Lenna or Lena is the name given to a 512×512 pixel standard test image which has been in use since 1973, and was originally cropped from the centerfold of November 1972 issue of Playboy magazine. It is a picture of Lena Söderberg, a Swedish model, shot by photographer Dwight Hooker. The image is probably the most widely used test image for all sorts of image processing algorithms (such as compression and denoising) and related scientific publications.
The anglicised version "Lenna" of Lena Söderberg's actual name comes from the Playboy article where Playboy changed the original "Lena".