Presently Adobe Target does not allow for an easy way to adjust or provide images for mobile browsing. The asset manager does not create mobile renditions as Adobe's DAM product. One of the advantages (and reasons we adopted Target) was it's integration and ease of use with AEM however the lack of mobile optimization outside of arduous hand coding when working with AEM/DAM renditions is disappointing. Please look into having mobile renditions created in the Target asset manager as is a feature of the DAM.
