A semiconductor die is provided on a spacer, the die having first and second opposite edges which extend beyond respective first and second opposite edges of the spacer, the first edge of the die extending beyond the first edge of the spacer to a lesser extent than the second edge of the die extends beyond the second edge of the spacer. The method involves producing a contrast value for each pixel in the input image, the contrast value being proportional to an intensity gradient between each respective pixel and at least one pixel adjacent the respective pixel. In addition, the parallax between the first detected area and the searched area having a change in brightness is compared, a search area having a parallax that differs from that of the first searched area is eliminated, and a search area having a parallax identical to that of the first searched area is provided a highlighted display as an object identical to that of the first detected area. The lamp body includes a handheld part and a lamp holder. This finds use in maintenance of sperm viability to increase the success rate of artificial insemination.