PDF format with Type 1 fonts (scalable), not Type3 (bit mapped)
Most conferences require you to submit papers in PDF format with Type 1 fonts. The Python plotting library, matplotlib
, uses Type 3 fonts by default
Check PDF file for fonts via Document Viewer
Open the PDF File and go to properties ->Fonts.
It will show you output as below :

Check PDF file for fonts via Linux command line
Type the following command with pdf file as argument –
pdffonts file_name.pdf
It will output as below, the second column shows the font type.

FIX IT!!
Most of the times default Type 3 font is used while generating plots or figures using matplotlib. You could change the default font to type 1 by adding these 3 lines to your matplotlib script file –
import matplotlib
matplotlib.rcParams[‘pdf.fonttype’] = 42
matplotlib.rcParams[‘ps.fonttype’] = 42
Now if you regenerate your plots PDF file, it will be using Type 1 font.