Among the many temptations of the digital age, photo-manipulation has proved particularly troublesome for science, and scientific journals are beginning to respond.

Some journal editors are considering adopting a test, in use at The Journal of Cell Biology, that could have caught the concocted images of the human embryonic stem cells made by Dr. Hwang Woo Suk.

At The Journal of Cell Biology, the test has revealed extensive manipulation of photos. Since 2002, when the test was put in place, 25 percent of all accepted manuscripts have had one or more illustrations that were manipulated in ways that violate the journal's guidelines, said Michael Rossner of Rockefeller University, the executive editor. The editor of the journal, Ira Mellman of Yale, said that most cases were resolved when the authors provided originals. "In 1 percent of the cases we find authors have engaged in fraud," he said.

The two editors recognized the likelihood that images were being improperly manipulated when the journal required all illustrations to be submitted in digital form. While reformatting illustrations submitted in the wrong format, Dr. Rossner realized that some authors had yielded to the temptation of Photoshop's image-changing tools to misrepresent the original data.