Remove brighter regions in an image on frequency domain
It is important to understand what the frequency domain means. The bright regions in an image correspond to pixels with a certain value, whether it be color or gray scale. Frequency domain has the interpretation of looking at how fast the values change, not their values. For example, think about an image of a dark blue car against a white background. The pixels along the edge may change from dark blue to white just by moving a few pixels, this is high frequency because the change in pixel value is high over a just a few pixels. This is different from a picture where you have dark blue which slowly fades to white over many pixels. Filtering in the frequency domain on an image would be affecting how the pixels change in value. For example, using a low pass filter on the dark blue car picture I mentioned, would block the high frequency components. This means the sharp changes in pixel value, like on the edge between the dark blue car and white background, would be smoothed (blurred) out.

Is it possible to remove white pixels from an image with frequency domain filter? No, and if you need to do that it would be better to just scan the image for pixels with a white value or value above some threshold and remove those pixels.