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  1. Qt
  2. QTBUG-95336

CFF fonts appear emboldened on high-resolution displays due to stem darkening

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.9, 6.2.0 Beta1
    • Fix Version/s: None
    • Component/s: GUI: Font handling
    • Labels:
      None
    • Platform/s:
      Linux/X11

      Description

      Since Qt 5.9, Qt enables Freetype's "stem darkening" of CFF fonts (https://code.qt.io/cgit/qt/qtbase.git/tree/src/gui/text/freetype/qfontengine_ft.cpp#n151). This may improve rendering on low-resolution displays, but makes fonts appear emboldened on high-resolution displays. It should thus be enabled on low-resolution displays only in my opinion.

      Normal rendering without stem darkening:

      Artificial emboldening by Freetype's stem darkening:

      The Freetype documentation also states that stem darkening is intended for low-resolution displays, see  https://www.freetype.org/freetype2/docs/reference/ft2-properties.html:

      Stem darkening emboldens glyphs at smaller sizes to make them more readable on common low-DPI screens when using linear alpha blending and gamma correction, see FT_Render_Glyph.

        Attachments

        For Gerrit Dashboard: QTBUG-95336
        # Subject Branch Project Status CR V

          Activity

            People

            Assignee:
            esabraha Eskil Abrahamsen Blomfeldt
            Reporter:
            jkraemer Joshua Krämer
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              Dates

              Created:
              Updated:

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