Artistic innovation matters when a painting introduces a new way of using colour, light, space, technique or composition.
Historical importance grows when a work is connected with a major period, patron, belief, event or change in society.
Museum visibility gives a painting a stable public setting, expert documentation and repeated exposure to large audiences.
Influence becomes clear when later artists, movements or visual culture respond to the work or build on its ideas.
Cultural recognition expands through books, education, film, advertising, digital media and repeated public reproduction.
A memorable visual identity, unusual history, controversy, theft or unresolved interpretation can make a work easier to recognise and discuss.