Re: [ft] Font rasterization
Is hinting the default for FreeType? Basically yes, but the default font flags is something to be selected by the application. Does it need rewriting to use design metrics? I think so. At least for TrueType, you have to make a distinction between rendering for screens and rendering on paper. TrueType has been designed so that up to a certain size and low DPI values, you should use integer coordinates and hinted glyphs (which should be optimized for a given ppem value), together with B/W rendering and size-specific metrics which can differ enormously from the design metrics. Remember that the whole hinting issue has been invented exactly for that. It was revolutionary 20 years ago; today it's rather a burden. On the other hand, it is fully sufficient if you use integer coordinates without hinting to get excellent results in case the DPI value is sufficiently large. Thus the Qt guy is right: For the UI, the `traditional' way is the right one. From what I understand, the functionality's already in place, and it's just that Qt's not making use of it. Could some of the developers of FreeType comment on the issue? Microsoft's introduction of ClearType (which essentially provides sub-pixel positioning for low DPI values) is a paradigm change, and it took some years to make MS applications support that. I don't know whether Qt on Windows already uses ClearType features. And yes, the functionality is there, at least with the autohinter (and soon with the TrueType engine too). Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Font rasterization
I have recently come across a great article about font rendering, http://www.antigrain.com/research/font_rasterization/ Thanks for the pointer, I haven't known this article. It basically states (and very convincingly illustrates) that the secret to very good font rendering is to use only vertical pixel alignment, [...] So, let me reiterate my main inquiry: is it possible (with freetype) to use vertical hinting and pixel alignment only, leaving subpixel rendering to take care of the horizontal aspect? The `light' autohinting mode disables horizontal hinting (and in case of italic fonts). For native TrueType hinting, a volunteer is working on it right now, implementing better ClearType support. This will probably part of the next FreeType version (to appear still in May) as an experimental feature. For PS fonts, the situation is unsatisfying currently since there are some bugs lurking around which noone has time to take care of. Here, you can't disable horizontal hinting. It has been suggested to use the autohinter for PS hinting also, but again, noone has time to implement it. Werner ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
Re: [ft] Font rasterization
Victor, On 5/11/10, Victor loonyphoe...@gmail.com wrote: Hello! I apologize in advance if this is not the place to ask this question, but freetype doesn't seem to have a forum anywhere, so... I have recently come across a great article about font rendering, http://www.antigrain.com/research/font_rasterization/ It basically states (and very convincingly illustrates) that the secret to very good font rendering is to use only vertical pixel alignment, which I take means to apply hinting only vertically. Horizontally, the article suggests to use subpixel rendering -- that would mean very good scalability and shapes. I have tried many configurations in an attempt to produce the same result ( http://www.antigrain.com/research/font_rasterization/text_ft_antigrain.pngis a handcrafted example of what that would achieve), but horizontal pixel alignment seems to kick in even when disabling hinting completely. This is evidenced by characters having the same width with diffrent sizes. For example, if you scale the line l, its length will increase unevenly: at first it would change very little and then suddenly make a great leap. Either that, or that line would seem to have unevenly distributed spaces between the characters. I'm wondering if I just can't figure out how to configure it all correctly, or if the pixel alignment is built in without the ability to turn it off somehow. Or if maybe it's the creators of web browsers, office suites or desktops environments don't know how to achieve such an effect. So, let me reiterate my main inquiry: is it possible (with freetype) to use vertical hinting and pixel alignment only, leaving subpixel rendering to take care of the horizontal aspect? With regard to pixel alignment, it is certainly possible to render glyphs with a fractional offset with Freetype. This is set with the vector argument to FT_Set_Transform(). Sadly most UI toolkits and all web browsers that I have seen make the assumption that all fonts will be hinted horizontally and as such only calculate the glyph metrics and positioning using integers. -Tor ___ Freetype mailing list Freetype@nongnu.org http://lists.nongnu.org/mailman/listinfo/freetype
