Re: Does Freetype work best with gamma 2.2, and how does it interact with KDE gamma setting?

[Rob]

In case anyone is interested, attached is the same font rendered in both .ttf 
and .otf versions using KDE Plasma Qt5 desktop.

A subtle difference, yet I guess the otf is more "correct".
On May 4 2021, at 11:49 am, Allan Sandfeld Jensen <linux@carewolf.com> wrote:
> I would leave it at 1.0. Not sure what it is supposed to affect now though. It
> used to do something directly to the screen (to counter screen glare in bright
> sunlight for instance). Now it seems unresponsive/dead to me though. You
> should probably ask KDE/Plasma.
>
> Allan
> On Dienstag, 4. Mai 2021 12:33:54 CEST Rob wrote:
> > Perhaps it's outside the scope of this mailing list, but in that case should
> > I calibrate my monitor to a gamma of 1.7 to get the best text rendering?
> >
> > On the other hand, this link indicates that a relative system gamma of "1.0"
> > is equivalent to 2.2 on windows, so perhaps a monitor calibrated to 2.2 is
> > actually correct.
> > https://docs.kde.org/stable5/en/kgamma5/kcontrol/kgamma5/index.html
> > (https://link.getmailspring.com/link/E256C570-0F27-4E81-8AF8-8EF045BB93CC@g
> > etmailspring.com/0?redirect=https%3A%2F%2Fdocs.kde.org%2Fstable5%2Fen%2Fkgam
> > ma5%2Fkcontrol%2Fkgamma5%2Findex.html&recipient=bGludXhAY2FyZXdvbGYuY29t)
> > On May 4 2021, at 11:29 am, Allan Sandfeld Jensen <linux@carewolf.com>
> wrote:
> > > Qt5 uses a gamma of 1.7 for text rendering on X11.
> > >
> > > The KDE gamma slider is an effect on the whole screen, not how elements
> > > are
> > > blended together inside singular apps.
> > >
> > > Not sure there is any other place we could read an expected gamma from on
> > > Linux, the only other source is using real gamma from monitors EDID, but
> > > that would result in a much higher gamma and lighter text, probably not
> > > fitting user expectations. Though perhaps we ought to have a switch
> > > allowing users to use real numbers instead of simulating traditional
> > > mistakes.
> > >
> > > Allan
> > >
> > > On Dienstag, 4. Mai 2021 12:20:38 CEST Rob wrote:
> > > > Ok, I understand.
> > > >
> > > > I am using KDE so I guess qt5 is responsible for gamma correction (and
> > > > probably assumes monitor is 2.2).
> > > >
> > > > On May 4 2021, at 10:53 am, Werner LEMBERG <wl@gnu.org> wrote:
> > > > > > But if it is correcting the gamma it must assume that my monitor has
> > > > > > a certain gamma?
> > > > >
> > > > > As Allan has written: FreeType does *not* interact with gamma at all!
> > > > > If you want to be very precise you could say that FreeType doesn't
> > > > > return bitmaps with color or grayscale pixels. Instead, it returns
> > > > > *coverage* values (i.e., how much area of a pixel is covered by ink),
> > > > > and the calling graphics library has to further process it. This
> > > > > includes application of gamma correction.
> > > > >
> > > > >
> > > > > Werner
>

gamma_ttf.png
Description: PNG image

gamma_otf.png
Description: PNG image