A chart generation unit generates an adjustment chart, and a projection unit projects the adjustment chart onto a circular cylinder. A parameter acquiring unit acquires 12 parameters in total, relating to the positions of four corners and middle points of a top side and a bottom side of a chart and lateral expansion of the chart, the chart being input by a user through manipulations of an operation unit. A transform function determination unit calculates, from the total of 12 parameters, an accurate transform function for projecting an image onto the circular cylinder. An image conversion unit applies geometric transformation to the image based on the calculated transform function.