Why MSER objects shows different color?

I am trying to understand the feature named MSER (Maximally Stable Extremal Region).

Can someone tell me why MSER objects shows different color. I have applied MSER features on a normalized gray scale image. The image normalized mainly in red and blue channel. To detect road sign. It detects perfectly. But i need to know why it shows different color.

In the image first one is input image, than gray image, last one is MSER region objects.

Can someone please explain or share me some effective reference. I have searched all the matlab documentation but didn't find why it shows different colors.

[shabnam sh]

your code is working perfectly ? only to find red and blue signs or you have added other colors as well ?