[iframe]http://www.yorku.ca/eye/afterima.htm[/iframe]

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[这个贴子最后由netecflash在 2001/12/30 06:28am 编辑]

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[iframe]http://www.yorku.ca/eye/illusion.htm[/iframe]

[iframe]http://www.illusionworks.com/[/iframe]

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[这个贴子最后由netecflash在 2001/12/29 02:27am 编辑]

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[这个贴子最后由netecflash在 2001/12/29 02:28am 编辑]

[iframe]http://www.yorku.ca/eye/popepix2.htm[/iframe]
[color=red]Pixelized Photograph Explained[/color]
A normal color photograph has a continuous gradation of colors. What has been done in this photograph is to divide the photograph up into little boxes and place in each box the average color and intensity of the area that it covers.
In point of fact this is true of the original photograph. But there the boxes are so small you can't see them. If you have a magnifying lens, try looking at a photograph printed in a newspaper. There you can easily see the array of dots (they use dots not squares) that make up the picture.
When you squint or use some trick to blur the image on the computer screen the picture looks more normal. And if you did not recognize the display as being a picture of Pope John Paul II, you probably will once you blur the image.
In the jargon of imaging science the Pixelized version of the photo removes a lot of the high spatial frequencies in the original photograph and replaces them with high spatial frequency noise. This high spatial frequency noise is removed by when you blur the Pixelized picture and the photo of the Pope looks a little more normal.

[iframe]http://www.yorku.ca/eye/ponzo%20illusion.htm[/iframe]

[这个贴子最后由netecflash在 2001/12/29 02:34am 编辑]

[iframe]http://www.yorku.ca/eye/radialns.htm[/iframe]
[color=red]Radiating Lines[/color]
You undoubtedly saw a square figure which had a small rather light square area in the center and increasingly darker perimetric strips extending to the edge. You probably also saw bright arms radiating diagonally out from the center.  This figure was adapted from a chromatic version designed by V. Vasarely (Arcturus (1970) as reported in Hurvich, 1981.
These brighter diagonal areas are physically not in the figure. That is to say, if you were to use a light measuring instrument (a photometer) and measure the amount of light coming from any of the concentric perimetric strips you would find that the same amount of light is reflected from all points along any one strip. Yes, that includes that part of the strip along the diagonal where it appears brighter. Consequently, that must mean that this brightness illusion is generated in the visual system. Just incase I have confused you, perhaps looking at a photometric plot of the illusion will help.
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[这个贴子最后由netecflash在 2001/12/29 02:36am 编辑]

[iframe]http://www.yorku.ca/eye/vase.htm[/iframe]
[color=red]Reversible Imagep[/color]
Some people see the outline of two black faces opposite each other. Other people see a white vase. Sometimes people see the faces and vase alternating and yet other people can see both the faces and the vase simultaneously.
Select reversible diagram to see the illusion again.

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