1

I have some questions about why some fonts appear blurry in math mode.

I have three examples:

amssymb:

\usepackage{amssymb}
\begin{document}
    \begin{equation}
        x \in \mathbb{N}
    \end{equation}
\end{document}

amssymb

bbold:

\usepackage{bbold}
\begin{document}
    \begin{equation}
        x \in \mathbb{N}
    \end{equation}
\end{document}

bbold

bbm:

\usepackage{bbm}
\begin{document}
    \begin{equation}
        x \in \mathbbm{N}
    \end{equation}
\end{document}

bbm

Out of the three examples, why do the last two appear blurry?

4
  • 2
    Probably because you do not have the corresponding type 1 fonts. Only bbold exists in type 1 version, not bbm. The `doublestroke package also defines a blackboard font, which exists in type 1.
    – Bernard
    Commented Apr 7, 2021 at 13:20
  • thanks for the information @Bernard! I tried using fontenc with T1 for bbm but it didn't work and now I know why. I would use bbold but it's not serif so I guess I'll stick with amssymb :) Commented Apr 7, 2021 at 13:28
  • 2
    You misundertood what I wrote: type 1 fonts have nothing to do with the font encoding, they denote Adobe Poscript fonts (hence vector fonts, that can be scaled without problem). The other fonts in your posted in the image are bitmap fonts than can't be scaled.
    – Bernard
    Commented Apr 7, 2021 at 13:32
  • Oh ok, thanks for the clarification! Commented Apr 7, 2021 at 13:34

1 Answer 1

2

They’re using a font format from the late 1970s. When Donald Knuth created TeX, he originally designed a font format named METAFONT, which compiles fonts to bitmaps and was a big step forward. That sufficed to rasterize documents at the resolution of your printer.

However, nobody does that any more. People now compile their papers as PDFs. If you give PDFTeX one of those old-fashioned fonts today, it will do the best it can, compiling the characters to bitmaps and embedding them into the PDF as a Type 3 bitmap font. Unless you happen to view them at exactly the right size, the bitmaps won’t look right. They’ll look jagged and pixelated if you zoom in, fuzzy if you zoom out.

The bbold and bbm packages are only available in this old-fashioned format. You should consider them obsolete. The next font technology that TeX upgraded to was PostScript, and if you’re using PDFTeX, the mathalpha package supports a large set of blackboard-bold alphabets in PostScript Type 1 format. (Two others you might try are dsserif and cmathbb.)

The LuaLaTeX and XeLaTeX engines support OpenType math fonts, through unicode-math. These all come with their own blackboard-bold alphabets. The package also lets you use any TrueType or OpenType font as your \mathbb alphabet.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .