Illusive Color Mixing

When your brain lies… There is NO yellow, nor red, nor green in the picture below! The only real colors are blue, cyan and magenta. Scientists and artists call these color induction effects “simultaneous color contrast” and “color assimilation”.

Concept taken from my book “Drawing Optical Illusions” (2010).
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Math-Magic Vanishing Space

Qaudrix puzzle 1

Inspired from the astrological tables, here is a new puzzle of my creation designed according to the ‘Golden Number Rules’, which is reflected in the proportion of each single piece of the game. Thanks to the balanced dimensions of its pieces, this puzzle acquires some intriguing magical properties!

This “math-magical” puzzle is composed of a tray in which the pieces are assembled.

Quadrix puzzle 2

Puzzle Quadrix (aka Quirinus), © 1992, G. Sarcone.

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Amazing Brightness Constancy Effect

Look carefully at the saw-tooth wave patterns on this picture. Is the background of the picture uniformly gray or are there different shades of gray?

Kolozanges (2013-2021), © Gianni A. Sarcone

Brightness constancy makes some vertical strips look darker, when in fact the gray background is all the same shade of gray.

This op art work is available as prints and canvases from my official online Gallery.

Turning Gray Shades Into Colors With A Tinted Geometric Grid


This is an old technique that uses the “color assimilation” effect to colorize pictures. This perceptual effect, also known by scientists as the Von Bezold spreading effect, occurs when our visual system transfers perceived colors to their adjacent areas.

Is the first photo of a variety of pumpkins in color?

colorized black and white pumpkins
Black and white photo overlaid with a geometrical tinted grid

Paradoxical Elastic Squares

A math-magic article I wrote for the German magazine Zeit Wissen: with the 13 triangular and square pieces (fig. 1) it is possible to form two large squares shown in fig. 2. Though the second large square has an extra piece the dimensions of the squares seem to be the same! Can you explain why this is possible?

This puzzle is available as greeting cards from my online store.

Ghost Colors

This is one of my earliest color optical illusions. There is no yellow or green in the diamond shapes, just vertical black lines! (If you don’t believe it, use a eyedropper tool to check it.) This intriguing visual effect is mainly due to “simultaneous color contrast induction“.

Illusive colors
Ghost Squares / Black Diamonds (2002 – 2007)
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Scintillating Starburst: Seeing rays that aren’t there…

This is one of my oldest illusions I created in the 90s. In the picture you may see ghostlike dark radial beams. This illusion is a variant of the Herman’s scintillating grid illusion. I designed this illusion just by turning 45 degrees the Herman grid and then by applying a polar transformation.

From my book “Eye Tricks“, 2001-2007.
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