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 Pakistan.  But no one is certain.  In an audiotape that accompanied the footage, a speaker who sounds like bin Laden honors the September 11 hijackers, praises the damage done to "the enemy" on that day, and calls on Iraqi warriors to "bury" U.S. troops.   In other words, the clues are there to indicate that the tape was made some time after America invaded Iraq. 

In a chilling speech, Ayman al-Zawahri, bin Laden's 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 New York and Washington.  Unless the video was staged in some manner, that comment would indicate that the videotape was made close to the time when it was actually broadcast.

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.  It's not a bad idea to do some age-progression anyway, just to see the image of the man we're 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 expression—they 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 it's 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 Quantico (www.karenttaylor.com), provides guidelines for photo-to-photo comparisons.  First, she says, it's important to gather as many photos as possible to assist in the comparison, and second, the imaging specialist must use the best quality photos available.  If the face is at an angle, the specialist will know that the facial shape or some of the features may be distorted.  To guard against mistakes in perception, Taylor suggests that the identification process should "consider the base of the nose in relation to the ears."  It may also help to turn photos upside down to view the features with greater objectivity.  She points out that aging effects do not go backwards, so if one photo appears younger than the one to which it is being compared, either cosmetic surgery has been performed or it was taken at an earlier time.

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.  Taylor notes that there are many electronic programs on the market for performing age progression, and despite the advantages they offer she warns that cautions are in order. 

Her first concern is the quality of the photograph.   If it's 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 can't 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.

"The artist," Taylor points out, "should study and assess each case individually rather than assume that every person will have precisely the same indications of age on the face."   While aging effects—jowls, crow's feet, thinning lips, etc.--tend to occur in a predictable series, they do occur at variable rates for individuals.

In other words, it's 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," Taylor says, "he will age one way versus the way a drug abuser or someone with thyroid condition will age.  Our health is reflected in our faces."  If available, she also likes to have access to photographs of family members—especially older siblings or parents--for inherited aging patterns.

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, Taylor says, should allow for fluid movement and the adjustment of features in all directions, and for change in coloration and scale.  She uses a system that incorporates "draw" or "paint" functions, like Adobe Photoshop, where the artist can use a stylus on a pad to capture subtle nuances in small increments.  It's almost like drawing. 

Yet Taylor emphasizes that people tend to underestimate the difficulty of these processes.  She has noticed a general misconception that computers can miraculously perform transformations on a photograph from one age to another, but these changes actually result from the skill of an experienced and knowledgeable user.  "That person has to know how the face grows and ages, and to understand how facial expressions over time create age lines."

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, it's wiser to work within that schema than to speculate about color—unless 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," Taylor says.  "The bottom line is that the program is not a magic tool.  The computer has to be used within a good knowledge base." 

Yet she adds that there's one stand-out benefit with computer-generated age progression.  "Once the facial image is developed, it's 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.  It's more efficient to do this on the computer."

Back to bin Laden.  If he's out of sight for a significant period of time, the artist can use age progression to help with identification.  If it's 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.

Like Taylor, Neville indicates that the forensic artist is something of an interpreter, even a psychologist: "The artist then takes into consideration all the variables involved with the natural process of aging the human face." He uses programs such as Photoshop, on which he can paint directly onto a digitized photograph, finding ways to use a single image to generate a variety of appearances, influenced by ideas about the choices the fugitive may have made as a means of disguise.   That way, he can alert those who are looking for the fugitive to different possibilities.

In her book, Taylor states that in a cold case the production of an altered image, while an inexact process involving some degree of guesswork, is often "the spark of new life" that can generate sufficient interest to result in closure.  Continuing to artistically age-progress or show possible alternate looks for someone like Osama bin Laden as time passes may become the key to eventually finding him.