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I found out that there's no way to fix WebKit font rendering. But I resolved this issue in alternate way: I used fork of cutycapt which can be found here . It uses QtWebEngine instead of WebKit and properly renders fonts with subpixel AA. It is provided in source code form, so it needs to be compiled. You'll need to install the dependencies: qt5-qmake (to create Makefile), and qtbase5-dev , qtwebengine5-dev , libqt5svg5-dev (Qt modules which are required for compilation). Then you should run qmake and make in the folder with the source code. The resulting CutyCapt file should be placed into the folder with binaries manually or using make install . N.B. There also exists another fork which...
Full answer by whtyger: https://askubuntu.stackexchange.com/a/1568061 (CC BY-SA 4.0).
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