Discover an image from under bright color bars

Background

Given a black & white image covered with bright color bars, the goal is to identify it. The original image is still visible, though it isn't sharp enough to identify.

Question

Given a pixel as RGB format, I need to identify if it's colored or black & white. Should I compare it to a range of values?

After identifying I would like to reverse the pixel to the original one black & white. What calculations should I do without overwriting the original pixel?

I've tried to zero values that might indicate colored pixels, but this technique overwrote the original image behind the color bars.

Final Result

After reversing the original image should be visible enough.
Thanks in advance.

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