Digital Manipulation: An Easy Ethical Rating Scale

Written by Devon Meadows.

I would consider digital manipulation, or photo manipulation, one of the world’s greatest tools.  As we look into the realm of photo manipulation as a whole, we will explore some of the mathematical qualities found in these photos and how scientists have interpreted them on a rating scale.

What does the world think of photo manipulation? Throughout the decades, editors and photo retouchers have been highly criticized for their skills in photo retouching. This “technical retouching” is the type of enhancement used to adjust colors, remove flaws, and alter the image in a small way to make big differences.  It is understood that editing an image to a certain degree is not always appropriate or ethical. We must look at the reasoning behind the edit.  Is the edit in the subject’s best interest? Does the photo’s manipulation drive the theme of the image in a way that is not ethical? The answers to these questions are variable to the project. Many countries have taken a look at these variables and have passed laws regulating them.  The United Kingdom does not allow retouched photos that have been enhanced beyond such regulations.  The reasoning behind this is that some images, mainly overly retouched celebrity photos, can cause self esteem problems and even eating disorders among their audience. This is a major problem in our society today.

Now, is there any math or geometric relevance to the way photos are retouched?  Most definitely! In a study done by Eric Kee and Hany Farid of the Department of Computer Science at Dartmouth College, researchers found that there can be a scale applied to photos that determines their rating by looking at the qualities in which a person’s appearance has been digitally altered.

The method they use requires for them to have an original copy of the photo as well as the altered copy. According to the study, “[they] have developed a metric that quantifies the perceptual impact of geometric and photometric modifications by modeling common photo retouching techniques.” Before we dive into the details of how these photos are analyzed and rated, we must first look at some key terms to understand.

Geometric distortion is a scientific term that basically describes the effects rendered by the liquefy filter found in Photoshop.  The more an image is altered by being either squeezed, “fisheyed”, or pushed around, the higher the rating is for that section. Some examples of geometric distortion would be the slimming of legs, hips, and arms, the enlarging of eyes, and the pulling of neck to improve posture.

Photometric distortion is a term not defined in any online source available. Many photo correction solutions use this term to define changes made to the photo that affect other qualities outside the geometric area.  Some examples of this would be changes made to the texture of skin or applying sharpening/softening to the subject.  The clone stamp and healing brush seem to be the most common photometric distortion tools.

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Shown in order from left to right are an original photo and a modified photo.  The three pictures following are an analysis of the geometric and photometric qualities they have. In photo three there is a vector field measuring geometric qualities most likely done with a “liquefy” effect.  Photo four is a breakdown of sharpness and blurring, with positive values signifying blurring and negative values indicating sharpness. The final photo shows how much photometric distortion may have been used with a tool like the clone stamp.


If you would like to learn more about this study and how these values can be taken even further to determine the photo’s overall percentage of manipulation, please read this full study HERE.


What are your thoughts on digital manipulation? Do we need to regulate it to this degree? Is there anything ethically wrong with the above photo touchups?

Video by BMoreStyles.