I tried 2.4.9 and 3.0.0, both does not contain the actual API documentaions: $ ls /usr/share/doc/opencv-2.4.9/ README.md.bz2 $ ls /usr/share/OpenCV/ OpenCVConfig-version.cmake OpenCVModules-gentoo.cmake doc java samples OpenCVConfig.cmake OpenCVModules.cmake haarcascades lbpcascades $ ls /usr/share/OpenCV/doc/ acircles_pattern.png haartraining.htm opencv-logo-white.png opencv-logo.png opencv-logo2.png opencv.ico pattern.png $ equery f opencv |grep doc /usr/share/OpenCV/doc /usr/share/OpenCV/doc/acircles_pattern.png /usr/share/OpenCV/doc/haartraining.htm /usr/share/OpenCV/doc/opencv-logo-white.png /usr/share/OpenCV/doc/opencv-logo.png /usr/share/OpenCV/doc/opencv-logo2.png /usr/share/OpenCV/doc/opencv.ico /usr/share/OpenCV/doc/pattern.png /usr/share/doc /usr/share/doc/opencv-2.4.9 /usr/share/doc/opencv-2.4.9/README.md.bz2 $ emerge --info: Portage 2.2.18 (python 2.7.9-final-0, default/linux/amd64/13.0/desktop/plasma/systemd, gcc-4.8.4, glibc-2.20-r2, 4.0.5-gentoo x86_64) ================================================================= System uname: Linux-4.0.5-gentoo-x86_64-Intel-R-_Core-TM-_i7-3520M_CPU_@_2.90GHz-with-gentoo-2.2 KiB Mem: 16127524 total, 4611832 free KiB Swap: 0 total, 0 free Timestamp of repository gentoo: Fri, 24 Jul 2015 12:15:01 +0000 sh bash 4.3_p33-r2 ld GNU ld (Gentoo 2.24 p1.4) 2.24 app-shells/bash: 4.3_p33-r2::gentoo dev-java/java-config: 2.2.0::gentoo dev-lang/perl: 5.20.2::gentoo dev-lang/python: 2.7.9-r1::gentoo, 3.3.5-r1::gentoo dev-util/cmake: 3.2.2::gentoo dev-util/pkgconfig: 0.28-r2::gentoo sys-apps/baselayout: 2.2::gentoo sys-apps/openrc: 0.17::gentoo sys-apps/sandbox: 2.6-r1::gentoo sys-devel/autoconf: 2.69::gentoo sys-devel/automake: 1.11.6-r1::gentoo, 1.13.4::gentoo, 1.14.1::gentoo, 1.15::gentoo sys-devel/binutils: 2.24-r3::gentoo sys-devel/gcc: 4.8.4::gentoo sys-devel/gcc-config: 1.7.3::gentoo sys-devel/libtool: 2.4.6::gentoo sys-devel/make: 4.1-r1::gentoo sys-kernel/linux-headers: 3.18::gentoo (virtual/os-headers) sys-libs/glibc: 2.20-r2::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://mirrors.xmu.edu.cn/gentoo-portage priority: -1000 local-crossdev location: /usr/local/portage-crossdev masters: gentoo priority: 0 local location: /usr/local/portage masters: gentoo priority: 1 steam-overlay location: /var/lib/layman/steam-overlay masters: gentoo priority: 2 kde location: /var/lib/layman/kde masters: gentoo priority: 3 haskell location: /var/lib/layman/haskell masters: gentoo priority: 4 ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -pipe -march=corei7" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/config /usr/share/gnupg/qualified.txt /usr/share/maven-bin-3.0/conf" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-O2 -pipe -march=corei7" DISTDIR="/usr/portage/distfiles" EMERGE_DEFAULT_OPTS="--quiet-build=y --jobs=2 --load-average=9 --autounmask-unrestricted-atoms --autounmask-keep-masks --oneshot --nospinner" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-logs config-protect-if-modified distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms splitdebug strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="http://mirrors.xmu.edu.cn/gentoo" LANG="C" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j4" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/var/tmp" USE="X a52 aac acl acpi alsa amd64 apng berkdb bindist bluetooth branding bzip2 cairo cdda cdr cli cracklib crypt cups cxx dbus declarative dri dts dvd dvdr emboss encode exif fam fdk firefox flac fluidsynth fortran gdbm gif glamor gpm gtk gtk2 hoogle iconv ipv6 jack jpeg kde kipi lcms ldap libass libnotify mad mmx mmxext mng modules mp3 mp4 mpeg multilib ncurses nls nptl ogg openal openexr opengl openmp pam pango pcre pdf phonon plasma png policykit ppds python qml qt3support qt4 qt5 readline sdl semantic-desktop session spell sse sse2 ssh ssl startup-notification svg systemd tcpd theora threads tiff truetype udev udisks unicode upower usb vorbis webp widgets wxwidgets x264 xcb xcomposite xinerama xml xscreensaver xv xvid zlib" ABI_X86="64" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="krita" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx mmx mmxext popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3" ELIBC="glibc" ENLIGHTENMENT_MODULES="appmenu backlight battery bluez4 clock conf-applications conf-comp conf-dialogs conf-display conf-interaction conf-intl conf-menus conf-paths conf-performance conf-randr conf-shelves conf-theme conf-wallpaper2 conf-window-manipulation conf-window-remembers connman contact cpufreq everything fileman fileman-opinfo gadman ibar ibox illume2 mixer msgbus music-control notification pager quickaccess shot start syscon systray tasks teamwork temperature tiling winlist wizard xkbswitch access wl-desktop-shell wl-screenshot" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="mouse keyboard evdev joystick synaptics wacom" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LINGUAS="zh zh_CN" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-5" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_3" RUBY_TARGETS="ruby19 ruby20" USERLAND="GNU" VIDEO_CARDS="intel modesetting nvidia" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: CPPFLAGS, CTARGET, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Useflag removal in opencv-2.4.12-r1 and opencv-3.1.0-r4. Other versions will be removed soon.