Re: [ft] Bytecode hinter producing bad results, seems to be a regression
On Sun, Jan 02, 2011 at 08:07:03AM +0100, Werner LEMBERG wrote: The trickyness is that you are trying to separate hinting from rasterizing. As explained already, the TrueType bytecode interpreter and the rasterizer do interact. It's not intended to be handled separately. I went through the trouble of tweaking my 3rd party library to support rendering with FreeType...and the result was identical to when I extract the outlines with FreeType and render things myself! So I guess my font sucks? Where are the good fonts? You might look at the original Helvetica font from Adobe, or its freely available clone from URW, `Nimbus Sans', which comes with Ghostscript. Those fonts use PS hinting technology, not TrueType. How do fonts such as the Linux Libertine family stack up in this regard? Would that be an ideal TrueType font for comparison, or are there better examples? Regards, -- Stuart Longland (aka Redhatter, VK4MSL) .'''. Gentoo Linux/MIPS Cobalt and Docs Developer '.'` : . . . . . . . . . . . . . . . . . . . . . . .'.' http://dev.gentoo.org/~redhatter :.' I haven't lost my mind... ...it's backed up on a tape somewhere. ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
I'm ashamed to admit it but you are talking about things that are going WAY over my head. I tried to use those programs fontforge and ttx but I failed to get them to run. Something about needing Cygwin, which also generated errors when I tried to install that, and I don't understand TTX. So my code is supposed to dig into the font file and figure out if hinting is supported? I thought FreeType was plug and go... I just want to open the font and get hinted outlines without worrying. What is a monochrome rendering and how do I test it under Windows? I'm not using FreeType to render...just to extract outlines. And by the way, the autohinting module works pretty damn good! --- On Sat, 1/1/11, Werner LEMBERG w...@gnu.org wrote: From: Werner LEMBERG w...@gnu.org Subject: Re: [ft] Bytecode hinter producing bad results, seems to be a regression To: thev...@yahoo.com Cc: freetype@nongnu.org Date: Saturday, January 1, 2011, 9:43 AM check your font whether my assumption is correct. I only have `Helvetica Neue LT Pro 65 Medium' version 001.000 (from 2003), but this is an OpenType font with CFF outlines. Accidentally, I've also found `Helvetica Neue LT Com 65 Medium' (2.01 from 2006). My assumption was correct: The `gasp' table of this font asks for monochrome rendering in the range 9-15ppem. However, I see strange hinting for certain ppem values. For example, the monochrome version of `h' at 11ppem misses the left stem, or the `C' at 10ppem lacks the middle part (see attached image). I *can't* believe that this is FreeType's fault, given that those strange rendering results are mainly due to DELTA instructions which shifts certain points at certain ppem values by a fixed amount. Something's is going on here, and it would be interesting to know more details. Do you have a chance to check monochrome rendering of this particular font on Windows? Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
check your font whether my assumption is correct. I only have `Helvetica Neue LT Pro 65 Medium' version 001.000 (from 2003), but this is an OpenType font with CFF outlines. Accidentally, I've also found `Helvetica Neue LT Com 65 Medium' (2.01 from 2006). My assumption was correct: The `gasp' table of this font asks for monochrome rendering in the range 9-15ppem. However, I see strange hinting for certain ppem values. For example, the monochrome version of `h' at 11ppem misses the left stem, or the `C' at 10ppem lacks the middle part (see attached image). I *can't* believe that this is FreeType's fault, given that those strange rendering results are mainly due to DELTA instructions which shifts certain points at certain ppem values by a fixed amount. Something's is going on here, and it would be interesting to know more details. Do you have a chance to check monochrome rendering of this particular font on Windows? Werner inline: C.png___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
The function FT_Get_Gasp tells you, for a given ppem, whether you should render a glyph as monochrome (i.e., black-white) or with anti-aliasing. ppem? is that what I understand to be the font height? Pixels per EM unit? By monochrome I assume you mean, two intensity levels (on or off). As in, an old school bitmap font (like Apple II+). All of my font-drawing is anti-aliased, I'm the middle man passing the grid-fitted control points over to another third party library that I'm using. Why would I ever want to render a glyph as monochrome (two-color) only? TrueType hinting doesn't work like this. For monochrome rendering, the hinting engine also specifies how to rasterize the glyphs (selecting a drop-out mode, for example). From how I interpret those words, I think monochrome rendering is not a use-case for me. I'm not using FreeType to render...just to extract outlines. This is tricky... Can you elaborate? Or tell me anything I should know about that is non-obvious or non-intuitive? I'm actually getting really good results with the auto hinter. I can see very clearly that it is working, and I painstakingly analyzed the output of each glyph to make sure that things are right. Here's a screenshot: This is using the auto-hinter, with FreeType providing the outlines and my 3rd party library (Juce) rasterizing the vector data: http://rawmaterialsoftware.com/download/file.php?id=186 Here is the same output, only with the autohinter turned off. http://rawmaterialsoftware.com/download/file.php?id=185 Here's an animation for comparison http://rawmaterialsoftware.com/download/file.php?id=184 And by the way, the autohinting module works pretty damn good! Then use it! Okay well just to make sure I did things right, I loaded up Adobe Kaiti Std Regular (a thin serif font) and performed the comparisons. First thing I noticed, is the Adobe font is a hefty 16.5 megabytes, while my Neue Helvetica is a wimpy 127 kilobytes. I tried bytecode hinting with the Adobe font and WHOA! amazing outlines! So I guess that my problem is not that FreeType wasn't using my bytecodes, its just that my Helvetica didn't have them. My intuition and eyesight tells me that a font with hints is going to look better with the bytecode hinting than with the auto-hinter. This is definitely the case with this beefy Adobe font. I wish there was a flag to FT_Open_Face that says hey use the bytecode hinter if the font has those hints, or else use the auto-hinter. So now I am going to trying grasping for the Gasp / Grasp whateveritis table and see if I can get some mileage. My goal is to use bytecodes if they are there, else use the autohinter. Thanks ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
You haven't told us which FreeType version you are using... For bug reports, please always try the recent one, this is, 2.4.4. Sorry about that and yes of course I'm using the most recent version. BTW, I'm not sure that `professional' fonts are intended for screen display, working at small ppem values. By professional I mean I went to a website that looked legit (linotype.com) and bought the font, as opposed to just pirating or using something from an unknown foundry. So it seems that the font I have is unhinted, hence the small size. I just assumed that all TrueType/OpenType fonts that came from Linotype or other well recognized foundries were loaded to the gills with hints but it seems I am mistaken. The Adobe font I have seems to have plenty of hints so I will study it. And I will try to find a version of Neue Helvetica 65 Medium that has a full set of glyphs along with hints. Any ideas on where to get that? ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
From: Vinnie thev...@yahoo.com Subject: Re: [ft] Bytecode hinter producing bad results, seems to be a regression Date: Sat, 1 Jan 2011 12:20:06 -0800 (PST) The function FT_Get_Gasp tells you, for a given ppem, whether you should render a glyph as monochrome (i.e., black-white) or with anti-aliasing. ppem? Pixels per EM unit? Yes. By monochrome I assume you mean, two intensity levels (on or off). As in, an old school bitmap font (like Apple II+). Yes. All of my font-drawing is anti-aliased, I'm the middle man passing the grid-fitted control points over to another third party library that I'm using. Why would I ever want to render a glyph as monochrome (two-color) only? Here is the problem: For a certain ppem range, as specified in the gasp table, the particular Helvetica font *expects* B/W rendering! If you do anti-aliasing instead, you get bad results. On the other hand, some B/W rendering results of Helvetica are really bad and I wonder whether this is due to a bug in FreeType or whether this font has simply bad hinting instructions. I'm not using FreeType to render...just to extract outlines. This is tricky... Can you elaborate? Or tell me anything I should know about that is non-obvious or non-intuitive? The trickyness is that you are trying to separate hinting from rasterizing. As explained already, the TrueType bytecode interpreter and the rasterizer do interact. It's not intended to be handled separately. I'm actually getting really good results with the auto hinter. I can see very clearly that it is working, and I painstakingly analyzed the output of each glyph to make sure that things are right. Yes, because the autohinter works completely differently. In particular, it always expects anti-aliased rendering. And by the way, the autohinting module works pretty damn good! Then use it! Okay well just to make sure I did things right, I loaded up Adobe Kaiti Std Regular (a thin serif font) and performed the comparisons. First thing I noticed, is the Adobe font is a hefty 16.5 megabytes, while my Neue Helvetica is a wimpy 127 kilobytes. Kaiti is a font for Chinese. Do you need this? I tried bytecode hinting with the Adobe font and WHOA! amazing outlines! So I guess that my problem is not that FreeType wasn't using my bytecodes, its just that my Helvetica didn't have them. No, no, no! The Kaiti font is *not* a TrueType font (this is, second-order Bezier curves). It's an *OpenType font* using CFF outlines (this is, third-order Bezier curves), and there aren't any bytecode instructions but PS-like hints. Basically, it's a completely different font format; it just happens that both TTFs and OTFs use the SFNT container format, thus they look similar at a first glance. My intuition and eyesight tells me that a font with hints is going to look better with the bytecode hinting than with the auto-hinter. This is definitely the case with this beefy Adobe font. I'm not sure. FreeType's native hinter for third-order Bezier outlines is quite buggy and problematic. I wish there was a flag to FT_Open_Face that says hey use the bytecode hinter if the font has those hints, or else use the auto-hinter. This is impossible to decide by FreeType. On the operating system level, such decisions are controlled by a higher-level library. On Linux, this is done by fontconfig, for example. So now I am going to trying grasping for the Gasp / Grasp whateveritis table and see if I can get some mileage. Note that `gasp' makes only sense for TTFs, not OTFs. My goal is to use bytecodes if they are there, else use the autohinter. I can only repeat that this won't work automatically but needs a user decision. Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
The trickyness is that you are trying to separate hinting from rasterizing. As explained already, the TrueType bytecode interpreter and the rasterizer do interact. It's not intended to be handled separately. I went through the trouble of tweaking my 3rd party library to support rendering with FreeType...and the result was identical to when I extract the outlines with FreeType and render things myself! So I guess my font sucks? Where are the good fonts? Are there some example fonts with well defined properties floating around that I can test with? Kaiti is a font for Chinese. Do you need this? Hmm...I don't know about that, it just got installed along with Photoshop and I grabbed it out of my Fonts folder and tried it with my code to see how it would perform with serifs (which I imagine require more hinting work?). No, no, no! The Kaiti font is *not* a TrueType font (this is, second-order Bezier curves). It's an *OpenType font* using CFF outlines (this is, third-order Bezier curves), and there aren't any bytecode instructions but PS-like hints. Oh my...why did they make fonts so confusing? ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
So it seems that the font I have is unhinted, hence the small size. No. It's hinted. I just assumed that all TrueType/OpenType fonts that came from Linotype or other well recognized foundries were loaded to the gills with hints but it seems I am mistaken. Helvetica originally is a Type 1 font from Adobe which has been later converted to TrueType. This conversion process was obviously done semi-automatically, and I suspect that all hinting bytecode instructions have been applied by a program, not by a human, thus the bad quality for B/W rendering at such small ppem values. Remember that this font is intended for printing, not for displaying fine on the screen. The Adobe font I have seems to have plenty of hints so I will study it. It's different technology... And I will try to find a version of Neue Helvetica 65 Medium that has a full set of glyphs along with hints. Any ideas on where to get that? The font *is* complete. If you want better hinting for such small ppem values I suspect that you need a different sans-serif font which has been specially tuned for screen usage, like Arial. Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Bytecode hinter producing bad results, seems to be a regression
The trickyness is that you are trying to separate hinting from rasterizing. As explained already, the TrueType bytecode interpreter and the rasterizer do interact. It's not intended to be handled separately. I went through the trouble of tweaking my 3rd party library to support rendering with FreeType...and the result was identical to when I extract the outlines with FreeType and render things myself! So I guess my font sucks? Where are the good fonts? You might look at the original Helvetica font from Adobe, or its freely available clone from URW, `Nimbus Sans', which comes with Ghostscript. Those fonts use PS hinting technology, not TrueType. No, no, no! The Kaiti font is *not* a TrueType font (this is, second-order Bezier curves). It's an *OpenType font* using CFF outlines (this is, third-order Bezier curves), and there aren't any bytecode instructions but PS-like hints. Oh my...why did they make fonts so confusing? Historical development. You might read this old article: http://www.truetype-typography.com/articles/ttvst1.htm The English article on Wikipedia about OpenType gives further hints too. Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
