Nonrigid Image Registration in Digital Subtraction Angiography Using Multilevel B-Spline

Table 2

Comparison of registration results for three different control point selection approaches for ten simulated image pairs.

Image pairs	Initial error before registration	Error of the control point pairs after registration
		Edge-based approach				Exclusion technique				Proposed hybrid approach
	RMS (𝛿0)	Max	Min	RMS	(𝛿0−𝛿)/𝛿0%	Max	Min	RMS	(𝛿0−𝛿)/𝛿0%	Max	Min	RMS	(𝛿0−𝛿)/𝛿0%
No. 1	6.098	13.115	0.103	2.861	53.1%	12.741	0.144	3.437	43.6%	7.591	0.048	1.486	75.6%
No. 2	6.892	10.090	0.030	3.192	53.7%	12.556	0.109	3.925	43.0%	3.097	0.045	0.881	87.2%
No. 3	6.442	12.071	0.042	2.642	59.0%	10.972	0.047	3.419	46.9%	7.378	0.109	1.302	79.8%
No. 4	6.201	10.548	0.102	2.711	56.3%	11.827	0.064	2.769	55.3%	3.818	0.008	1.061	82.9%
No. 5	6.363	9.792	0.164	2.781	56.3%	9.461	0.057	3.005	52.8%	5.673	0.058	1.289	79.8%
No. 6	6.270	7.903	0.162	2.242	64.2%	9.798	0.075	2.336	62.7%	2.934	0.035	0.960	84.7%
No. 7	6.813	9.606	0.066	3.312	51.4%	10.540	0.107	3.456	49.3%	5.497	0.037	1.614	76.3%
No. 8	6.920	12.286	0.079	3.389	51.0%	14.201	0.061	4.359	37.0%	3.666	0.064	1.229	82.2%
No. 9	7.399	11.843	0.013	4.152	43.9%	13.573	0.052	3.932	46.9%	5.925	0.085	1.490	79.9%
No. 10	7.494	15.460	0.051	5.423	27.6%	11.019	0.051	3.645	51.3%	7.293	0.011	1.643	78.1%
Average	—	—	—	—	51.6%	—	—	—	48.9%	—	—	—	80.6%