An image processor with a self-focus scheme to estimate the center of the solar disc is presented in this chapter. It can be utilized in the automatic tracking module on a HCPV power generation unit to closely follow the solar center with high precision under various weather conditions. To start the proposed procedures, a photo containing the solar image is taken first by a digital sensing device. Then, it is sent to the algorithm and goes through a series of steps to identify and to isolate the solar image. Finally, the solar center is located by the three-point center method. The proposed scheme, based on a weighted brightness factor of the image, evaluates the image center by comparing the estimated solar diameter to the reference one and iteratively modifies the thresholds in the image isolation step. The results show total processing time can be a fraction of a second and the estimation accuracy reaches to less than an arc second, depending on the pixels in the taken photo.