Simultaneous registration of multiple image fragments

In a digital image alignment system, a method for aligning more than two image fragments to assemble a complete image, the method comprising the steps of:

• receiving a list of overlapping image fragment pairs for the more than two image fragments, each overlapping image fragment pair having an overlap alignment and being associated with an alignment measure based on the overlap alignment, the list of overlapping image fragment pairs being associated with a total alignment measure, the total alignment measure being a sum of alignment measures for each of the overlapping image fragment pairs;
• selecting an overlapping image fragment pair from the list of overlapping image fragment pairs;
• adjusting the selected overlapping image fragment pair to arrive at an improved alignment from the overlap alignment of the selected overlapping image fragment pair;
• calculating the total alignment measure for all pairs of overlapping image fragments based on the improved alignment for the selected overlapping image fragment pair;
• determining whether the improved alignment produces an improvement in the total alignment measure;
• applying the improved alignment to the selected overlapping image fragment pair if the determination indicates that the total alignment error would improve as a result of applying the improved alignment, otherwise discarding the improved alignment to the selected overlapping image fragment pair if the determination indicates that the total alignment error would not improve as a result of applying the improved alignment;
• and
• repeatedly applying the selecting step, the adjusting step, the calculating step, the determining step, and the applying step to successive overlapping image fragment pairs to improve the total alignment measure.