These are examples of files that have gone the route DVI → PS → PDF, where the PS file contained Type 3 (bitmap) fonts without hinting instructions for on-screen viewing. If you have the original PS file you can often fix them with Heiko Oberdiek's amazing `pkfix` (and `pkfix-helper` if needed) tool [1].
(You can zoom the PDF to 500% to see the font's glyph shapes down to actual pixels; this pixelation is not inherently a problem as these PDFs look fine when printed on a typical high-resolution printer: try it!)
In more detail for your example PDF [2]: running `pdfinfo` gives:
$ pdfinfo H-SIGMOD1999.pdf
Title: main.dvi
Creator: dvips 5.58 Copyright 1986, 1994 Radical Eye Software
Producer: Acrobat Distiller Command 3.0 for Solaris 2.3 and later (SPARC)
CreationDate: Thu Jan 24 16:43:42 2002 PST
So presumably:
• `main.tex` has been typeset with TeX into `main.dvi` at some point (the paper has a "September 1998" and "SIGMOD 1999" in the title, so presumably it's from then),
• This `main.dvi` has been converted into a `.ps` file at some point, using dvips 5.58 from 1994 (dvips 5.70 was in 1997).
• This `.ps` file has been converted into `.pdf` using Acrobat Distiller on SPARC, presumably in 2002.
Now, with some searching online we can actually find the original PS file: it's at [3] (and dated "24-Sep-1998 19:15"). The dvips version 5.58 is too old for pkfix to run its magic directly, but by running pkfix-helper first (which does guessing based on font metrics, and in this case seems to have guessed mostly correctly: though the superscript font for footnotes is wrong), and then pkfix, and then converting to PDF, we get this equivalent I just made (compare with your example [2]): [4]
These are examples of files that have gone the route DVI → PS → PDF, where the PS file contained Type 3 (bitmap) fonts without hinting instructions for on-screen viewing. If you have the original PS file you can often fix them with Heiko Oberdiek's amazing `pkfix` (and `pkfix-helper` if needed) tool [1].
(You can zoom the PDF to 500% to see the font's glyph shapes down to actual pixels; this pixelation is not inherently a problem as these PDFs look fine when printed on a typical high-resolution printer: try it!)
In more detail for your example PDF [2]: running `pdfinfo` gives:
So presumably:• `main.tex` has been typeset with TeX into `main.dvi` at some point (the paper has a "September 1998" and "SIGMOD 1999" in the title, so presumably it's from then),
• This `main.dvi` has been converted into a `.ps` file at some point, using dvips 5.58 from 1994 (dvips 5.70 was in 1997).
• This `.ps` file has been converted into `.pdf` using Acrobat Distiller on SPARC, presumably in 2002.
Now, with some searching online we can actually find the original PS file: it's at [3] (and dated "24-Sep-1998 19:15"). The dvips version 5.58 is too old for pkfix to run its magic directly, but by running pkfix-helper first (which does guessing based on font metrics, and in this case seems to have guessed mostly correctly: though the superscript font for footnotes is wrong), and then pkfix, and then converting to PDF, we get this equivalent I just made (compare with your example [2]): [4]
[1]: https://en.wikipedia.org/w/index.php?title=Pkfix&oldid=10194... and https://ctan.org/pkg/pkfix-helper?lang=en
[2]: https://courses.cs.duke.edu/spring02/cps296.1/papers/H-SIGMO...
[3]: https://www1.icsi.berkeley.edu/ftp/global/global/pub/techrep...
[4]: https://shreevatsa.net/post/2022-pkfix-etc/tr-98-033_pkfix-h...