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Does anyone know what an inverse mapping function is in image processing? The paper I am reading describes image processing functions that "take input coordinates as arguments instead of pixel coordinates, allowing the result to be distorted by an arbitrary inverse mapping function."
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Forward mapping stresses compliance, uniformity, standardization, and control from the top level. Backward mapping stresses discretion, variability, and judgment at the ground level. Conventional regulation is grounded in the forward mapping approach to implementation, as have been most attempts to reform it.
11.2. Forward-mapping (or object-order) algorithms iterate over the volume data and determine the contribution of each reconstruction kernel to the screen pixels. The traditional forward-mapping algorithm is splatting, introduced by Westover [124].
A forward type mapping is a mapping from a remote data type to a comparable local data type. Forward type mappings are used when you a create a nickname for a data source object. The comparable local type for each column in the data source object is stored in the global catalog.
warp can be thought of as a mapping that sends each coordinate pair (u, v) into a corresponding pair (x, y). Any such map can be expressed as two. functions, X that determines the transformed x coordinate from (u, v), and. Y that determines the transformed y coordinate from (u, v).
There are two ways to warp an image [15]. The first, called forward mapping, scans through the source image pixel by pixel, and copies them to the appropriate place in the destination image. The second, reverse mapping, goes through the destination image pixel by pixel, and samples the correct pixel from the source image. The most important feature of inverse mapping is that every pixel in the destination image gets set to something appropriate. In the forward mapping case, some pixels in the destination might not get painted, and would have to be interpolated. We calculate the image deformation as a reverse mapping. The problem can be stated "Which pixel coordinate in the source image do we sample for each pixel in the destination image?"
That's an except from this paper:
http://www.cs.princeton.edu/courses/archive/fall00/cs426/papers/beier92.pdf (pdf)
http://www.hammerhead.com/thad/morph.html (html)
The paper is about morphing, but the discussion of how to do the morphing should clear up the "forward / reverse mapping" issue.
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