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I'm trying to prepare a print-ready pdf file for a book. The publisher is complaining that horizontal lines (in particular, the lines separating headers and footers from the body, but I think it also happens for fraction bars) are showing up as low-resolution images (less than 72 dpi). I think that the following should be the relevant part of the preamble:

\documentclass[11pt]{book}

\usepackage{ifthen}

\usepackage[paper height=9.21in, paperwidth=6.14in, top=.95in, bottom=.95in, 
inner=.75in, outer=.75in, head height=.6in, =.4in]{geometry}

I am compiling the document to a dvi file, and then converting it to a postscript file using

dvips -R -Poutline  -o filename.ps filename.dvi

The postscript file is then converted to a pdf file using Adobe Acrobat on the PDF/X-1a:2001 setting. I should also note that the document does contain a large number of actual images, all of which are included as eps files and have sufficiently high resolution.

How can I make the horizontal lines come out as having resolution at least 72 dpi? (At least 300 dpi would be ideal.)

Speculation: I can imagine that the -D option in dvips might be relevant, but I don't actually know, and I don't have an easy way to detect the results if I start playing around with it.

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  • I really don't know what tags are appropriate here. If someone does, please re-tag. Sep 9, 2011 at 3:10
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    The Command Line Option Details of the dvips documentation mentions the -P <printer> specifies a config.<printer> configuration file which option sets (amongst other things) the resolution. Perhaps something contained in config.outline is causing this drop in resolution?
    – Werner
    Sep 9, 2011 at 5:12
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    Re detecting the results: pdfimages may help - it will extract lines which are rendered as bitmap images for some reason but not vectors.
    – Ant
    Sep 12, 2011 at 11:10
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    Further to my previous comment: pdfimages reveals that, with the workflow as above but using ps2pdf instead of Acrobat, both fraction bars and horizontal rules are rendered as a 1x1 black image which is stretched to the required size - hence the error with resolution. I'm not sure where in the process this is introduced - the PostScript file is not very friendly to my (relatively inexperienced) eyes. I did notice, however, that when the file is compiled directly with pdflatex the lines are rendered correctly as vectors - would this be an option for you?
    – Ant
    Sep 12, 2011 at 11:30
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    One final note: I believe the distinction between vector and bitmap images in this case is academic - in both cases the instruction is to fill a particular area of the page with a single colour. I.e., despite the publishers' software complaining about low resolution, the lines should look as intended when output at any resolution.
    – Ant
    Sep 12, 2011 at 11:32

1 Answer 1

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To repeat my comment above for the sake of writing a reasonably coherent answer, the reason your publishers' software is complaining is that both fraction bars and horizontal rules are being rendered as a 1x1 black image stretched to the required size.

This is caused by the dvips configuration you're using. If you keep the same workflow, but replace -Poutline with -Ppdf when running dvips, the horizontal lines are rendered correctly. (The pdf configuration is actually a superset of outline, so you're not losing anything from the configuration you had.)

(Edited to add: as a matter of fact, it turns out the only detail you need from config.pdf is D 8000: running

dvips -D8000 -Poutline whatever.dvi

is enough to make this work. -D600 - i.e., a resolution of only 600 dpi - is not. I haven't experimented to see what the cutoff value is!)

Perhaps worth mentioning: alternative workflows would include using pdflatex in the first place, and using dvipdfm to go straight from DVI to PDF.

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  • Thanks! Also, thanks for the tip about pdfimages. The publisher very strongly recommends that pdf files be compiled using Adobe Distiller (on a particular setting), which is why I am going through dvips. Sep 13, 2011 at 4:06

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