A comprehensive demonstration of similar illusions can be found in Nicolas Wade’s excellent book “Art and Illusionists” 11.ĭespite the fact that the panda in the panda illusion becomes visible by the same mechanisms as those in hybrid images or in Dalí’s painting, i.e. In this case, low-pass filtering of the image possibly increases the signal-to-noise ratio 9, 10. However, in contrast to the former illusions, in this painting the second image is conveyed by the high spatial frequencies introduced by the edges of the blocks making up the image. Again, increasing the distance to the painting or blurring vision will reveal an image of Abraham Lincoln, hidden within the scene 8, 9. A closely related illusion is used by Salvador Dalí in his painting “Gala Contemplating the Mediterranean Sea” (Fig. By determining the distance at which the images are perceived, hybrid images can be used to assess the visual acuity of the observer 7. one image is filtered using a low-pass filter, the other with a high-pass filter 3, 4, 5, 6 (Fig.

This idea was seized again recently for the creation of so-called “hybrid images”, where an image is created by merging two different images, each one spatially filtered with distinct band-pass filters, i.e. In this painting, two figures with different spatial frequencies are overlaid and a spatial low-pass filter removes the finer details of the one figure (woman), which reveals the other figure (skull) 2.

2, left), where the figure is perceived either as a skull or as a woman looking at a mirror. The basic working principle of the panda illusion, increasing the distance to the image or introducing blur by taking off the glasses or squinting the eyes, is similar to other artwork, like “All is Vanity Ambiguous Figure” by Charles Allan Gilbert (Fig. Because the spatial frequency is related to visual acuity, we asked whether the panda illusion can be used as a test for visual acuity 1. Increasing the distance to the artwork leads to an increase in the spatial frequency of the zigzag pattern.

The spatial frequency of the zigzag pattern is uniform, however, in areas where the original image is black, the stripes are slightly thickened, allowing the panda to be perceived at a certain distance. Finally, we explain why the illusion indeed can be used to predict visual acuity and discuss the neural causes of its perception with best-corrected visual acuity. Furthermore, we demonstrate that the panda illusion is based on a 2D pulse-width modulation, explain its technical history, and provide the equations required to create the illusion. Here we present the results of the comparison between visual acuity determined using the Landolt C and that predicted from the panda illusion in 23 healthy volunteers with artificially reduced visual acuity. This led us to ask if the ability to see the panda is related to the visual acuity of the observer and if therefore, the panda illusion can be used to assess the spatial resolution of the eye. If one is too close to the artwork, it is difficult to spot the bear, however, if one steps back or takes off one’s glasses the panda suddenly appears. The illustration is composed of black-and-white zigzagged lines, which form the famous panda logo of the World Wild Fund For Nature (WWF) when seen from a distance.

To call attention to the danger of extinction of the panda bear, the Lithuanian artist Ilja Klemencov created the artwork “They can disappear”.

Art of illusion band