An Essay on Digital Image Manipulation

by

Chuck Doswell


Posted: 05 May 2008 Updated: 01 october 2012: added a discussion of HDR image manipulation

This page had been posted on my Outdoor Images site, but was inadvertently omitted when changing to a new domain host. My profound thanks to Elke Edwards, without whom this essay would not have been possible to restore.

NOTICE: All images are copyrighted! The and the contents of this essay are not to be used without my expressed permission. Contact me at cdoswell@earthlink.net for information about use of these images. Any unauthorized use is a violation of federal and international copyright law, and will be treated as such if I find out about it!


Introduction

With the development of digital imagery, first by scanning film images and then directly from digital cameras, a whole new world of possibilities has opened up for photographers. In the days of film, image manipulation beyond the simple press of the shutter has been the province of those who were able to do (a) development and (b) printing of images. For the world of black and white (b&w) photography, this was certainly within reach of many serious photographers - b&w film processing is relatively easy and darkroom equipment for b&w prints is not terribly expensive. Color, on the other hand, was another matter. Color emulsions are much more temperature sensitive than their b&w counterparts, and color printing is overall much more expensive than b&w.  Once I made the switch from b&w to color transparency films, my developing and printing days were over. I just never wanted to invest all that time and money, so I've used retail color labs for processing and my occasional forays into making prints from my slides. Or at least up until recently, when I converted wholly to digital photography. I still have my transparencies (and some negatives) but I touch them only rarely, now, and then only to scan them for use as digital images.

Anyway, for full-time professional photographers using film, the amount of creative control associated with being able to do your own processing and printing offered a huge advantage for those who could afford the time and expense. Average or even rather poorly exposed negatives could still be manipulated in the darkroom to give acceptable results, and a mediocre negative could still be used to make good prints. The late Ansel Adams was a master of just this sort of manipulation, and tells the story of how the process worked in his book, The Making of 40 Photographs. His description therein of what it took to get what he considered a useable negative and an acceptable print of "Moonrise Over Hernandez, NM" is fascinating, given that this stupendous image is arguably one of the best photographs in the 20th century!

By various methods, darkroom masters could overcome many obstacles to creating the perfect image, including "spotting" the negatives and prints to eliminate the effects of dust and scratches, bringing out detail in shadow and highlight areas by "burning and dodging", and even removing unwanted items from the shot (facial blemishes in portraits, etc.). These and many more "tricks of the trade" were considered essential in obtaining pleasing results.

And of course, there were other "tricks of the trade" used during the shooting to obtain results in situations where the medium (the combination of camera and film) might not always yield good results. These include such things as polarizing filters, graduated filters, flash fill or reflectors, special film emulsions, various kinds of tinted filters, multiple exposures, and so on. The late Galen Rowell (see his book Mountain Light) was another master of the craft needed to achieve memorable images of the natural world using film. By the way, he also was worried about the loss of credibility associated with digital image manipulation.

As if that weren't enough, it was possible to create "composite" images by such tricks as printing multiple negatives, double exposing the print. This would result in images that while wholly photographic in creation, could be of scenes that are wholly imaginary.

Limitations of the photographic medium

All of these have been regularly accepted tools of the photographic trade for many years. Essentially, photography is a very limited medium - not only is the photographer limited to the light at his/her disposal, but the system of camera and lens plus film and print emulsions has severe limitations on what can be done photographically in comparison to what the eye can see. Many photographer's tricks were developed to overcome, at least in part, the limitations of the photographic system for capturing what the photographer can see, or imagine.

Since I've mentioned imagination, the photographer exercises considerable creative control of an image by how the image is composed before it is photographed. Distracting aspects of a photograph can be selectively excluded from an image before the shutter is pressed by changing the viewing angle, exposure, and lens focal length. Distracting elements can be mitigated by selective focus and other techniques involving a knowledge of the reciprocity relationship (see here for a discussion). The negative can be cropped in printing to enhance the composition still further.

Of course, the photographer virtually by definition is limited by the medium in the sense that objects subjected to photographic image creation must be real objects. This is quite unlike the complete freedom enjoyed by a painter, who can create a world in almost any way conceivable, a photographer's world must obey the laws of physics. At least up until now, in the digital age.

Photography and "Truth"

The relationship between photography and "truth" has been an important hallmark of photographic images - no one would be likely to use what appeared in a painting as evidence of something in a court case, for example. Since the painter is free to put anything into his/her painting in any way that suits her/his fancy, a painting could not be considered credible evidence of anything except the artist's imagination. On the other hand, court cases can be and have been decided on the basis of photographic "evidence" because it was argued that "the camera does not lie".

I've already suggested that there have been many ways to get a camera to "lie" in the sense that some parts of a photographic image can be manipulated. It's been assumed in many cases that such manipulations ought to be readily detectable, but in fact some of them might not be detected easily. The notion of photographic "truth" has always been subject to a number of caveats, but in general, really sophisticated photographic manipulation has been limited to a small number of people who possess the tools to do it well enough to be able to fool a discerning eye. The layperson might have trouble detecting subtle manipulations of a photographic image, but a professional would be much more difficult to fool. Difficult to fool, yes; but is it impossible to fool a pro? Not at all!

The whole notion of photographic "truth" has been on a slippery slope toward being discredited for some time, as image manipulation tools have become more sophisticated, but in my opinion, the concept of such truth has always been on dubious foundations. For example, as discussed elsewhere, the notion of "true" color is at best an abstract goal that likely could never be achieved or verified. It's possible for photographic images to represent some semblance of "truth" in a very limited sense:  if someone was standing next to the photographer at the time the shutter was pressed, it would be possible for that person to verify that at least the major elements of the image were as depicted in the photograph at the instant of image capture. Unless the witness had a "photographic" memory, it's always possible that minor elements of the image could have been changed by the photographer and the witness simply wouldn't remember those elements in sufficient detail to verify their credibility, especially the actual colors as perceived at the time.

I'm certain that photographs taken by law enforcement must meet certain standards before they're considered admissible as evidence in court, but I don't know enough about such things to know the details. Nevertheless, photographs from crime scenes are often introduced as evidence, so there must be some basis and rules for accepting them as truthful representations of the subject matter.

It's clear that the cinema industry and advertisers have been leaders in image manipulation for decades, using the medium of film literally to create new worlds by "fooling" the camera and, hence, our eyes. The level of sophistication of such manipulation has grown to astonishing proportions, and now it's commonplace to accept without much comment images that are literally extra-ordinary. This can also done for the sake of art, of course, as well as for catching a customer's eye, but the tricks of the trade in cinema and advertising were well on their way to high sophistication well before the advent of the digital image manipulation era. Digital creations are now accepted as commonplace and they're difficult for the non-expert to identify. Thus, the handwriting has been on the wall for some time. But until the digital explosion, as noted already, these tricks were mostly the province of those with the technical expertise and resources to do them, and it was always a fairly small number of such experts.

Impact of digital image manipulation

With the development of digital imagery, two things have happened. First of all, reasonably sophisticated image manipulation that was formerly the territory of a select few has come within the reach of anyone who can afford a personal computer and some software. PhotoShop™ is the industry standard for still image manipulation, and it's a very sophisticated tool. I don't pretend to understand all its features, but my limited knowledge has put a whole range of tricks at my disposal that were formerly unavailable to me.

Second, the scope of image manipulation has been increased to levels far beyond what was done with film alone. Things have reached the point where whole films can be created digitally that come close to photographic reality and yet exist only as digital images. Worlds can be created that need not obey any natural physical laws and creative control has grown to where it's hard to imagine any serious limits to what the future has in store for digital images. Things can be "shown" that never were and could never be with a "photographic" clarity that would easily fool even an expert eye. This will have the ultimate impact of making a digital "photograph" as unreliable for evidence of "truth" as an artist's painting! We're close to that now, I believe.

Of particular interest for me as I look around the Web and elsewhere, I find numerous examples of faked tornado images, where PhotoShop™ (or some comparable software) tools have been used either literally to draw in a fake tornado or to paste in a tornado from some other image. In the past, faked tornado images were pretty easy for me to recognize, although a few are done more skillfully than most. Given that non-faked tornado images are difficult to come by, I tend to be concerned when I find that potential clients have bought such fake tornadoes for book covers, calendars, and such. It's true that image manipulation in some form or another has been part of photography virtually from the outset of the craft. However, this sort of cheating has stepped over the boundary of "truth" that I described above. It fails the test of the witness standing next to the photographer at the moment of pressing the shutter, since no tornado (surely something that a witness would be able to see and remember!) was present in the scene at the time.

I know of numerous examples of such fakes, but I suspect I would have to deal with lawsuits if I actually presented them as examples here. Instead, I offer some examples I myself have created. One is a rather crude use of the drawing tools and the other has been creating by pasting a tornado from another photograph into a cloud image.

This is a crudely-faked tornado, superimposed on a real cloud photograph. It was done with a black brush tool simply by drawing right over the original. It's so crude, it's obviously a fake. Amazingly, even crude fakes as primitive and obvious as this one have been used for book covers, mouse pads, and so on by nave clients.

A somewhat more sophisticated fake follows:

Composite mage 2003 C. Doswell

I created this fake, composite image by combining the following original image:

with the following original real tornado photograph.

The preceding is my first-ever (and only) attempt at a fake tornado composite. With practice, I assume I could get better at this. To do this one, I pasted a size-adjusted cutout of the real tornado into a layer on top of the original photograph, after flipping the tornado image over to get the highlight on the left instead of the right, matching the direction of the light in the original image of the cloud. Then I adjusted the color until it more or less matched the background, and then used the cloning tool to blend the background with the tornado. When the layers were flattened - presto - a tornado where none had been. It took about 20 minutes to complete. I think it's not too bad for a first effort and it suggests what's possible.

This image not only shows a real storm, but it's a storm that actually could have produced a tornado similar to the fake and the fake is in more or less the location where a real tornado might have been produced. I could use the image to fool some unsophisticated storm chasers, to say nothing of the general public and clients looking for dramatic tornado images.

A somewhat less egregious form of manipulation, in my opinion, is the removal of elements from an image. As an outdoor photographer, the proliferation of power lines causes me considerable difficulty in trying to keep them out of most of my images. When I first started outdoor photography, the very ubiquity of power lines made it easy for me to overlook them, because my brain literally filtered them from my sight. I simply did not see them, even though I was looking through them. When I got the images back from processing, however, I was able to see them clearly, because the photographic system has no such filter within it. Here's an example where the wires create an obvious distraction from the subject. I became very conscious of the presence of wires after a few years of returning with such shots.

Image 2003 C. Doswell (original image from 1982)

[Remember, we see with our brains, not our eyes, because the eyes are only sensors that convert incoming information into "signals" for processing by our brains.] Sometimes, power lines are acceptable and perhaps even visually interesting, but mostly I find them a distracting element. It's especially easy to not see them when shooting lightning at night. If they can be removed from an image without it being obvious, then I feel relatively comfortable doing so, although this is close to the borderline of acceptability for me. Here's an example with and without power lines, in a shot where I didn't recognize they were even there until well after the shot, when the slides came back ...

Image 1984 C. Doswell

Using the cloning tool, it was relatively easy to remove them from the image in a way that appears to be nearly undetectable:

Image 2003 C. Doswell

It's obvious to me that the lines are a distraction and the image is clearly better without them, unless of course one is interested in images with powerlines!
 

Photography as art

If we get into the question of photography as an art form, then the range of acceptable manipulations expands without limit, it seems to me. A "photographic" image that has been manipulated in some way to accomplish what an artist can imagine isn't particularly bothersome to me.  Using the medium to create unreal images is something that I might consider trying someday, but I have no compelling need to do so. In my current creative vision, such things are forbidden, not by principle but by personal choice. I like having the ability to say, when people respond to my images, that had they been there at the time and place when the image was shot, that they would have been able to see what my image shows. For me, photography's artistic side is tied to the use of a limited medium. If the medium weren't limited, photography wouldn't be anywhere near so interesting. The challenge is often to overcome those limitations and try to get the image to reveal what I could see with my eyes. despite the limitations of photography. This requires craftsmanship and the ability to recognize ways around the medium's limitations. As noted here, human vision has a much greater dynamic range than any camera/film/print system. A lot of effort is necessary to capture those magic moments that I'm fortunate enough to see when doing my outdoor photography. Thus, if I were to manipulate my images to put in things that weren't there when the image was shot, I might get some memorable images from that process, but I'd lose the capability to convey my feelings about such moments through a more or less "truthful" medium. Most of my photographs say "I was glad to be there because here's a wonderful scene that I saw.   I hope you can imagine something of what I felt at the time." If they only said something about a completely imaginary moment, then my images would have a reduced impact, as I view things.

If someone else wants to express their imagination by doing unlimited photographic manipulation, that's only slightly different from what painters have been able to do for centuries. Although I have no reason to dispute their right to do this sort of art, at present it's not something that I want to do. It's similar to the choice a painter makes in choosing between, say, the "Realist" and "Abstract" schools of art. I actually like some abstract art, but I choose not to follow that line in my own photography. If some of my photographs reveal special moments when light and subject combine to offer an image that approaches an abstraction, then so much the better for what I'm trying to accomplish. But I'd never so manipulate a photographic image to the extent that someone standing next to me at the time of pressing the shutter would not have seen what the image shows.

And I resent the fact that some image creators sometimes offer clients an imaginary event as if it were real, in the sense I've described. I'd have no problem if they admit that their tornado image is a fake, but to say nothing about it is equivalent to claiming it's real - in effect, it's a form of fraud. If the client is interested in an imaginary tornado shot because it suits their need, that's fine, so long as the client knows it's a fake.

High Dynamic Range (HDR) image manipulation

The advent of digital imaging has added a new tool to the toolkit of photographers. With ordinary image manipulation tools, it's possible to alter the color balance, brightness, contrast, and saturation of images. These simple image manipulations can be overdone, especially the contrast and saturation, to produce images that look "overprocessed" to my eye.  It's tempting to do so and, in my opinion, can be done so as to reproduce what the eye can see, with its higher dynamic range than any camera system.

Here are three images illustrating what can be done using "Bridge" in PhotoShop.  The first is more or less an unmodified image ... all that was done was to clear up some vignetting in the corners.




Next is what I was able to do to compensate for the contrast issues using Bridge.  I was able to bring out some of the details in the foreground and elsewhere in a realistic way, as well as modify the color slightly to make it less "muddy" than the original image.



Finally, here's my version of an "overdone" image - a modification of the second version to brighten it, as well as to increase the contrast and saturation (excessively - in my opinion).  I believe the second image (above) is closest to what my eye could see at the time.  This artificial look seems to dominate many images I see posted in Facebook these days.  This is all the rage, it seems, and is supposed to be what sells.



Some HDR images I've seen are far more obviously manipulated than these!  With time, the demand to do something about the limitations of the dynamic range of the photographic system stimulated the development of HDR software for digital images. By way of an abbreviated explanation, the dynamic range of the system is associated with the contrast in the scene. If the dark areas are very dark compared to the bright areas, the darks come out totally black (sometimes called "blocked up") and the bright areas come out totally white (sometimes called "washed out"). Some high-contrast scenes simply can't be captured with a single photograph for that reason.  For cameras using film as the recording medium, the emulsions used on the film were the primary limitation on dynamic range -- some slide films had very limited range (only a few f-stops) when compared to what the eye could see. With the advent of digital cameras, HDR processing has become common.  The camera is used to "bracket" the exposures so that the combined images using HDR have neither blocked-up shadows nor washed-out bright areas. 

Unfortunately, some people who use HDR do so in a way that looks faked.  I'm not doing HDR right now and I don't wish to post images from other people here, but many will know what I mean.  I have no problem with using HDR to overcome some of the camera system's inability to handle the dynamic range we can see with our eyes.  But many HDR users overdo what the system allows them to do, such that if you were standing next to the photographer as the images were shot, you wouldn't see what the final image shows.  This, of course, is a purely personal opinion, and anyone who wants to dispute this opinion is free to think and do whatever they wish.  In principle, I have no objection to HDR, provided the process is not so overdone the image no longer corresponds to what a human standing next to the photographer would have seen.

Concluding thoughts

As photographers, we all make choices about the level of creative control we feel is acceptable when using the photographic medium. True "purity" in an image is an abstract ideal that's difficult even to imagine.  To be truly "pure," all photographic manipulations would have to be avoided: no filters, no flash, no push/pull processing, no choice of film emulsion, no spotting and retouching, no composition, no cropping, no filters, no lenses other than "normal" lenses, etc. This ideal would result in photographs that would be comparable to what we regard as snapshots by the lowest ranks of amateur photographers.  Hence, I'm not in favor of "purity" and I don't even consider it a particularly desirable goal.

The ability of serious amateurs and professionals to produce stunning images using a limited medium is at the very heart of what makes them serious photographers. But when image manipulation allows the production of images of things that aren't real and may not even be physically possible, then that sort of image needs to be identified clearly as something distinctly different from images that purport to have recorded an actual subject in the real world.

Recently, I was engaged in a discussion of an image where it seems the photographer recorded two images from the same scene. One was exposed for the highlights of the scene and the other was exposed for the shadow areas.The scene was one of such contrast that no known film emulsion or digital sensor could have captured the scene as a human would have seen it. The photograher then pasted the properly exposed highlights, framed in a window, into the scene exposed for the shadows. This is a film version of HDR image processing.  Although this is a "composite" image, I have no substantial objection to such an image. In fact, I think it was a creative solution to a problem I've encountered myself on many occasions. Sometimes, the use of graduated filters permits me to overcome the challenge of too much contrast in a scene, but in the case in question, such filters would not have worked. The approach of using two separate exposures and then combining them allows the image to reveal what a person at the scene would have actually been able to see. Thus, it passes my "truth" criterion rather easily. Although any such criterion can be pushed toward more ambiguous interpretations, this particular "composite" image is not something that would need to be labeled as a composite, in my opinion. Rather, I see it as just another creative solution to the limitations of the medium.

Therefore, the impact of digital image manipulation is, like virtually all innovations, a two-edged sword. It permits exciting new ways to achieve desired results, but it can be abused to blur the distinction between truth and falsehood, reducing the credibility of photographic images as representations of reality. This conflict will only grow more challenging as the capability of digital image manipulation expands

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