Patent ID: 8091493

Claim:
A sewing machine comprising: an image pickup device that is disposed at a position where an image can be picked up over a sewing machine bed; a feature point coordinates calculation device that extracts a plurality of feature points arranged over a range such that the image pickup device can pick up images therein from the image picked up by the image pickup device and that calculates two-dimensional coordinates of the extracted feature points as feature point coordinates; a reference coordinates storage device that stores reference coordinates, which are previously measured three-dimensional coordinates of the feature points; a correlation device that correlates the reference coordinates stored in the reference coordinates storage device with the feature point coordinates calculated by the feature point coordinates calculation device; a parameter calculation device that calculates a parameter about the image pickup device based on a result of correlation by the correlation device; a parameter storage device that stores the parameter calculated by the parameter calculation device; a comparison image acquisition device that acquires the image picked up by the image pickup device as a comparison image; a first determination device that determines whether comparison information that is based on the comparison image acquired by the comparison image acquisition device matches with parameter information that is based on a basic image that was used to calculate the parameter stored in the parameter storage device; and a first notification device that notifies that it is necessary to re-calculate the parameter if the first determination device has determined that the comparison information and the parameter information do not match with each other, wherein the comparison information and the parameter information which are determined by the first determination device as to whether they match with each other are respectively at least one of: the comparison image and the basic image; the feature point coordinates calculated based on the comparison image and the feature point coordinates calculated based on the basic image; and the parameter calculated based on the comparison image and the parameter stored in the parameter storage device.