The mechanism of image contrast formation in aberration-corrected scanning confocal electron microscopy (SCEM) is studied. Studies of image formation mechanism in high-resolution SCEM have been based on the application of a linear imaging theory from confocal optical microscopy, the wave function formulation used for STEM, and imaging within a Bloch wave framework. Mitsuishi and co-researchers approached SCEM imaging within the framework of Bloch wave theory. The SCEM images were shown to be coherent in nature and displayed complicated contrast variations and reversals. The study starts by considering the image contrast for a single isolated atom and making the weak phase object approximation for the transmission function. If the aberrations in both lenses are equal and opposite, as they would be for the confocal condition then the first term is completely real. The contrast is observed only when the double integral is close to being perfectly imaginary, to create a real second term.