Contrary to what you may think first, the blue and the green are not two different colors. Use Photoshop or any other tool to zoom in and check the exact color values. They’re the same.
The choice of colors is making this field of dots totally warped. But it’s not. Some other colors may not work as well, but it’s still operating quite well in black and white.
It is quite impressive to see how the eye can be tricked when hiding the shades transitions. so simple an optical illusion. YouTube link
Light green and light blue spirals seem to have different colors. But don’t believe your eyes. They really have exactly the same color (described in HTML with the following fundamentals: R=0, G=255, B=150).