1. An image processing method of a robot system, the method comprising: acquiring an original image by a robot; generating, by a processor, object password information based on an object image of the original image, the object password information being used to restore the object image of the original image; and generating, by the processor, a low-resolution image of the original image by converting a resolution of the original image into a low resolution, wherein the generating of the object password information includes detecting an object region corresponding to the object image of the original image, clustering the detected object region based on a similar feature, generating cluster information indicating which cluster the object region belongs to, and generating a high-resolution basis vector used to restore the object image.