path: root/README.md

**Request for contribution:**

If anyone have a monitor with backlight
supported by xbacklight. src/blueshift_randr_c.c
needs to be extended to be able to read and set
backlight settings. src/blueshift_idcrtc.c can
be used as a starting point of the implementation.

---

Blueshift
---------

Inspired by Redshift, Blueshift adjusts the colour
temperature of your monitor according to brightness
outside to reduce eye strain and make it easier to
fall asleep when going to bed. It can also be used
to increase the colour temperature and make the
monitor bluer, this helps you focus on your work.

Blueshift is not user friendly and it is not meant
to be, although its user friendlyness is increasing.
Blueshift does offer limited use of command line
options to apply settings, but it is really meant
for you to have configuration files (written in
Python 3) where all the policies are implemented,
Blueshift is only meant to provide the mechanism for
modifying the colour curves.

Blueshift neither provides any means of automatically
getting your geographical location; the intention is
that you should implement that in the policy yourself
using library which can do that. Additionally Blueshift
provides not safe guards from making your screen
unreadable or otherwise miscoloured; and Blueshift will
never, officially, add support specifically for any
proprietary operating system. Blueshift is fully
extensible so it is possible to make extensions that
make it usable under unsupported systems, the base code
is written in Python 3 without calls to any system
dependent functions (with exception for fallbacks.)
This is not necessarily true for configuration script
examples and optional features.

If Blueshift does not work for you for any of these
reasons, you should take a look at Redshift. The mean
reason for using Blueshift over Redshift is to add
adjustments that they implemented in Redshift or
using very customised behaviour, such as the example
configurations scripts sleepmode, xmobar and xmonad.

Unique features
---------------

- Blueshift can cancel out effects of sigmoid curves.
This type of calibration is very difficult to get right
but is required to perfectly calibrate LCD monitors.

- Blueshift is not limited to curve operations over sRGB,
but have also support for curve operations over linear
RGB and CIE xyY. This is useful for example for more
accurate brightness modifying filters.

These two types of calibrations can be built in to lookup
tables, which ICC profiles normally uses, in other software
if it is done manually.

- (Currently being implement) Blueshift can modify the
colour curves for monitors without a display server like
X or Wayland. This is done by using Direct Rendering Manager.


Installing
----------

#### Manually

    make PREFIX=/usr/local LIBEXEC=/libexec/blueshift
    sudo make PREFIX=/usr/local LIBEXEC=/libexec/blueshift install
    sudo install-info /usr/local/share/info/{blueshift.info,dir}

See `DEPENDENCIES` for dependencies, and `Makefile` for
additional installation options.

On error make sure you do not have `--as-needed` in `LDFLAGS`.

#### Arch Linux

Blueshift is available in the Arch User Repository,
under the name `blueshift`.