Having pixel-peeped a lot of freetype text, the differences you are seeing look very similar to that between a 5-tap beveled filter (current default), and light or no filtering.
The lower "orange/blue" is what I would expect, and is pleasant to look at. The upper "yellow" is a harsher rendering. So perhaps you have a personal preference for lighter or no-filtering which can easily be changed in your font config. My general opinion, is that FreeType 2.10 with the default filter gives a perfectly balanced rendering on a range of machines I run it on. In fact I am amazed they managed to tune it so nicely. On Mar 15 2021, at 11:42 am, Peter <su...@web.de> wrote: > > > Am 09.03.21 um 11:55 schrieb Werner LEMBERG: > > > >> Here are two more images that contrast the rendering output of > >> FreeType 2.6.1 with that of a patched version of FreeType 2.10.1 > >> using the old default LCD filter. The filter definitely has a > >> conceivable impact that brings the output closer to that of FreeType > >> 2.6.1. But there are still differences especially concerning the > >> saturation of the outer blue shades of the glyphs (some of which I > >> have marked). > > > > Have you actually played around with the `ftview` tool? Right now, > > this is the only recommendation I can give to exactly find out what's > > going on... > > > > > > Werner > > > Yes, I did. I tried to reproduce the output of version 2.6.1 of the > 'ftview' demo tool with version 2.10.1. But even with the exact same > settings (hinting, gamma, LCD filter etc.) the output that version > 2.10.1 produces differs from that of version 2.6.1. > > The fonts rendered with version 2.6.1 are darker and their stems > thicker. I'm not sure how to describe this properly, but I also perceive > the fonts rendered with version 2.6.1 as sharper than their counterparts > rendered with version 2.10.1. > > I have attached several images and comparisons of the respective outputs > that hopefully make this difference apparent. The text strings in the > comparison images are taken from the two 'ftview' outputs. The upper > string is in each case taken from the output of version 2.6.1 of the > 'ftview' demo tool and the lower one from version 2.10.1. >