rasterized images too.

You seem to know alot about pixels and rgb but vector graphics are printed using postscript in a postscript printer (ctp for example). Check it up

Note: most desktop printers are not postscript printers but emulates rhis (i bet you could understand the technical bits more than i could as i not a programmer).

[xpian]

"I am sorry but you got this part is (mostly) wrong. Just stick to 300 ppi in your final print size. Please don't tell people anything else.
Note: yes, there are exceptions to the "300 ppi/dpi" rule."

-- I'll agree that 300 PPI is a good rule of thumb. You're not really going to go wrong with that. You'll also note that this dovetails with much of the advice I've been giving (for instance, the advice that you don't need to make your PPI equal to the DPI of your inkjet printer.) The rest of what I wrote is the result of many years...*ahem* ...I should really just stop and agree to disagree. I'll simply say that I'm not making things up. I've spent hundreds of hours looking closely at printouts from many different kinds of printers over many years, through a loupe, and doing multiple resolution and color gamut tests with both client files and test files, as well as having read many books on these subjects. I'm not going to question your qualifications, but simply clarify my own.

"Telling people that it's ok to print stuff in less than 300 dpi/ppi is just wrong."
--Strictly speaking, it's just not wrong. The PPI you use is directly related to, and limited by, the DPI of the output device. However, as agreed above, 300 PPI is a perfectly fine rule of thumb that will not steer you wrong most of the time.

"And you should also check out what postscript is and how it works. Before you tell other how you think it works."
--PostScript is a page description language, developed primarily to transmit object-oriented content to printers. I haven't personally hand-coded PostScript, but I've known people whose job it was to hand-code it, and I've looked at the code many times. It's an industry standard way of describing vector graphics. It's also very flexible, and it can encapsulate raster data in addition to vector data. In our graphic design workflow 10 or 15 years ago, we used lots of Photoshop .EPS files because they were the only raster format at the time that was PostScript Level 2 compliant, and we were working in a color-managed environment where we needed our RIPs to do intelligent color gamut mapping.

Again, I won't claim to be an *expert* about PostScript, but I do know quite a bit about it and have used it for many years. I'm curious what you thought was incorrect about what I'd said?

[xpian]

"You seem to know alot about pixels and rgb but vector graphics are printed using postscript in a postscript printer (ctp for example). Check it up
Note: most desktop printers are not postscript printers but emulates rhis (i bet you could understand the technical bits more than i could as i not a programmer)."

--We used to buy the PostScript RIP modules for our printers years ago, with the primary reason being speed. Though it makes the model of printer more expensive, it's nice to be able to quickly print your file across the network and have the PS module do most of the work for you, freeing up your production computer's CPU. Especially for large files. It's also nice, depending on your workflow, to be able to simply "dump" a .ps file onto your printer and have it plow through it on its own, without having to open the file. But you don't need to have a PS module on your printer to be able to print vector graphics, or files like EPS or PDF that have postscript data in them. As you note in your "emulates" sentence, the app you're using on your computer is capable, through the use of the OS and the installed printer drivers, of transmitting printable data to the printer in whatever form it needs it.

[Redrobes]

It's also nice, depending on your workflow, to be able to simply "dump" a .ps file onto your printer and have it plow through it on its own, without having to open the file. But you don't need to have a PS module on your printer to be able to print vector graphics, or files like EPS or PDF that have postscript data in them.

Yes, the file is vector but the printer rasterizes it internally. If you use a normal inkjet printer then the printer driver in the PC will rasterize it and send over bitmapped data compatible with the print head. If you have a postscript printer then the vector file is sent to the printer and the printers own on board CPU will rasterize the file into a bitmap itself before printing. Unless its an analog pen plotter then something is going to rasterize it. This is the reason why some printers come with such huge memory modules. Its not only to hold the vector file in a buffer but also to hold the rasterized image prior to sending to the laser head.
PostScript is just a language for printing. EPS is just encapsulated postscript in a standardized file format container. PDF is Adobe's portable doc file which contains post script and post script type elements. The file format is nothing to do with the *how* a printer prints the file.
It is usually better to keep a vector file on the PC because its smaller and you let the printer rasterize it to its best capabilities that only it knows. BUT it is still true that if you had a bitmap that was of significantly higher resolution than the internal printer rasterizer resolution then it would look almost identical since the printers re-rasterized version of it would be about the same as if it had been given the vector format. So vector file is much better in this regard but you lose the features of a bitmap when editing it which may or may not be to your advantage.

[Gudern]

I would appreciate that you don't polute my question by irrelevant discussions about printing. That is not what I asked. If my question interests other people, the thread should have finished one page ago when Redrobes gave the relevant answer.
Open another thread about printing if that interests you.
Thanks.

[xpian]

Good job Redrobes. I have nothing to add to that.

Sorry, Gudern, we got a little carried away.

[Redrobes]

Yes - apologies for the thread hijack. This resolution thing has been one of a couple of topics which keeps getting queries since time immemorial. The problem is that if its not addressed to some degree then it gets re-quoted incorrectly over and over in many more posts. Scale and why we have large scale mapping at street level and small scale for continents is another one that comes to mind. But your right to chide us for going on a bit too long. I'll let my tut do my talking and shut up now.

[Carnifex]

I would appreciate that you don't polute my question by irrelevant discussions about printing. That is not what I asked. If my question interests other people, the thread should have finished one page ago when Redrobes gave the relevant answer.
Open another thread about printing if that interests you.
Thanks.

Sorry for high jacking. Hope you got helped!?