Impenetrability doesn't argue against image theory
The cognitive impenetrability condition doesn't refute image theory because the image theory doesn't assume that all image processes are cognitively impenetrable.
The image theory acknowledges that some image processes are cognitively penetrable, whereas others are not.
The theory also recognises that determining which are which is an important research issue.
Stephen Kosslyn, Stephen Pinker, George E. Smith, and Steven P. Schwartz (1979).