Image processing method and image processing device for generating rectangular mask in image according to different field of views

An image processing device comprising:

• an image obtaining unit obtaining a first image captured by a camera unit under a first field of view;
• a mask generating unit generating a first rectangular mask in the first image, the first rectangular mask having four end points and four boundaries connecting the four end points;
• an image processing unit electrically connected to the image obtaining unit and the mask generating unit, the image processing unit converting first X-Y plane coordinates of the four end points in the first image into spherical coordinates;
• wherein the image obtaining unit obtains a second image captured by the camera unit under a second field of view;
• the image processing unit converts the spherical coordinates into second X-Y plane coordinates corresponding to the second image and determines whether the second X-Y plane coordinates of the four end points all are located in the second image;
• if the second X-Y plane coordinates of the four end points all are located in the second image, the image processing unit generates a second rectangular mask in the second image by a maximum X coordinate value, a maximum Y coordinate value, a minimum X coordinate value and a minimum Y coordinate value of the second X-Y plane coordinates of the four end points;
• wherein the image processing unit converts the first X-Y plane coordinates of a plurality of boundary points of the four boundaries in the first image into the spherical coordinates;
• if the second X-Y plane coordinate of at least one end point is not located in the second image, the at least one end point is assumed to be an out-of-bounds point and the other end points are assumed to be in-bounds point if at least one out-of-bounds point exists, the image processing unit finds out at least one boundary point located in the second image and close to the at least one out-of-bounds point from the plurality of boundary points;
• the image processing unit generates a third rectangular mask in the second image by a maximum X coordinate value, a maximum Y coordinate value, a minimum X coordinate value and a minimum Y coordinate value of the second X-Y plane coordinates of the at least one boundary point and at least one in-bounds point.