View Full Version : Great optical illusions with color contrast

08-14-2002, 07:20 AM
Anyone interested in how color and value contrasts work in an image has got to check out the cover story of the MAY-JUNE 2002 issue of American Scientist. The pictures are amazing, starting with the cover which shows a cube covered with colored dots. The light is from the upper left. The brightly lit top of the cube is covered with yellow dots with a dark (almosy black) blue dot in the center. The side of the cube in shadow is covered with dark gray/black dots with a glowing, almost electric blue dot in the center. The amazing thing is that both blue dots are acually the same color! I had to use two cards with punched holes in them to block out everything but the blue dots before I could admit that this was true. Inside there are more images showing that the exact same shade of gray can be used to represent a white object in shadow or a dark (even black) object in bright light.
Oh, why don't I just show you the cover:


08-14-2002, 02:38 PM
This is cool. I didn't believe that those two blue dots were the same, so using a painting program, I cut them out and placed them side by side. Yup, they're the same...couldn't believe it. This is the most convincing example of this illusion I've seen.

08-15-2002, 08:33 AM
Domer, How did you cut that shape out? Which program are you using?

Is there a way to cut a person out of one photograph and superimpose that person on top of another photo using either photoshop 5.o or in MGI photosuite? Those are my programs.

Great article, DuhVinci,( great name) hope the library has it.


Drew Davis
08-15-2002, 01:33 PM
Photoshop lets you cut arbitrary shapes out of an image and paste it into another. It can be a little tedious getting all the edges just right (unless the colors are so different the "magic wand" select tool can do all the work), and then of course you have to blend it into the destination image.

08-15-2002, 10:32 PM
I used Fractal Design Painter, but other programs allow you to do the same thing. Yes...it usually takes a lot of work to get it to look 'right' though it can be done. Just make sure the lighting/light source is the same in both pictures (it would be odd if you have shadows on opposite sides :confused: )

08-22-2002, 06:03 PM
I discovered the same optical illusion in a layout I did for an animation project. The bricks in these two buildings are exactly the same color.

08-24-2002, 12:26 PM
So glad I decided to look in here today! This is something which I have seen demonstrated on a TV programme here by Jenny Wheatley, a very exciting artist. She painted quite strong colours onto a sheet of paper, then took another sheet of very dark painted paper with a hole cut into it and held it over the first colour. The originally strong colour looked almost anaemic!