Computer-Altered Photography: Catching Fugitives
In light of an eight-minute videotape of terrorist Osama bin Laden walking in the mountains, which aired in September 2003, questions arose as to whether or not it was merely an older videotape being passed off as recent to inspire his followers. Some sources say he appears older than a photo taken of him two years earlier, others that he appears younger.
According to the Associated Press, the footage was broadcast by Al-Jazeera television, and was said to have been produced in April or May. This led to speculation that bin Laden is hiding out in
In a chilling speech, Ayman al-Zawahri, bin Ladens chief deputy (or someone who sounds like him) warns, The true epic has not begun. He also mentions the second anniversary of the raids on
So is bin Laden older or younger in this footage than in previous photos? Is there any indication that stress or some injury or illness such as kidney disease is affecting his appearance? One way to analyze the videotape is to compare stills from it to past videos or photos. Another way is to subject past photographs of bin Laden to methods of artistic age progression and compare the results to stills from the current videotape. Its not a bad idea to do some age-progression anyway, just to see the image of the man were still seeking. In addition, coming up with alternate looks may assist in identifying him in the event that he has altered his appearance.
Yet those looks must retain his basic expressionthey must be recognizably him. So the forensic artist working on the renditions must be skilled in photo comparisons and alterations.
Since photography was invented in 1836, it has been a valuable tool for documentation and the sharing of visual information. Law enforcement has relied on photographs in many ways, from mug shots to suspect images, and more recently as the basis for identifications involving age-progression and other computer-generated alterations of missing people and fugitives. The forensic artist has become a facial identification specialist, and many are certified by the International Association for Identification (www.theiai.org). Photo modifications for the purpose of identification can be accomplished in a variety of ways and the artist must consider many factors before deciding which would be most advantageous.
In 1896, Alphonse Bertillon made photo-to-photo comparisons in a book about criminal measurements for identification. He liked to use the ear structure as a basis for identifying the photograph of someone taken at an earlier time to a photo of the person at a later time. That person may have changed considerably in facial features, but the ear generally remained the same.
The identification of a subject from one photo to another, also in use today, relies on a skillful observer and interpreter. The comparison process is not considered a science and it has its limitations, yet positive comparisons can nevertheless assist in the identification of someone long missing. In that regard, computers can be most helpful.
For example, before making comparisons using images of poor quality, such as those available from in-store videocameras, the images may need to be digitally enhanced, and this is often done by an imaging specialist who might be either a photographer or an artist. Then the artist can make a drawing from the enhanced image to use as a basis of comparison, or if its good enough on its own, the enhanced image can be compared on a point-by-point basis to a suspect photo.
Computers can also assist with alternate looks. If one photo of a suspect includes a hat, beard, or glasses, these can be added via computer to another photo of that person to aid in making the comparison.
In her book, Forensic Art and Illustration, Karen T. Taylor, a forensic artist who has taught courses at
Many photo comparisons rely on knowledge of the natural aging process, and another type of computer alteration technique can further educate the identification specialist: age-progressing an outdated photograph. This process was first used during the 1980s for missing children, to assist in retaining their essential features despite the changes produced by growth. It is also used for adults who have been missing for long periods of time, including fugitives on the run.
Her first concern is the quality of the photograph. If its vivid, she says, then using a computer can be a good option. However, if the quality is inferior and cannot be effectively scanned into an imaging system, it cant be subjected to a program for computer manipulation. In that case, a hand-drawn rendition is preferable, using the photo as a point of reference.
I feel that the most significant issue for a forensic artist, she says, is not whether the work is hand-done or computer-generated. The issue is the foundational knowledge that he or she possesses. The successful forensic artist will have an extensive awareness of facial anatomy, including its aging patterns.
In other words, its important to incorporate as much information as possible about the subjects under scrutiny. Their lifestyle factors (such as smoking and exercise), racial ancestry, degree of exposure to the sun, known medical conditions, and other types of information can affect how their faces age. If someone is a health nut,
Once those decisions are made, an important consideration for deciding on a computer program for facial alteration is the quality of the tools offered for image modification. A program,
The critical task is to maintain the look of the person, particularly in the area of the eyes. Also, most people tend to maintain a certain recognizable manner of expression throughout their lives. Former President John F. Kennedy is a good example. One advantage of using computer-generated alterations from photographs is that the baseline expression remains the same throughout the alteration process.
Then there are certain visual decisions to consider, such as with color and angle. If the only available photograph is black-and-white, its wiser to work within that schema than to speculate about colorunless color information is available from verbal descriptions and something like hair color is a distinctive trait. If the face is angled away from the camera, then only certain types of manipulations are possible.
All of this involves training,
Yet she adds that theres one stand-out benefit with computer-generated age progression. Once the facial image is developed, its a simple matter to provide multiple alternate looks without having to draw the whole thing all over again. You can darken the hair, change the hairstyle, or add or subtract things like glasses or facial hair. Its more efficient to do this on the computer.
Back to bin Laden. If hes out of sight for a significant period of time, the artist can use age progression to help with identification. If its suspected that he has changed his appearance to better avoid capture, the artist can alter his look in a number of ways.
Wesley W. Neville, another forensic artist (www.forensicartist.com), offered a computer-altered rendition of Osama bin Laden for Crime Library, showing what the infamous terrorist leader might look like without the beard and headwear. He also provided an alternate appearance for al-Zawahri, removing his facial hair and turban to give him a Westernized look. Neville retained the look of the original photograph that he had used as a basis.
On his Web site, he says, Computer-generated and hand-drawn age-progressions are done for both suspect and victim identification. Yet he points out that the most common use is to apprehend fugitives.
In her book,