Haloing is a photographic term that refers to the creation of a halo or a bright outline around a subject due to overexposure. The antonyms for haloing could be 'underexposure,' which means a lack of light or brightness, resulting in a dark and shadowy image. Another antonym of haloing could be 'clarity,' which refers to the sharpness and definition of a subject, rather than a hazy and indistinct outline around it. Additionally, antonyms could be 'subdued' or 'dull,' which means a lack of brightness or vibrancy in the image, as opposed to the bright and glowing effect of haloing.