London: The Duchess of Cambridge's first official painting has been unveiled, receiving mixed reviews from critics.
Paul Emsley's work took several months using a technique of building thin layers of oil and glazes on canvas.
The artist had two sittings with the duchess and also worked from a series of photographs he took, the BBC reported.
The portrait is now on display at London's National Portrait Gallery, which commissioned the work. The duchess is the gallery's patron.
Emsley was chosen by the gallery's director, Sandy Nairne. Kate, who studied history of art at St Andrews University, was also involved in the selection process.
The 31-year-old duchess, whose pregnancy was announced by the Royal Family last month, sat for the artist in May 2012 at his studio, and again in June at Kensington Palace.
Emsley said that Kate had expressed a desire to be portrayed as her natural self, rather than her official self.
Originally, Emsley had planned to produce an unsmiling portrait. But on meeting the duchess he changed his mind.
The painting took three-and-a-half months to complete and was presented to the portrait gallery's trustees in November.
Waldemar Januszczak, art critic for the Sunday Times, said he was not impressed by the painting.
He said that he was disappointed, as he was waiting for it, like everybody else, with great expectation.
He thinks she's been let down really by the picture.
When Emsley was asked how he felt about some art critics' less than flattering comments about his work, he said he tried his best, and understands that it's not to everyone's taste.
However, Alastair Adams, president of the Royal Society of Portrait Painters, said Emsley had showed the natural, not official, side of the duchess.
He said it's quite natural, open, straightforward and very pure, adding that it's "immediate and not overly sentimental."