Abstract: An image processing circuit captures an image of an capturing object and obtain an image of the capturing object, detects brightness in each criteria region in the image, computes a difference in the brightness of two adjacent criteria regions, determines a position of the capturing object in the image corresponding to a pixel having a brightness greater than a predetermined value on a basis of the difference in the brightness.

Abstract: A star tracker captures an image of a star and output the image, searches out, from a plurality of pixels constituting the image, a peak pixel having a luminance value higher than luminance values of neighboring pixels neighboring the peak pixel, determines an extraction range from which to extract, from the image, a partial image containing the peak pixel, and computes a star position based on luminance values of a plurality of pixels constituting the partial image. The apparatus determines the extraction range based on at least one of the luminance value of the peak pixel, a position of the peak pixel within the image, and a parameter correlated with a temperature of the image sensor, such that noise in the partial image is reduced.