pHash - https://www.phash.org
apk update
apk add build-base cmake git autoconf automake libtool
apk add cimg libpng-dev libjpeg-turbo-dev tiff-dev
cmake .
libtoolize --force
aclocal
autoheader
autoconf
automake --add-missing
./configure --enable-video-hash=no --enable-audio-hash=no
make && make install