Embodiments of shielding apparatuses are disclosed herein. A first silicon oxide layer is formed on the front surface of the semiconductor substrate and, simultaneously, forming a second silicon oxide layer on the backside of the semiconductor substrate. Each of the first plurality of Gilbert cells and the second plurality of Gilbert cells includes n m-input Gilbert multipliers, in which n is an integer greater than and m=. Each image is divided into dots, luminance data of the dots of each image is converted into binary data items of white areas and black areas with reference to a threshold value, and the number of black areas is counted.