Type 1 rasterisation is highly dependent on the renderer used, although, of course, the quality of the font does matter. All of the following samples use Linotype Times Roman, as distributed by Adobe and included in most PostScript products.
The Adobe Type 1 rasteriser is the reference.
The X11R6 Type 1 rasteriser was donated by IBM and is not
quite as good as the Adobe one.
Neither is GhostScript 5.10. Notice how serifs disappear at small sizes.
The rendering of a TrueType font depends crucially on the quality of the font. Those samples use Monotype Times New Roman, as included by Microsoft in their `core fonts'. Don't expect to find many TrueType fonts that display that well!
The Adobe rasteriser produces good results.
As does the FreeType rasteriser in Xfsft.
And the rasteriser in Xfstt.
GhostScript does not currently support
instructions, and, at 72 dpi, the results look horrible. Note,
however, how uniform is the weight of the different sizes.
As the Adobe rasteriser shows, and contrary to popular belief, it is possible to achieve great on-screen quality with Type 1 fonts. While the quality of the rasterisation of TrueType fonts depends solely on the font used, in the case of Type 1 fonts it depends greatly on the rasteriser.
As it is significantly easier to produce high-quality Type 1 fonts than TrueType fonts, it is unfortunate that there is currently no good Free Type 1 rasteriser available. This may change when FreeType 2 is released.
Acrobat Exchange does sub-pixel positioning of glyphs.
Note, for instance, the differences between the two `o' glyphs in
`dolor' at small sizes:
.
Those are actual unmodified screenshots of applications running under X11 with anti-aliasing disabled. The fonts have been rasterised at sizes ranging from 10 to 20 points at a resolution of 72dpi. The programs used for the rendering were:
as well as a couple of throw-away programs written in PostScript and C.
TrueType, PostScript, Adobe, Acrobat, Times Roman, Times New Roman, Linotype, Monotype, Microsoft, Unix, and possibly others are trademarks or registered trademarks of their respective owners.
Copyright © 1998-1999 by Juliusz Chroboczek
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