Pillow ImageFont is different in docker/Alpine and Ubuntu

I created images for my display interface with python Pillow 4.0.0 library. I programmed a script which puts my text into the pillow picture and after converts it to a bitmap which is sent to the display.

I write text in the picture with ImageFont:

ImageFont.truetype('my_fonts/font.ttf', font_size)

Everything works fine in Ubuntu.

When I run the same programme in a Docker Alpine container with the same version of Pillow, the output is not as good as in Ubuntu:

I hope that is recognizable (it is only 192x64px). It is not because of the fonts - all commands are linked to the same .ttf which is included next to python script. Also it is not because of Docker, when I try Docker Ubuntu container, the result is ok (same as non-docker above):

Unfortunately I have to use an Alpine Docker container. Do someone know how to fix it?

Finally when I have compiled an older version of freetype (2.4.1 from https://github.com/LuaDist/freetype), the output is fine (image from Ubuntu = image from Alpine)

git clone https://github.com/LuaDist/freetype
cd freetype
./autogen.sh
./configure
make
make install

and after a restart the output from pillow truetype is fine!!