A drawing of the head of an old woman bought by an Italian collector in Venice in the 1970s has officially been attributed to Leonardo Da Vinci, a media report said today. The drawing will be unveiled on June 15 at the Doges’ Palace in Venice. The sketch of a head with deformed, monstrous features was sold to industralist Giancarlo Ligabue as being ‘‘in the manner’’ of Da Vinci. ‘‘I bought it from an antique dealer in Venice, who made it very clear I should not delude myself into thinking it was really a drawing by Leonardo,’’ he told Corriere Della Sera newspaper.‘‘A year ago, I published a catalogue of drawings from my collection, and to do this, I asked for help from experts. For the Leonardo-style drawings, I consulted Professor Luisa Cogliati Arano, who is an authority. On this drawing, she said she was puzzled and advised me to have it examined scientifically.’’An infra-red examination showed another drawing underneath the photographic image. ‘‘The examination confirmed that it was indeed by Da Vinci and revealed later additions, common on old drawings. Collectors used to touch up features which they thought didn’t show up enough or even completed details,’’ Cogliati told the paper.