Lenna or Lena is the name given to a standard test image which has been in use since 1973. It comprises 512×512 pixels, 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".
Before Lenna, the first use of a Playboy magazine image to illustrate image processing algorithms was in 1961. Lawrence G. Roberts used two cropped 6-bit grayscale facsimile scanned images from Playboy's July 1960 issue featuring Playmate Teddi Smith (born Delilah Henry), with attribution, in his MIT master's thesis on image dithering.
Intended for high resolution color image processing study, the Lenna picture's history was described in the May 2001 newsletter of the IEEE Professional Communication Society, in an article by Jamie Hutchinson:
Alexander Sawchuk estimates that it was in June or July of 1973 when he, then an assistant professor of electrical engineering at the University of Southern California Signal and Image Processing Institute (SIPI), along with a graduate student and the SIPI lab manager, was hurriedly searching the lab for a good image to scan for a colleague's conference paper. They got tired of their stock of usual test images, dull stuff dating back to television standards work in the early 1960s. They wanted something glossy to ensure good output dynamic range, and they wanted a human face. Just then, somebody happened to walk in with a recent issue of Playboy.
The engineers tore away the top third of the centerfold so they could wrap it around the drum of their Muirhead wirephoto scanner, which they had outfitted with analog-to-digital converters (one each for the red, green, and blue channels) and a Hewlett Packard 2100 minicomputer. The Muirhead had a fixed resolution of 100 lines per inch and the engineers wanted a 512×512 image, so they limited the scan to the top 5.12 inches of the picture, effectively cropping it at the subject's shoulders.
This scan, cropped as it was, became one of the most used images in computer history. A single issue of IEEE Transactions on Image Processing, Volume 8, Number 4, April 1999, used "Lena" as an example in three separate articles (pp. 559-60, 569-70, 591). The mysterious Lenna came to be dubbed, according to a 1997 Playboy article, the "First Lady of the Internet". Hutchinson wrote in 2001, "Even today, if you thumb through an issue of Optical Engineering or a related journal, you are likely to see more than one Lena, and sometimes dozens of her."
First, the image contains a nice mixture of detail, flat regions, shading, and texture that do a good job of testing various image processing algorithms. It is a good test image! Second, the Lena image is a picture of an attractive woman. It is not surprising that the (mostly male) image processing research community gravitated toward an image that they found attractive.
Lenna is so widely accepted in the image processing community that Söderberg was a guest at the 50th annual Conference of the Society for Imaging Science and Technology (IS&T) in 1997. The use of the photo in electronic imaging has been described as "clearly one of the most important events in [its] history".
The use of the image has produced some controversy, with some people concerned about Playboy magazine as the source of the image, and with the image being copyrighted, though Playboy in 1997 indicated less interest in copyright, and more in the image as "a phenomenon." Others have pointed to the Lenna photo as an example of sexism in the sciences, reinforcing gender stereotypes. A 2012 paper on compressed sensing by Deanna Needell and Rachel Ward uses a photo of the model Fabio Lanzoni as a test image to draw attention to this issue.
In a 1999 essay on reasons for the male predominance in computer science, Dianne O'Leary wrote:
If a professor makes a sexist joke, a female student might well find it so disturbing that she is unable to listen to the rest of the lecture. Suggestive pictures used in lectures on image processing are similarly distracting to the women listeners and convey the message that the lecturer caters to the males only. For example, it is amazing that the "Lena" pin-up image is still used as an example in courses and published as a test image in journals today.
Playboy helped track down the Swedish native in Stockholm, where she helps handicapped people work on (non-networked) computers. Although Playboy is notorious for cracking down on illegal uses of its images, it has decided to overlook the widespread distribution of this particular centerfold.
Says Eileen Kent, VP of new media at Playboy: "We decided we should exploit this, because it is a phenomenon."
Coincidentally, Playboy states the issue (November 1972) was its best-selling ever, having sold 7,161,561 copies as of May 2006, and the Lenna centerfold appears briefly in Woody Allen's film Sleeper released the following year.
- "Playboy centrefold photo shrunk to width of human hair". BBC News Online. 14 August 2012. Retrieved 15 August 2012.
- Roberts, Lawrence G (1961). "Picture Coding Using Pseudo-Random Noise". MIT.
- Hutchison, Jamie (May/June 2001). "Culture, Communication, and an Information Age Madonna" (PDF). IEEE Professional Communication Society Newsletter (archive) 45 (3).
- "The Search for Lena: Discovering one Playmate's role in the history of the Internet". Newsdesk. Playboy Enterprises, Inc. 1997. Archived from the original on July 4, 1997. Retrieved December 20, 2012.
- O'Leary, Dianne (June 25, 1999). "References: But the instructor's attitude can't make the female student fail, can it?". Retrieved October 25, 2013.
- Munson, David C, Jr (January 1996). "A Note on Lena". IEEE Transactions on Image Processing (archive) 5 (1).
- Rosenberg, Chuck (November 3, 2001). "The Lenna Story: Imaging Experts Meet Lenna in Person". CMU.edu.
- Zax, David (16 August 2012). "A Playboy Model and Nanoscale Printing". MIT Technology Review. Retrieved 24 September 2013.
- Brown, Janelle (May 20, 1997). "Playmate Meets Geeks Who Made Her a Net Star". Wired News.
- Needell, Deanna; Ward, Rachel (February 29, 2012 (v1)). "Stable image reconstruction using total variation minimization". Cornell University Library / Arxiv.org.
- Carron, Igor (March 9, 2012). "I can't believe it's not Lena". Nuit Blanche. blogspot.com.
- O'Leary, Dianne P (June 25, 1999). "But the instructor's attitude can't make the female student fail, can it?". Accessibility of Computer Science: A Reflection for Faculty Members. University of Maryland - Department of Computer Science. Retrieved October 26, 2013. (References list.)
- "The Playboy FAQ: What is Playboy's circulation?". Playboy Online. Archived from the original on May 24, 2011.
- "Lenna 97: A Complete Story of Lenna". Dr. Lai Man P web pages. City University of Hong Kong. 28 July 1997. Retrieved 24 September 2013.
- "The photo of Lena Söderberg". computableminds.com. 29 April 2012. Retrieved 24 September 2013.
- Lenna 97: A Complete Story of Lenna
- The Lenna Story - Contains a link to an un-cropped scan of the original Playboy photograph