8

I've got some PNG images within my LaTeX document. The quality of the image files is sufficient and the result using LaTeX and viewing the resulting DVI file is quite what I expect - looks good.

But I would need such quality of the images in my PDF files as well. But unfortunately when using PDFLaTeX the images are surprisingly worse quality in the resulting PDF file.

How can the quality for the resulting PDF file be improved?

I think there's happening some kind of rasterization which makes the images showing up in bad quality.

(I tried using dvi2pdf or ps2pdf but the quality of the final PDF was the same. Additionally I would like to have a PDF ToC and the hyperref-pdf features when using PDFLaTeX)

Searching the web I found the following but I'm not quite sure if this helps and were to set the mentioned parameters on my *buntu
http://www.mackichan.com/index.html?techtalk/581.htm~mainFrame

Martin Scharrer
  • 262,582
Meinzlein
  • 827
  • 1
    What format are your image files in? – Jan Hlavacek Dec 17 '11 at 04:47
  • @Jan Hlavacek: They're png image files. – Meinzlein Dec 17 '11 at 09:17
  • 3
    @Meinzlein: pdflatex includes PNG images without altering them, so the quality remains unchanged. Most likely, this is a problem with your PDF viewer, see e.g. http://tex.stackexchange.com/a/10978/2552. What viewer are you using? Have you tried printing the document (the quality should be better in a printout)? – Jake Dec 17 '11 at 09:31
  • @I just played around. The dvi file looks just nice and is even zoomable without loosing to much if the image quality. Good hint with the viewer, I never thought of the reader being the reason. I'll try that. Is PDFLaTex the only way to get a proper PDF file with toc? I don't get the information published under the link mentioned in my first post - can I somehow change the PDFLaTex rasterization? – Meinzlein Dec 17 '11 at 09:36
  • 1
    @Meinzlein: Those parameters don't apply here, that article is concerned with converting from other formats to PNG. You're already using PNG, no conversion (or rasterisation) is taking place. The image is included in your document in the full, unchanged quality, so there's not much you can (or need to) do. What viewer are you using? – Jake Dec 17 '11 at 09:42
  • @Meinzlein: When you click on Settings | Configure Backend in Okular, what backends are shown? – Jake Dec 17 '11 at 09:54
  • @Jake: Thanks for your explanation. I'm using Okular viewer. – Meinzlein Dec 17 '11 at 09:55
  • If they are big pictures and if you are scaling them there might be some downsampling/scaling issues happening there. Try them with their original sizes and see if they are the same and use some other pdf viewer to test. – percusse Dec 17 '11 at 09:56
  • Just tried the Evince viewer and it just looks nice :-) Well at least it's not my pdf file's quality. @Jake: It shows Ghostscript as backend. But why is Okulars viewing quality such bad? – Meinzlein Dec 17 '11 at 09:58
  • @Meinzlein: It's probably not "bad", it's probably just smoothing the image, which would be fine for photos, but not for diagrams or graphs. Maybe you could attach a screenshot to show how the image is displayed in Okular. – Jake Dec 17 '11 at 10:03
  • @Jake: Please see the following link for an example http://img72.imageshack.us/img72/4446/okularscreen.png But why is evince viewing diagrams and graphs AND photographs nive and Okular not? – Meinzlein Dec 17 '11 at 10:09
  • 1
    @Meinzlein: Ah, Okular is not smoothing the image (it doesn't on my system, either), and this is one of the cases where smoothing would actually be better. Since Evince smoothes all images, in this case it looks better. In the case shown at http://tex.stackexchange.com/a/10978/2552, smoothing is undesirable, but generally it's a good idea. I wouldn't worry about this in this case: You know that the pictures are included in perfect quality, and most people would be viewing the file in Acrobat or Evince (both smooth) anyway. By the way, typo in the second last line ("bilogische"). – Jake Dec 17 '11 at 10:13
  • @Jake: Thanks for your help and the given example when smoothing is not desirable. Is there a way to have Okular smoothing images? – Meinzlein Dec 17 '11 at 10:17
  • @Meinzlein: Just an idea: Try using the interpolate option for \includegraphics (works only with pdflatex). It is explain as part of this answer of mine: http://tex.stackexchange.com/questions/32986/what-is-the-advantage-of-using-includegraphics-instead-of-pgfimage-for-ordinar/32989#32989 – Martin Scharrer Dec 17 '11 at 10:50
  • One thing that I find confusing here is that you apparently can include png files in a dvi using latex. I thought that latex can only include eps files, and you needed pdflatex to include a bitmap format like png. Is it possible that something in your workflow vectorizes the png files into eps files for inclusion with latex? That could explain why they scale better. If that's the case, you can convert the eps files into pdf and try including those, they may work better. – Jan Hlavacek Dec 17 '11 at 15:20
  • @JanHlavacek: I didn't find vectorized eps files which were created in my workflow. Don't think that my pngs are vectorized. Is there a another way to have them vectorized as eps? – Meinzlein Dec 20 '11 at 15:54
  • You can vectorize them using convert from the imagemagick package, or with sam2p. I am still wondering how you managed to include png files in a latex document. What editor/IDE do you use? – Jan Hlavacek Dec 20 '11 at 17:06

1 Answers1

6

I'd recommend using vector-based graphics for your images. The best format to save images in is .pdf

With programs like Inkscape, you can draw as you would in MS Paint (and do much more), and because the images are vector-based instead of pixel-based, their quality should be preserved when converting to PDF in any way.

You can also try using the TikZ to program figures directly into your LaTeX file; although it takes longer, the output will never vary during compilations and conversions.

jamaicanworm
  • 29,114
  • 2
    I've got png images and I don't want to draw them by hand. I know about Inkscape and use it if i need a new image, but for this document I've got already png images. I wonder why in the pdf they're such bad quality and in kile editor's preview with the dvi they're just fine. – Meinzlein Dec 17 '11 at 09:14
  • 1
    As commented above by Jake, pdf, jpg and png images are simply embedded in the output pdf file, pdfTeX does not alter them. – eudoxos Dec 17 '11 at 09:34
  • 1
    Just wonder why Okular displays the dvi just nive even with 200% zoom, but the pdf in Okular doesn't look nice with respect to the png images. Is there another way than PDFLaTex to get a full functional pdf with toc etc? – Meinzlein Dec 17 '11 at 09:39