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What are the differences between the original (rasterized) CM fonts and the current (smooth PDF-friendly) type1 versions of these fonts?

It seems to me that the originals are much better looking. They are "thicker". You can clearly see the difference in printed output. The type1 ones are somewhat "thinner".

Why is this? Why aren't they exactly the same?

And final question: On a modern MacTeX distribution (on my Mac OS X), how can I compile my document with the older fonts?

Update: I feel the current answers haven't answered some of the sub-questions and, more importantly, haven't provided the proper understanding that I'm looking for. The question can be rephrased: I look at "Digital Typography" by Knuth and a recent mathematics book on my shelf. Both are clearly printed in very high resolution—the fonts are smooth and look how they are supposed to look. But the font in Knuth's book is far more "thicker" and has a much more warmer, juicier, and nicer feel to it. On the other hand, I recognize the font in the mathematics book as the modern ubiquitous "smooth type1" CM font. In comparison to the font in Knuth's book, it looks thin and pale. I'm looking for some foundational understanding for why this is the case and why it turned out this way. Any font experts in here?

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5  
It might be that MetaFont does a better job rasterising the fonts for small sizes than what PostScript raseterisers do (e.g. it might have some meta-info about the fonts that the PS outlines does not have). –  Khaled Hosny Mar 17 '12 at 17:06
    
i don't think this really answers your question, but have a look at this answer that touches upon the same topic. it discusses the older font encoding's problems with hyphenation and copy/paste. it also references ot1 and t1 examples which made me think "wow, they are thicker!" –  asia1281 Mar 20 '12 at 3:56
1  
Which resolution uses your printer? At which resolution were the PK fonts generated? Could you please include a scanned image of an actual printed sheet which shows the difference you stated? –  JLDiaz Mar 22 '12 at 16:44
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4 Answers 4

up vote 18 down vote accepted
+50

sorry, @Herbert, the image doesn't say it all.

what was neglected in the description is that metafont was run at a particular resolution to produce the first image, which, when scaled up, shows the artifacts of bitmapping.

here is a counterexample, adding in to your first test the type 1 cm fonts scaled in the "plain tex manner", along with the file that produced it. during the tex run, mf was launched automatically, with this report:

kpathsea: Running mktexpk --mfmode / --bdpi 600 --mag 1+0/600 --dpi 6000 cmr10
mktexpk: Running mf-nowin -progname=mf \mode:=ljfour; mag:=10+0/600; nonstopmode; input cmr10
This is METAFONT, Version 2.718281 (TeX Live 2010)

the output:

test of three cm/lm strings to compare shapes

that said, it's possible to see small differences -- the right-hand stem of the M and the stem of the R look thicker in the cm than in the lm. so i conclude that the type 1 cm fonts are more "true" to the original mf cm than are the lm fonts; nearly everyone these days except knuth uses the lm fonts because they're superior in many ways for work in languages other than english.

for folks who want to try this out for themselves without retyping, here's the input code; i didn't realize it wasn't possible to cut-and-paste from an embedded pdf image. (i included the code as "proof" that it was exactly what produced this output.)

\documentclass{article}
\pdfmapfile{lm.map}
\usepackage{graphicx}
\usepackage{verbatim}

\begin{document}
\thispagestyle{empty}
\noindent
\scalebox{10}{CMR}\\[10pt]
\font\bigfont cmr10 at 100pt
\bigfont CMR\\[10pt]
\fontfamily{lmr}\selectfont
\scalebox{10}{CMRL}

\vspace{2\baselineskip}
\verbatiminput{\jobname.tex}
\end{document}
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Could the input code be part of the text of the answer, rather than an image? (I'd retype it myself, but I guess you've got the original available.) –  Joseph Wright Mar 22 '12 at 16:04
    
@Joseph -- i included it in the answer to "prove" that this was the code that produced the output. i didn't realize it wasn't possible to cut-and-paste from an embedded pdf. i've added the code, but left the duplicate in the pdf; hope nobody minds. –  barbara beeton Mar 22 '12 at 16:12
    
@barbarabeeton: The pdf actually gets automatically converted to png when you upload it. Copying out of a png is not possible, of course. –  doncherry Mar 22 '12 at 16:23
    
@doncherry -- thanks. didn't realize this became a png insert. (some things i prefer to leave as "black boxes".) –  barbara beeton Mar 22 '12 at 16:33
1  
Not only MF can generate fonts at every resolution, but the raster files can be quite generally adaptable to each printing device. Something of this kind is available with hinted Type1 fonts, but not as generally as with MF. –  egreg Mar 22 '12 at 17:12
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The image says it all ...

\documentclass{article}
\pdfmapfile{lm.map}
\usepackage{graphicx}

\begin{document}

\scalebox{10}{CMR}
\fontfamily{lmr}\selectfont
\scalebox{10}{LMR}

\end{document}  

enter image description here

or the same with only cm fonts:

\documentclass{article}
\pdfmapfile{cm-super-t1.map}
\usepackage{graphicx}

\begin{document}

\scalebox{10}{CMR}
\fontencoding{T1}\selectfont
\scalebox{10}{CMR}

\end{document}    

enter image description here

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3  
Whilst this shows the obvious difference between vector and raster, it doesn't explain the difference in print. As Enchilada notes, one would expect identical results on paper. –  qubyte Mar 17 '12 at 15:44
    
The above images are in original size! So its obvious that you didn't get the same when printed. –  Herbert Mar 17 '12 at 15:49
    
And for smaller sizes? The question doesn't mention pixellated fonts. In fact, it suggests that they look better. –  qubyte Mar 17 '12 at 16:10
    
I have noticed a difference between T1 and IL2 encoding as well, IL2 seems to produce the "thicker" glyphs. –  tohecz Mar 17 '12 at 16:33
1  
For the non-vector fonts, the printer setting makes a big difference. –  Jim Hefferon Mar 17 '12 at 17:00
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The original Metafont fonts are most likely better if they are used at their design size with the correct Metafont mode for the current output device: Metafont is probably the best rasterizer there is (it has been designed by DEK, after all). The type1 fonts may be better at other type sizes. But I doubt that many people still use the Metafont fonts; today we mostly create PDF.

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Take a look at question (and the answers) Fatter Computer Modern. Basically, the reason is that, for a given outline, the Metafont rasterizer produces a "fatter" set of pixels than the current Postscript and PDF rasterizers. And, with Metafont, you can even tune the rasterization to the properties of the printer.

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