Figures and file formats

Which file format to use?

When processing data (e.g. with python and matplotlib) to create figures, there are multiple options for saving them.

This blog gives some great tips and discussion on this topic, but the key points are summarised below:

• Prefer vector-based formats (svg and pdf)
  • These represent images with points, lines, and curves, so they have ‘infinite resolution’.
  • Raster-based formats like png represent images with pixels, so they will get blurry when zoomed in.
• Use png when you need a raster-based format
  • PNG files are saved with lossless compression, whereas jpg uses lossy compression, which gives rise to artifacts or distortions due to the data when saving.
  • While raster images are not as sharp as vector based, you can mitigate against this by setting the required resolution

    plt.savefig("plot.png", dpi=300)