Improving The Oriented Image Class For Use In The Registration Framework

The original design of the ITK registration framework was based around the itk::Image class, which assumed that the pixel axes were aligned with the coordinate system axes. The itk::OrientedImage was added later as a subclass, but problems remain with its gradient calculations. Furthermore, general code that uses the itk::OrientedImage will suffer an unnecessary penalty when the image is oriented parallel to the image axes. We propose a new itk::FastOrientedImage class that alleviates these performance problems, and a change to the design of itk::ImageToImageMetric that resolves the gradient issue, and adds a number of additional capacities to the image metrics