Doc improvement and vpImage refactoring #1690

Job	Run time
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 98)	9m 28s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	26m 40s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	29m 1s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 98)	7m 6s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	23m 46s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	26m 12s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 98)	9m 17s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 11)	32m 23s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 17)	34m 15s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 98)	7m 19s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	23m 10s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	26m 11s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 98)	7m 36s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	24m 48s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	27m 52s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 98)	9m 15s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 11)	33m 38s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 17)	36m 31s
	6h 34m 28s

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