Given the following context:

In late 1833 Etty was commissioned by Williams-Wynn to paint a portrait of two of his seven children. Preparing for a Fancy Dress Ball depicts Williams-Wynn's daughters Charlotte and Mary, dressing up in lavish Italian-style costume. Although their dress is generally described as Italian, Dennis Farr's 1958 biography of Etty speculates that elements of the costumes were possibly intended to be Russian, based on Charlotte's headdress. The Italian-style clothing likely represents the high level of interest in Italian culture in early 19th-century England. The popularity of the style of music now known as bel canto, widely associated with Italy, was at its peak; likewise, the Italian plays of William Shakespeare had become extremely popular in the period. Etty, who had spent a good deal of time in Venice and other Italian cities, would have been very familiar with Italian clothing designs, and the costumes worn by the Williams-Wynn sisters closely resemble those of women in Venetian scenes painted by Etty, such as 1831's Window in Venice, During a Fiesta. As art historian Leonard Robinson points out, despite the title the sisters are not in fact shown preparing for the ball, but are fully dressed. The style of the work reflects that of Thomas Lawrence, who had been Etty's teacher in 1807–08, as well as that of Joshua Reynolds, of whom Etty was a great admirer and of whose works Etty had often made copies as an exercise.

answer the following question:

What is the last name of the person who painted Window in Venice? 

Etty