Hello,<br>I know what you are thinking...why are you up-sampling an image? Here is the situation and problem and I hope that you can help.<br><br>I have an image of vectors (3D image, 3D vectors) that is of a course resolution (35,20,20). These vectors represent the displacement of a grouping of pixels in a fixed image. Each voxel in the vector image represents the average displacement of 21x21x21 voxels in the fixed image. What I want to do is linearly interpolate the data from the course vector image into the grid (they occupy the same space) of the fixed image. The new vector image will then be used to morph the fixed image into the moving image space, giving a deformable-like transform, and then the fixed and moving image can be operated on in the same space.<br>
<br>The problem is that when interpolating the values at the edge of the vector image the interpolator uses a single value for the out-of-bounds pixels. This means that the vectors at the edge of my new vector image converge to the displacement represented by the out-of-bounds value (a constant). What I would like, is to have the edge given a zero derivative (Neumann) condition (or even better, be able to try a few different boundary conditions). I have looked through the interpolate and resample filters and can't seem to find this already implemented. Has this been done, or should I just get on writing it myself?<br>
<br>Thanks for your time and help.<br><br>Regards,<br>Seth<br>