Question about .PS and screen

[mangcang]

Hey, guys. I have some questions bugging me when I read books.

1, Recently I learn that most files should be translated into PS file format to be printed, but I never do that in my printing experience. I mean, we use Photoshop/ Illustrator/Word program,etc and we just Click print and it comes out from printer. That is it. So, I am confused about why books say turn to PS.

2, If wen dont need to turn them to PS files, how can the PS printer understand Photoshop or illustrator or others file formats?

3, I know that if we want to print continuous tone image on offset, we should screen it before print. But if I just want my images printed by normal Inkjet or laser printer instead of offset, should I still screen image? why or why not?

hope you can give me detail to clear my mind. THanks thousands

 

[TerryWyse]

Hey, guys. I have some questions bugging me when I read books.

1, Recently I learn that most files should be translated into PS file format to be printed, but I never do that in my printing experience. I mean, we use Photoshop/ Illustrator/Word program,etc and we just Click print and it comes out from printer. That is it. So, I am confused about why books say turn to PS.

Writing/saving PS files to disk is very old school. The only people I still see doing it are those that are using the PS file to distill to a PDF.

If books are still saying to write PS to disk, they should get a clue....or you should update your library!

2, If wen dont need to turn them to PS files, how can the PS printer understand Photoshop or illustrator or others file formats?

When you hit "print" and it's going to a PS printer, the application and driver is writing the PS file on-the-fly...you never see it. Magic!

3, I know that if we want to print continuous tone image on offset, we should screen it before print. But if I just want my images printed by normal Inkjet or laser printer instead of offset, should I still screen image? why or why not?

Everything that prints needs screened unless it's a true continous tone process (photographic printing and possibly gravure are the only true contone processes that come to mind). In the case of laser printers and inkjets, the screening is usually handled by the driver or by the printer hardware. In the case of inkjet printers of course, it's not "conventional" screening but something that comes very close to continuous tone (error diffusion or a variation of that).

Regards,
Terry

 

[claude72]

Writing/saving PS files to disk is very old school. The only people I still see doing it are those that are using the PS file to distill to a PDF.

Or to send the .PS file to a RIP.

When you hit "print" and it's going to a PS printer, the application and driver is writing the PS file on-the-fly...

... but this file is written temporarily on the hard-drive, and automatically erased when the printing is finished.

Everything that prints needs screened unless it's a true continous tone process...

... or unless it is a line-art picture: line-art (or line-work) picture have only black and white dots that can be printed directly by the printer, avoiding any need of screening.


***********

I know that if we want to print continuous tone image on offset, we should screen it before print. But if I just want my images printed by normal Inkjet or laser printer instead of offset, should I still screen image?

Yes, of course, and for the same reason!

Black and white laser/ink-jet printers are working exactly like an offset press with black ink in the ink-fountain: both can print ONLY black dots, meaning that on the printed paper you ONLY see black (there is ink) or white (there is no ink) areas: both have only two states, meaning that both are unable to output gray-scales with 254 shades of gray...
... so, if you want to print gray areas and/or gray-scales picture, both have to use a screen to simulate the gray levels.


Adding cyan + magenta + yellow to a laser/ink-jet printer, will extend the possible printed colours from 2 to only 8: cyan, magenta, yellow, black, blue (C+M), red (M+Y), green (C+Y) and white... 8 possibilities, but in fact only two states for each ink: "there is ink", "or there is no ink"...
... and again, it is not enough to print a CMJN pictures with 256 levels for each primary color, and again the picture needs to be screened for printing.

 

[mangcang]

Or to send the .PS file to a RIP.

Hey, Thanks your answer and it is helpful.

but how to understand send the PS file to a RIP. As far as I know, some RIP is built in printers, and your guys told me the driver is writting the PS file automatically when I hit the "print", no matter what kind of file created by software, so there is no point in turning files to PS before print.

Therefore, from what I understand, sending the file to a printer is the same as sending it to RIP (built in printers). Is it right? If the printer can automatically writting PS file, why do I bother to turn PS and then send to RIP? or maybe you mean when the driver cant writting the PS, we need wirte PS and send to RIP?

Hope my question isnt confusing you. THanks in advance

 

[mangcang]

When you hit "print" and it's going to a PS printer, the application and driver is writing the PS file on-the-fly...you never see it. Magic

hey, Terry

You mean the application and driver is capable of understanding and translating any file format created by other software (illustrator,etc.) to .PS automatically when I hit "print"? Where is application and driver? In computer or printer?

What happen if I want to sent files on a non-PostScript printer? Do the non-PostScript printers also automatically translate files to some certain language the printer understand without operator involved?

Hope my question not bother you. I am just a beginner. Thanks very much

 

[TerryWyse]

hey, Terry

You mean the application and driver is capable of understanding and translating any file format created by other software (illustrator,etc.) to .PS automatically when I hit "print"? Where is application and driver? In computer or printer?

The application IS Illustrator, InDesign, Photoshop, whatever. The application is what you're using when you hit "Print".

The "driver" is simply the software on your computer that talks to the printer. The printer driver sits between the application that you want to print from and the actual physical printer hardware. Back in the olds days of the Mac, the application would send "Quickdraw" data to the print driver and then convert it to PS so the printer hardware could digest it and rasterize it.

The application and driver conspire to send a Postscript stream of data to the printer. It's not a "file format" per sé. If you were to capture this data stream and save it to your hard disk, you'd then call it a Postscript file.

What happen if I want to sent files on a non-PostScript printer? Do the non-PostScript printers also automatically translate files to some certain language the printer understand without operator involved?

Same thing happens...only in the case of a non-PS printer (for example, a typical inkjet printer) the print driver converts the application data to a format that the printer can deal with. It could be PS data, ESC-P for an Epson, HPGL for an HP printer, etc.

Regards,
Terry

 

[TerryWyse]

Or to send the .PS file to a RIP.

Of course, I left that out because I'm assuming that manually dumping .PS to disk and then downloading to a RIP is something from the past. I can remember doing that back in 1992 but, honestly, is that something people still need to do in prepress in this day and age? I'm sure there are isolated workflows that still need to do that but I think (hope) it's not the norm in 2010.

... but this file is written temporarily on the hard-drive, and automatically erased when the printing is finished.

Yes, but who cares? My point was that it's transparent to the operator....and not something the user has to think about.

... or unless it is a line-art picture: line-art (or line-work) picture have only black and white dots that can be printed directly by the printer, avoiding any need of screening.

It's still getting screened though, it's just getting screened at 100%.

I can appreciate some of these "finer points" you raised but I think this only serves to confuse the original poster since they are obviously a beginner.

Terry