1. An image signal processing apparatus comprising: a resolution conversion section configured to decrease a resolution of a first resolution image, and generate a lower resolution image with a resolution lower than the resolution of the first resolution image, a positional-information generation section configured to detect a moving object from the lower resolution image and generate first positional information of the detected moving object, and an information output section configured to output second positional information with an output image, the output image being the first resolution image or generated based on the first resolution image, wherein the resolution of the output image is different from the resolution of the low resolution image, and the second positional information indicates positions on the output image corresponding to the position of the detected moving object in the low resolution image, and the second positional information is generated by converting the first positional information on the basis of the resolution of the output image.