In a previous post, I went over the three types of image duplications that can be found in biomedical papers. Those types of duplications, however, might be hard to understand for people who are not familiar with scientific photos of western blots or biological tissues.
In this post, I want to give some simple, non-scientific examples, to better explain which types of duplications I am looking for in published papers.
In the examples below, I have used six copyright-free images taken from Unsplash.com. These images were uploaded by users Michaela (@m_hampi), Jasper Boer (@jasperboer), Mikk Tõnissoo (@themikk), Mike Baker (@bike_maker), Chloe Leis (@tsunamiholmes), and Ethan Robertson (@ethanrobertson). I thank them for making these images available for reuse.
All six images are from palm trees in the setting sun. Although they are all similar (dark palm trees, sea, and a sunset sky with hints of blue and orange), it is clear that all photos are different.
Now let’s take a look at some different rearrangements of these photos and try to spot the duplications. I distinguish three different types of duplications, as I explained in the older post “Scanning for Duplications“:
- Category I duplications: simple, identical duplications.
- Category II duplications: in which two photos are shifted or rotated.
- Category III duplications: in which parts within the same photo are duplicated.
In several examples below, I hope to explain these three types of duplications using the photos of the palm trees in the sunset shown above.
Two figures without duplications
In this first example below, the 6 photos are arranged in 2 figures. The 2 figures are different from each other, and each figure contains three different photos. There is no overlap between the photos (panels) shown in Figure 1 or 2. These are therefore two good figures without any duplication. If these were two figures in a science paper, and each of the 6 photos would represent a different experiment, this would be two good figures, without any problems.
Type 1 duplication: a simple duplication
In the example below, Figure 1 contains a duplicated panel. This is what I call a “simple” duplication (category I). The same panel/photo is visible twice within the same figure. Can you spot which figure has a duplication?
This duplication should not be too hard to find. Here is the duplication, marked by me with red rectangles around the panels that are duplicated. So, in this case, Figure 1 contains a duplicated panel, while Figure 2 is fine.
In the example below, a panel in Figure 1 also is visible in Figure 2. Can you spot which one? This is another example of a “simple” duplication (category I).
The middle photo of Figure 1 was inserted again at the top of Figure 2. To draw attention to the panels that appear to be duplicated, I have drawn green boxes around the duplicated photos. It is now easy to see which two photos appear to be the same.
Can you spot the Type I category duplication in the example below? It is easy to find.
Type II duplication: duplication with a shift
Now let’s take a look at type II duplications. In this type, two images will be partially the same, but with a shift, a rotation, or a flip (mirror image). In the example below, a panel in Figure 1 partially overlaps with a panel in Figure 2. Can you spot the overlap? This is a “shifted” duplication. The middle photo of Figure 1 partially overlaps with the photo at the top of Figure 2.
Here is how I would mark the duplication: I draw rectangles of the same color around the area that the middle panel in Figure 1 appears to have in common with the top panel in Figure 2. Now it becomes very easy to see that the two photos show an overlap.
Here is another example, in which two images are identical, but one of them is in mirror image. Can you find it?
This is how I might mark this type II duplication. I draw colored rectangles on the panels that are identical, and I add arrows to show the orientation of the two panels. In this case, it is a horizontal mirror copy.
Can you spot a Type II duplication in the figures below?
Type III duplication: Duplication within a photo
In the example below, both figures appear to contain no duplicated panels – but there is a duplication within one of the photos. Can you spot it? I am a really bad photo-manipulator, so it should be pretty obvious.
In the middle panel of Figure 2, two palm trees are duplicated. Below is how I might mark them to draw attention to the duplication.
Can you spot a duplication in one of the photos below? One of the panels has 5 copies of the same palm tree.
Duplications in scientific images
In this post, I used simple examples of photos to show three types of duplications. You can see examples of biomedical figures with these duplications in my older blog post called “Scanning for duplications“.