Hello . Well. First, Keith, I want to thank you for your reply to my message - it was very encouraging and motivated me enough to continue investigation (I'm still convinced WinXP ClearType provides much more readable text output on not-so-highres LCDs than any other technology). Your comments were also very valuable. What I have now : 'reference' (as seen on http://grc.com/cleartype.htm) implementation of 5-level filter. Results are quite promising, although still not on-par with CT (text is a bit more blurry/slightly bolder (sp?) than CT's output). (I could provide results, if somebody is interested). I tend to think this is because either a) MS core TTF fonts supplied with XP probably have some more additional info with proper weighting coefficients (ClearType hints ?). Could someone confirm/deny it ? b) Incorrect/too simple formulae to calculate each subpixel's value distribution. Is there any patent/techdoc info about MS ClearType's used algorithms ? Would it be called 'patent infringement' if such a patent exists and similar technique will be implemented in Xft ? And one more question, this one must probably go to freetype-devel ml, but in case somebody knows - is there any way to use freetype2's grayscale renderer in monochrome mode - without gray smoothing ? Since AA wll be done on filtering stage, additional grayscale blurring is not only unnecessary, but greatly adds to 'boldness' of visible results. I've looked through src/smooth/ftgrays.c and compressed 'coverage' range from 0..255 to two levels - 0 and 255 (gray_hline(), ftgrays.c:~1394 if (coverage < 96) // Empirically chosen value { coverage = 0; } else { coverage = 255; }; ) This step greatly improves sharpness and readability, while maintaining nice antialiasing, but (of course) introduces (or, rather, emphasizes) rendering artifacts. (Tahoma 10 pt 'k' lower diagonal stem missing few pixels, f.e.). I've tried to understand used algorithm, and it seems it's almost impossible to have non-antialiased output with this renderer. So, the question is - am I wrong or do I need to write new renderer ? The task is simple - just render glyphs with 3x horisontal resolution, without any attempts to smooth resulting bitmap. Or, maybe, some other already existing renderer would suffice ? -- With all the best, yarick at relex dot ru.
