Use the mouse to drag and explore the moiré interference
Initially there are two
images overlaid, a circular and a square one. All the images are
moveable, simply click and drag using the mouse. Try all the
combinations you can, including on this text. For best effects,
move the images very slowly when they are superimposed. For a
closer look, enlarge the images using the button below.
What is going on here? The illusion is based on moiré fringing.
The backgrounds are regularly spaced square dot patterns. When
the patterns are superimposed the dots interact and new patterns
are formed. The images are simple GIF files with white background
set to transparent to allow the interaction to take place. The
images were set using a screen display setting of 600x800. There
is also another effect intruding - the screen display adds lines
into the image display. If you are unlucky, then your monitor will exhibit
Moiré effects without prompting!