kwin-effect-grayscale (Project dead as of 2020)

Turn the entire screen or a window in grayscale

Shortcuts

CTRL + META + G for grayscaling the entire screen

CTRL + META + H for grayscaling the current window

You can change the shortcuts via System Settings -> Global Keyboard Shortcuts -> KWin

Or directly from the kwin effects settings menu

Installation

ArchLinux: AUR

Manual build

You need extra-cmake-modules, kwin and kf5 *-dev packages installed

git clone https://github.com/ugjka/kwin-effect-grayscale.git
cd kwin-effect-grayscale
mkdir build && cd build
cmake .. \
        -DCMAKE_C_FLAGS:STRING="" \
        -DCMAKE_CXX_FLAGS:STRING="" \
        -DCMAKE_EXE_LINKER_FLAGS:STRING="" \
        -DCMAKE_SHARED_LINKER_FLAGS:STRING="" \
        -DCMAKE_INSTALL_PREFIX=/usr \
        -DCMAKE_INSTALL_LIBDIR=lib
make
sudo make install

TODO

add gamma correction feature