| | <<<Back 1 day (to 2017/05/15) | 20170516 |
| Luca__ | Hey Guys! | 10:06.27 |
| | I've got a little question on ps2pdf, anyone online who can help? | 10:08.10 |
| kens | Did you read the welcome message ? | 10:08.23 |
| | Hmm, its changed | 10:08.40 |
| Luca__ | Sorry, i might ahve skipped it | 10:08.51 |
| kens | Anyway, ps2pdf is (in Ghostscript) just a shell script | 10:08.55 |
| sven337 | I guess what kens wanted you to pay attention to is "don't ask to ask" | 10:09.36 |
| | which is a terribly annoying thing on IRC to see people do | 10:09.47 |
| kens | Yeah but we seem ot have dropped that in the last update to the welcome message.... | 10:09.56 |
| Luca__ | ah ah!! Ok, huge apology. | 10:11.06 |
| kens | The short answer anyway is 'yes' and since this channel is logged, and the developers read the logs, you should just ask the question and wait. Or come back later and read hte logs for an answer | 10:11.22 |
| | But note that while I'm willing to help with Ghostscript and the pdfwrite device, not so much with shell scripts. | 10:11.42 |
| Luca__ | Ok, I understand. Thank you. | 10:12.06 |
| | Here is the thing: I would like to switch from Adobe Distille to ps2pdf (faster, batch processing, can run on a much-faster remote server etc) | 10:15.23 |
| | and the command "ps2pdf -dPDFSETTINGS=/prepress input.ps input.pdf" | 10:16.39 |
| | seems to work very well for my needs! | 10:16.55 |
| | I love it. | 10:16.59 |
| | Just, I would be using in a 'production' envieronment | 10:17.30 |
| | I and I'm a bit afraid I overlooked something. | 10:17.54 |
| kens | If you are concerned about the GPL then we cannot realistically give you advice, as there are no lawyers here. | 10:18.11 |
| | However, *using* Ghostscript is not usually a problem | 10:18.24 |
| | If you were supplying a service (eg a web conversion from PostScript to PDF) then that might fall under the provision of the AGPL | 10:18.55 |
| | If you are concerned you should seek competent legal advice | 10:19.08 |
| Luca__ | Is there something I should be carefull about when turning .ps to .pdf to feed a printing machine? | 10:19.21 |
| kens | I suppose the simple question would be 'why bother' ? Doen't your pritner accept PostScript ? | 10:19.48 |
| luca___ | You're very right | 10:22.19 |
| | I just turn everything to pdf the other people in the print chain (printer, binder etc) can view the file on their PC. | 10:23.26 |
| kens | Tell them to use Ghostscript or Ghostview to display the original PostScript :-) | 10:23.50 |
| luca___ | and It's just handy for everyone to have a single (pdf) file to refear to. | 10:23.57 |
| | ah ah! | 10:24.07 |
| kens | Any format conversion carries inherent risks, its entirely possible that the mismatch in graphics model, limitations in the software, or bugs, could cause a conversion from PostScript to PDF to go awry | 10:24.15 |
| luca___ | Ok, so, best pratice is... pratice. | 10:25.01 |
| kens | So there's always a danger with converting from PostScript to PDF. For example, there's a long running thread on comp.lang.postscript (UseNet) about a bug in Acrobat: | 10:26.05 |
| | https://acrobat.uservoice.com/forums/590923-acrobat-for-windows-and-mac/suggestions/19193479-distiller-charpath-clip-stroke-does-not-honou | 10:26.05 |
| luca___ | This makes sense. | 10:26.48 |
| kens | So basically, if it works, fine, if it doesn't then raise a bug report :-) | 10:27.05 |
| luca___ | Ok! I'll go throught the documentation again, making sure that the "/prepress" argument covers by default my requirements. | 10:28.30 |
| | Thank you! | 10:28.34 |
| kens | NP | 10:28.48 |
| | FWIW if it was me I would not use -dPDFSETTINGS | 10:29.01 |
| | I'd leave everything at default unless I had soem really good reason not to. | 10:29.14 |
| | And if I really did need to change some of the defaults, I'd change them individuallu, rather than the scattergun approach of PDFSETTINGS | 10:29.36 |
| luca___ | I see your point | 10:30.42 |
| kens | The defaults try to preserve what was in the input unchanged in the output | 10:31.04 |
| luca___ | It's just that it's very tempting to use that 'shortcut', cause I can see in the doc that many default settings are not suitable for offset printing | 10:31.48 |
| | like ColorImageResolution set to 72 dpi | 10:32.08 |
| | and Bicubic method for ColorImageDownsampleType | 10:32.46 |
| | But I see what you're aiming at. | 10:33.01 |
| | Konowing what happens 'under the hood' always helps getting things right. | 10:33.24 |
| kens | The defaauult is not72 dpi | 10:36.15 |
| | Its 720 dpi | 10:36.19 |
| | And ColorImageResolution is only used if you set DownsampleColorImages, which is false in the default settings | 10:36.41 |
| | Bicubic is the best downsampling filter available, if you want to downsample, you'll want to use that | 10:37.05 |
| | But you would need to turn on colour image downsampling first | 10:37.19 |
| | By default its off, the image in the output will be the same as the image in the input. *provided* its not compressed with JPEG | 10:37.42 |
| | Because in order to create a PDF file Ghostscritp will first decompress the JPEG image. Then it will recompress it again, using JPEG compression | 10:38.11 |
| | Because JPEG is a lossy compression, each application of the compression results in areduced quality. | 10:38.36 |
| | So one thing you *would* want to do if you expect JPEG compressed images, is to set the ColorImageFilter to Flate | 10:39.00 |
| | And that's neither the default, nor the Prepress setting if I remember correctly | 10:39.16 |
| luca___ | Kens, thank you so much! | 12:40.23 |
| | I'm sorry, the documentation was a little misleading on the downsampling rate | 12:41.34 |
| | https://ghostscript.com/doc/current/Ps2pdf.htm | 12:41.43 |
| | and I got the downsampling method wrong. | 12:42.03 |
| | Thank you for the valuable information! | 12:42.21 |
| kens | NP | 12:45.01 |
| | Rather than reading the ps2pdf documentation, read teh vectordevices.htm documentation | 12:46.09 |
| | https://ghostscript.com/doc/current/VectorDevices.htm | 12:46.36 |
| | More complex, but its better information | 12:46.42 |
| | I strongl;y suspect the distiller parameters information in ps2pdf.htm is out of date. I don't keep that document up to date | 12:48.33 |
| | Looks like I should edit ps2pdf.htm and direct people to vectordevices.htm for settings. | 12:51.34 |
| luca___ | Wonderful! Thanks! | 13:10.16 |
| musician_pro | si chiede se gmail non stia funzionando solo a lui | 13:23.45 |
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