Replacing the "cover images" after 3D model has been constructed?

Hi all,

Is there a way to replace the cover images after 3D model has been generated? The reason I ask this question is I would like to replace the cover image with masking image. For example, I would like to highlight the crack in this model

by replacing the images with masking images (black and white) and and finally update and attaching new images on the following model. 

Thank you for the help.