Digital photo manipulation

“A picture is worth a thousand words.”

Although academics should prefer to read a thousand words above just looking at an image to draw conclusions, there might still be some truth in the above mentioned phrase. In most cases, imagery is very powerful to send a message across or convey emotions to the viewer. It is therefore not strange that it has become an essential part of the internet.

Because images are such a vital thing in the digital world, there is also a tendency to alter existing images. In our digital era, this has been made possible due to the emergence of digital image manipulation. Nowadays, anyone who has a computer with image editing software installed on it can go ahead and alter any image that they want.

The practice of digital photo manipulation is not a recent phenomenon. Already in 1982, National Geographic digitally altered a photograph of the Pyramids of Giza, which was used on the front page of one of their editions. Out of aesthetic purposes, the two pyramids were placed closer to each other than they were on the original photograph, resulting in an image that better fitted the size of the front page. Although the alteration might not have had far-reaching complications, it still alarmed scientists. For example in 1994, Christopher Anderson wrote an article in Science in which he referred to the incident and warned for the greater implications of digitally manipulated images in the scientific field.

For my own field of interest, digital photo manipulation can be used as a tool to drastically improve the quality of historical photographs. It even makes it possible to fully colourise historical photographs of which the original version is in black-and-white. This technique has reached a level in which there are algorithms out there that can do this without any human interference. Websites like Algorithmia or ColouriseSG offer the opportunity to upload a grey scaled photograph and turn it into a vivid colourised image. Although these services are not perfect, it can still be a fun tool to make your old photographs feel more alive. It is important to stress that the goal of these services is to create plausible colours, it is possible that these do not always match the actual colours in real life.

A session of the senate of the University of Leiden in 1949. The image on the right has been generated by the website ColouriseSG.

Instead of this only being a fun thing to do, colorizing photographs can also improve our understanding of and our relationship to history. An example of this is the project Faces of Auschwitz, where the black-and-white photographs of prisoners in the concentration camp are being colorized. As dr. Waitman Wade Beorn explains in the video below, this can improve our relationship to history.

As photo alteration can enhance our experience of history, it can also distort our understanding of history, as it opens the door for other kinds of alterations. To catch a glimpse of the possibilities, just take a look at the work of Jane Long, an artist who not only colorized historical photographs and improved their quality, but also transformed the photographs into surreal images where many new elements are added. Because of the surreal context, and also because the artist showcases the original images, it is not hard to spot that alterations have been made. However, it indicates how photographs can be enhanced in a way that they are taken out of context. The work of Jane Long is an innocent playing around with this, but you can imagine there are instances where alteration of historical photographs can really become a problem.

It is then important that with every manipulation, we are aware that an alteration has been made and we also know the content of the alteration. But how do we do this? As Anderson already argued in 1994, it is important that we safeguard the original. In this way, we can compare the image with the original historical photograph and thereby conclude which alterations have been made. The above mentioned projects are great examples of this, as they show both versions of the images.

Of course, this only works when we know that an image has been digitally altered. Otherwise, trying to gather information about the origin of the picture might still be an option, for example doing a Google reverse image search, but this will not always suffice. Fortunately, some research has been done into techniques that are able to spot alterations to an image without the need for the original image. A research paper from scientists of the Tokyo Denki University highlights the use of a technique based on ‘Reversible Histogram Shift’, that as the paper shows leads to interesting results. And just this year, an article was published that proposed a technique to detect digitally colorized images based on ‘Convolutional Neural Networks’ (CNN).

It is easy to blame the techniques of digital image manipulation for possible complications, but in the end (like with all technologies) it are humans who decide how the techniques are being used. As I have tried to show in this piece, digital photo manipulation is not necessarily a bad thing. However, in times of fake news, deep fakes and whatnot, we have to be constantly aware that the images we see online might be tempered with and we should know how to adress this.