"A Javascript program to create images of color illusion by histogram compression in RGB"
made by Akiyoshi Kitaoka for ECVP2021 Showtime!

(2) Set the following values (parameters) and press the button below.
  R min - max    G min - max    B min - max

(This transformed image can be downloaded by right-clicking on it.)

(original image)

For those who are still getting used to it:
  This program can automatically determine the best parameter for you! (though not perfect:D)
  Select the target color by clicking on the image above, and press the button below.

target color:    R   G   B
the color after change: R   G   B

Press the left button if all the histograms are not drawn.   magnification: x


This color illusion production program takes advantage of the fact that the human visual system behaves as if it is perceiving a distribution of RGB values that is corrected to be in the range of 0 to 255.


Kitaoka, A. (2019). Two types of spatial color mixtures and color illusions. EIP19 (Empirical Research in Psychology), Belgrade, Serbia, March 30, 2019. Presentation (html)

Shapiro, A., Hedjar, L., Dixon, E., & Kitaoka, A. (2018). Kitaoka's tomato: Two simple explanations based on information in the stimulus. i-Perception, 9(1), January-February, 1-9. PDF (open access)

other pre-prepared images

The address of this webpage is available from:



An electronic image is made up of pixels whose sub-pixels are RGB. Each of RGB has a value of 256 gradations, where '0' means the darkest and '255' means the brightest. In most cases, an image of an object or landscape contains all gradations from 0 to 255 for each of RGB. When the range of those gradations is narrowed, color illusion is likely to occur. My demo is a Javascript program that creates color illusion by manipulating the range of gradations of each of RGB. Here I name this manipulation 'histogram compression.' Suppose you have an image of red strawberries. The R gradations of the image are compressed downward, say from 0 to 128, and the G and B gradations are compressed upward, say from 128 to 255. Then, pixels of red hue disappear, but the strawberries will continue to look red. This is a kind of color constancy phenomenon, but it is also a color illusion in the sense that objects appear to be reddish even though there are no red hue pixels. In my demo, I designed it so that you can try images of various colors. The demo (shown below) is available to anyone who has access to the web. Enjoy!


(Staff only)