Quote:
Originally Posted by CraigD
As hard to believe from the evidence of our eyes, what the picture’s author (Adelson) and Popular claim is true – the actual color value being sent to your screen is the same for pixels in square A and B is the same.
An easy way to verify this (I just did, since I too couldn’t believe the claim over what my own eyes were telling me) on a Windows machine is: - View the picture in you browser (upper left hand corner of you screen will save hassle in later steps)
- Hold down the Ctrl key and press the PrtSc key to copy the current screen bitmap to the clipboard
- Run mspaint.exe (or select “Paint” in the start menus).
- Hold down Shift and press Ins (or click Edit, Paste) to copy the clipboard to the new drawing.
- Click to select the “Select” tool (looks like a dotted-line box)
- Click and drag over a portion of the A square in the picture
- Hold down Ctrl and press Ins (or click Edit, Copy) to copy the selected region to the clipboard
- Hold down Shift and press Ins (or click Edit, Paste) to copy the clipboard to the new drawing.
- Drag the pasted region to an unused part of the drawing
- Repeat steps 6-9 for a portion of the B square, placing the 2 copied regions close together.
You’ll be able to clearly see that A and B are the same color.
Unless you believe that mspaint.exe has hidden software to transform the colors copied via the select tool, this exercise is compelling proof of Popular and Adelson’s claim. |
First, I did not say that the picture of the checkerboard with an A and a B are not the same. I said that you cannot prove it without using a method that actually selects the sample and gives you a numerical reading of the picture.
The method you have prescribed here still only leaves you a perception of the two colors and not an accurate numerical analysis of them. For this you need a program better than paint. A program that can give you a precise measurement of the two samples and tell you with certainty what the color of the two images are.
The original post of this thread shows an illusion of two objects each with a yellow (or was it grey) center piece. However, each object has been screened by a film of colored material (one yellow, one blue). If the author understood optics, this is not an illusion. The actual wavelengths of light filtered out by each color filter mean that what reaches the eye from each side is fundamentally different. Thus when one views the picture with the filters in place, one is seeing two different colors (not their mind makes them think there are two different colors.) This can be verified with a program like cs2 which allows you to create custom color palletes by selecting a portion of an existing picture to give you an exact match to that color. This custom pallete then gives you a precise readout of the different color levels (RBG or CMYK) as well as saturation and hue and other things.
Do not leave it up to the eyes.
