Off-subtracted surface brightness images at 3.6 μm for the sources of the sample. The image sizes have been adjusted to show the sources at the same distance in order to visualize the source sizes. Most cores have a complex shape, and the diffuse signals differ with respect to the peak brightness and point source contamination. In the case of Rho Oph 9, the image has not been off-subtracted and the bright emission in the upper left corner is caused by transiently-heated particles and not by coreshine. The crosses indicate the approximate location of the core center based on the corresponding 8 μm extinction maps or thermal emission maps in the FIR/mm.