The moment a photojournalist releases the shutter a sacred threshold is crossed. The instant after the shutter blinks open and closes, whether it is for a thousandth-of-a-second to freeze the impact of a baseball bat on a ball, or several hours to soak up the faint glow of a passing comet, the door also shuts for a photojournalist to manipulate that captured representation of reality. Any technical choices made before that moment - whether a choice of cameras, light, lenses, filters, exposure settings, or simply where to stand - are generally accepted as tools for achieving the photographer's vision. Any digital post-processing beyond the accepted darkroom techniques of yore, such as burning or dodging, are usually considered a prohibited manipulation of that sacrosanct moment of exposure.

Adobe PhotoShop is an ingenious, powerful, and insidiously seductive tool, offering total control of a photograph down to the subatomic level of individual pixels. We have all heard the career-ending horror stories about photojournalists who have used this dynamic tool to flagrantly alter their photographs. Others may just fudge the line a little as they attempt to enhance their images. Where does one look for guidance in delineating this murky line between vision and manipulation? The career of W. Eugene Smith casts a cautionary shadow on the subject. Smith, a darkroom wizard whose credo was "Let Truth Be the Prejudice," had no compunction about sandwiching two photos together into one to create his famous Life magazine portrait of Albert Schweitzer. Smith's undeniable passion for his subject left his creative impulses unchecked, and in this case he lost his bearings and strayed grossly over the line.

In light of a discussion about the post-processing of one of the entries in this year's White House News Photographers' Association "Eyes of History 2005" contest, I thought it might be useful to pose a few simple questions:

-When photographing a spectacular sunset, would it be a sacrilege to punch up PhotoShop's Saturation slider in the sky area of a photograph, or is that only legitimate using a polarizing filter before the picture is taken?

-While striving for a different look in documenting a pedestrian presidential campaign rally, would it be grounds for impeachment to use PhotoShop's Gaussian Blur to give an ethereal out-of-focus glow to the crowd of supporters surrounding the candidate, or would that only follow protocol if the photographer chooses to use a toy Holga camera with a gauzy plastic lens?

-In covering a demonstration in the Gaza Strip, is it an outrage to tweak the Levels in PhotoShop so that the protesters appear as graphic silhouettes, or is that only okay if the camera is set to underexpose the scene?

-When photographing a tall building with a wide-angle lens, would a photographer be off-balance if they correct the parallax lines in PhotoShop, or is that modification only permissible when the photograph is taken using the tilt and shift of a view camera?

-If a photojournalist is working behind the scenes on a day-in-the-life-of-the-president story, do they violate their access if they convert their color raw files to grayscale to achieve a grittier documentary look, or should that be banned along with the colorization of old classic black-and-white movies?

-Do news photographers lose their bearing if they crop a vertical photo out of a horizontal composition, or should they adhere to Henri Cartier-Bresson's commandment against cropping? How about using a digital level to correct an inadvertently tilted horizon?

-When a high ISO digital photo is processed through noise reduction software, or when bicubic interpolation is used to increase the file size of an image, is that action innocently correcting for the camera's limitations, or does that subtle transformation of pixels turn an accurate document into a plastic artifact?

-Is a panoramic landscape created in a Widelux camera any more authentic than one digitally stitched together from separate photographs?

-Who is the greater sinner, the legendary New York photographer who decades ago traveled with a teddy bear in his trunk to add some heart-tugging drama to disaster scenes, or the photojournalist in Iraq who combined elements of two photos of a British soldier and Iraqi civilians outside Basra to create a more dramatic composition?

-If a flash creates a demonic red stare in a subject's eyes, is a photographer closer to the truth if they desaturate and darken the pupils, or would that be the work of the devil?

-If a photojournalist forgets to change the white balance from tungsten to daylight should the Photo Police tell them to freeze when they reach for the neutral gray eyedropper?

-Was it wrong or right for old-timers to dramatically darken the corners in the sky area of a photo, using their darkroom skills to create the "Hand of God" look? What if the exact same effect is achieved in camera with a gradient filter? Would a freshly-minted photojournalism student be sanctioned if they accomplished that identical look by using PhotoShop's Lasso, Feather, and Curve tools?

-If a lens has chromatic aberrations, would it be a journalistic aberration to correct the color fringing by dialing in a few numbers in PhotoShop's Hue and Saturation?

-If a photographer has not touched a roll of film in years, would it pass muster for them to use a PhotoShop plug-in to mimic the saturated Velvia look they remember so fondly?

-If a photographer's "vision thing" entails dragging the shutter and popping an off-camera flash at an odd angle to create "eye candy," is that decision any more valid than dipping into PhotoShop's filters menu and applying Motion Blur?

-How about a photographer who uses a very long time exposure of a candlelight march past the White House to create a gossamer river of golden light: charlatan, or journalist with a poetic flair?

-Does a photojournalist lose their inner focus if they use PhotoShop's Unsharp Mask to sharpen past the correction needed to counter the softening affect of a digital camera's anti-aliasing filter? Has the hackneyed photojournalist motto "f8 and Be There!" digitally morphed into "Unsharp Mask and Be There!"?

-Should photojournalists have known that they were all sunk when, at the dawn of the digital photo age, a picture desk jockey did not read the caption carefully and, with a few quick keystrokes, "corrected" the color of a swimming pool that had been dyed red by protesters?

While the answers to these rhetorical questions may be self-evident, it also becomes clear that a photograph can be manipulated easily at any point in the process. A photojournalist must carefully measure their intent, both aesthetic and journalistic, making the choices along the way that lead to clarity and not distortion or superficial showmanship. That intent, ethically calibrated, is the fulcrum that begins to resolve some of these thorny dilemmas, counterbalancing the mantra to create something "different" with the more imperative calling to convey what is true.

The illusion of verisimilitude - the believability of the moment captured - is the rock foundation on which photojournalists stand, even if in reality that rock is made up of infinitely malleable zeros and ones. Ultimately, a photojournalist should strive to temper their desire to produce an image that jumps off the printed page with the debt of honesty owed to the subject, a responsibility due both before and after the inviolable instant the shutter is released.

Perhaps the only advisable way to navigate the slippery slope of digital manipulation is to approach the moment of exposure, not as a sacred threshold but rather as you would a weathered and bullet-riddled road sign that warns: "PROCEED WITH EXTREME CAUTION!"

Finally, for the true ascetics among you who discover in dismay that the dust spot in the sky that you cloned away with a sweet chunk of sky-blue pixels was actually an out-of-focus bird in flight, the absolution for that sin is only one Hail Mary. Just be ready to fire up PhotoShop and get out your digital level, because invariably a "Hail Mary" will have a horizon that is slightly askew.