The "Face on Mars" photograph taken by Viking 1 in 1976 of the Cydonia region on Mars has multitudinal similar sized small dots in a seemingly random pattern all over it. Are all those dots impact craters and if not what are they?
Are all those dots impact craters and if not what are they?
They are artifacts of some sort.
They could be salt and pepper noise, but I suspect not. If it was salt and pepper noise the image would also have lots of white dots, which it does not. These artifacts are instead missing data. The standard standard approach with regard to imagery errors traceable to the pixel level is to give the suspect pixels an off-scale low or off-scale high numerical value (which appear as black or white) and mark them as suspect or missing in the metadata. Quoting from photojournal.jpl.nasa.gov,
The speckled appearance of the image is due to missing data, called bit errors, caused by problems in transmission of the photographic data from Mars to Earth. Bit errors comprise part of one of the 'eyes' and 'nostrils' on the eroded rock that resembles a human face near the center of the image.