A professor with Rice University in the U.S. state of Texas has helped to authenticate a painting by Vincent van Gogh in an Amsterdam museum with digital sleuthing, the university said Thursday. Don H. Johnson, professor of electrical and computer engineering, performed statistical analysis of X-ray images of the canvas behind the previously unknown \"Sunset at Montmajour,\" a painting long believed to be an imitation of Van Gogh, and found it to be his original painting, the university said in a press release. \"When the masters prepared a canvas for painting, they would cut it from the roll, attach it to a stretcher and paint their work. For such a famous artist as Van Gogh, conservators would glue on a backing canvas to preserve the original. Consequently, we can\'t simply take it out of the frame and have a look at the original canvas,\" Johnson said. Don Johnson and Richard Johnson, professor of engineering at Cornell University, have come up with a signal-processing algorithm that automatically counts the thread density in an artist\'s canvas from X-rays, according to the press release. The professors\' forensic investigations reveal previously unavailable details about the masters\' raw materials. An X-ray analysis of the canvas behind \"Sunset at Montmajour\" determined that it matched a similar canvas on a Van Gogh painting called \"The Rocks\" at the Museum of Fine Arts in Houston. Several art experts from the Van Gogh Museum in Amsterdam traveled to Houston to examine the \"The Rocks\" painting. Their judgment, along with the findings from the X-ray analysis, led to the authentication of \"Sunset at Montmajour.\" The Van Gogh Museum unveiled this finding, along with the painting itself, in Amsterdam, the capital city of the Netherlands on Monday. The unsigned \"Sunset at Montmajour\" is privately owned and produced during what the Van Gogh Museum considers to be the artist\'s most productive period, his time in Arles, France in 1888. He died of a self-inflicted gunshot wound in 1890.