Watercolor illusion

Figure 1. A figure similar to that of Figure 1 of Broerse, Vladusich, and O’Shea (1999),[1] demonstrating what became known as the watercolor illusion. The vertical gratings are black and white with a thin line of red along each black bar. The horizontal gratings are black and white with a thin line of green along each black bar. The illusion is that the red and green appear to spread over the black and white regions of the vertical and horizontal gratings respectively.
Figure 2. Figure 1 from Pinna (2008).[2] Purple undulated contours adjacent to orange ones are perceived as a map of the Mediterranean Sea (picture a) and the Gulf of Mexico (picture b) evenly colored by a light veil of orange tint spreading from the orange contours (coloration effect). The two shapes show a strong figure-ground segregation and a solid figural appearance comparable to a bas-relief illuminated from the top and to rounded surfaces segregated in depth and extending out from the flat surface (figural effect). On the contrary, the complementary regions appear as empty spaces with the appearance of holes.

The watercolor illusion, also referred to as the water-color effect, is an optical illusion in which a white area takes on a pale tint of a thin, bright, intensely colored polygon surrounding it if the coloured polygon is itself surrounded by a thin, darker border (Figures 1 and 2). The inner and outer borders of watercolor illusion objects often are of complementary colours (Figure 2).[3] The watercolor illusion is best when the inner and outer contours have chromaticities in opposite directions in color space. The most common complementary pair is orange and purple.[4] The watercolor illusion is dependent on the combination of luminance and color contrast of the contour lines in order to have the color spreading effect occur.

  1. ^ Broerse, J.; Vladusich, T.; O'Shea, R. P. (1999). "Colour at edges and colour spreading in McCollough effects". Vision Research. 39 (7): 1305–1320. doi:10.1016/S0042-6989(98)00231-4. PMID 10343844.
  2. ^ Pinna, B (2008). "Watercolor illusion". Scholarpedia. 3 (1): 5352. Bibcode:2008SchpJ...3.5352P. doi:10.4249/scholarpedia.5352.
  3. ^ Tanca, Maria; Grossberg, Stephen; Pinna, Baingio (2010). "Probing Perceptual Antinomies with the Watercolor Illusion and Explaining How the Brain Resolves Them". Seeing and Perceiving. 23 (4): 295–333. CiteSeerX 10.1.1.174.7709. doi:10.1163/187847510X532685. PMID 21466146.
  4. ^ Devinck, F.; Spillmann, L. (2009). "The watercolor effect: Spacing constraints". Vision Research. 49 (24): 2911–2917. doi:10.1016/j.visres.2009.09.008. PMID 19765603.