Conversion from true type to T1

Reg's picture

Hello. Few years ago I designed a font (more than one in fact) in true type format and now I want to convert it to Type 1 and Open type. When I do the conversion I see that the font does not retain the quality of the original true type version. Is there a way to convert the font so the curves won't be 'bumpy'? It ain't very bad but this could be better. Thanks for the tips. Reg - I use FontLab 4.04

raph's picture

It's a tricky conversion. If the font is hinted, you will lose the hints entirely. You _can_ mathematically convert quadratic Beziers (TT) to cubics (Type1/CFF) without loss, but you have to make sure not to integer quantize the resulting coords, and you'll get about twice as many control points as strictly needed. I don't know much about FontLab, and whether they've improved their spline math in recent years, but I do know that FontForge can be coaxed into doing this conversion reasonably well [the conversion in the other direction, though, from T1 to TT, sucks, as does the "simplify" tool for trying to reduce the number of control points].

But why convert? TrueType outlines are even more native within OpenType than are Type1's. Type1 is fast becoming a legacy format, so unless there's a special need to support older systems, why not just release in OT with TT outlines?

Miguel Sousa's picture

Yeah, plain Type1 is basically dead: Phasing out "PostScript" Type 1 fonts

Does FL4.04 generate fonts in OpenType format? Version 4.6 will do OTF-CFF (PS-flavored), but not proper OpenType-TT. I believe you'll need FLStudio5 for that.

After converting quadratic B-splines (TT) to cubic Beziers (Type1) with FontLab – don't forget to reverse the contours accordingly –, you could use FL's Optimize operation to remove the superfluous nodes/points. (In FL4.6 it's under Tools->Outline->Optimize)

Here are a few excelent threads related with this topic:
TrueType Versus Postscript
Opentype PS vs Opentype TT
Critiques of the OpenType format?

dezcom's picture

Truetype is cross-platform so I can't see the advantage in conversion to T1. The only advantage is when saving to outlines in Illustrator for manipulation purposes, the T1 curves have fewer points. Other than that, TT does a fine job all round and saves to opentype with no problem.
Miguel, I think FL-4.6 can output to either opentype format. The wording used to describe it all in FL5 is better though.
FOGs "Clean up Paths" does a better job of point reduction than FL-4.6 Optimize , IMHO.


Miguel Sousa's picture

Chris, yes I know that FL4.6 generates both OpenType flavours. But how proper native will the OT-TTs be? The .ttf files will contain the additional tables, but Windows does not recognise them as OpenType, at least not with me. I use FL4.6Mac and on the various occasions I tried, my .ttf OT-TT files never acquired the expected OpenType icon.

> FOGs “Clean up Paths” does a better job of point reduction than FL-4.6 Optimize

I leave that to the experts ;^)

dezcom's picture

Thanks for the clarification Miguel. Hopefully, Microsoft will make there next revisions more OTF friendly. I never use Word for any serious type work so I have little experience with your issue. I am sure you are "The Expert" in many regards Miguel :-)


Miguel Sousa's picture

Come on Chris, April 1st was last week... ;^)

paul d hunt's picture

my .ttf OT-TT files never acquired the expected OpenType icon.

this is because the OT icon is only displayed for TT flavored fonts if the font is digitally signed.

From the thread you referenced earlier on TrueType vs. Postscript:

dezcom's picture

" April 1st was last week… ;^)"

LOL!!! Miguel, I can be a fool every week :-)


Miguel Sousa's picture

Thanks Paul, that had escaped me. (Uau! What a conundrum just to get the right icon...)

Chris, we all are... fools and experts, in a way or another :^)

Diner's picture

Actually, I had always been concerned about going from a 2048 em to a 1000 em in regards to point shifting . . . I have always assumed it's a one way trip that you could go from a smaller to a larger em grid but never the other way around . . .

Stuart :D

paul d hunt's picture

Thanks Paul, that had escaped me. (Uau! What a conundrum just to get the right icon…)

Personally, I think it's all rather silly, as the dsig table is the singular element that determines whether this icon displays or not. For example: you could have a feature-rich TT-flavored OTF without a signature, which does not display the icon. or you could have a simple TT file with no special features that has been signed and DOES display the OT icon. I think this is all very silly and, obviously, confusing to users.

Miguel Sousa's picture

> Personally, I think it’s all rather silly

I agree. Why don't the OS make the decision of changing the icon based upon the presence of font data other than the DSIG table? Microsoft's intelligent approach again? (Can anyone call Simon, please? Or should we create a Si-signal? :^)

dezcom's picture

"...Or should we create a Si-signal? "

Go for it Miguel!


Thomas Phinney's picture

Microsoft has said that they are looking at doing something a bit more sensible for Vista wrt which TT fonts get the OT icon.


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