Good quality images in pdflatex

Question

Generally I include images in my latex document by the command

\includegraphics[scale=0.5]{image.png}

However, after doing pdflatex the image quality is always very poor in the resulting pdf file. I think it is probably due to the scaling I do. I have also tried pdf, ps and eps images but they also suffer the same problems. I generally use gnuplot or matplotlib to generate the graphs.

What format should I store the images so that when I scale them to be put in the latex document, they maitain their quality? What are the macros that I should use? As of now I only use

\usepackage{graphics}

Answer 1

For diagrams you will get the best results when using vector graphics. Both gnuplot and matplotlib can export to vector graphics; file formats for vector graphics are e.g. eps or pdf or svg (there are many more).

As you are using pdfLaTeX, you should choose pdf as output format, because it will be easy to include in your document using the graphicx package and the \includegraphics{} command. To show you how to do it, I went to the matplotlib gallery and downloaded one of the many examples, saving it as myplot.pdf. The following code gives me absolutely satisfying quality.

\documentclass{article}

\usepackage{graphicx}
\usepackage{blindtext}

\begin{document}
\section{Introduction}
Some text and \Blindtext .
%
\begin{figure}%[!thb]
  \centering
  \includegraphics[width=0.8\linewidth]{myplot.pdf}
  \caption{The figure caption should go below the figure.}
  \label{fig:myplot}
\end{figure}
%
Some more text and \blindtext and a reference to figure~\ref{fig:myplot}.
Even more text and the end of the text.
\end{document}

PS: As discussed here, jpg is good for photos, png is good for e.g. screenshots.

Answer 2

The format of the graphic depends on the content. JPG is good for pictures, PNG was designed for content containing text.

For good print you will need a solution of at least 300 dpi.

Using a PDF as a container will not solve the problem of a poor graphic. So look at the format and the dots per inch of the image.