The closest match from life I've been able to find is two images at: https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:00f5fe30-6003-4720-914b-ea3e81663714#gallery These images suggest the moth in life is black and grey rather than brown , see the LBH link: http://lepidoptera.butterflyhouse.com.au/pyra/fuliginosa.html Bold Systems 4 shows blacker set specimens.
The exact shade of grey or brown reproduced in a photo is very dependent on the spectral composition of the illumination, so I do not think it should be used diagnostically.