1. A method for decoupling or correcting measured parameters in a touch-based user interface using at least one computational processor, the method comprising: receiving tactile image data responsive to data generated from a user touch to a user touch interface comprising a sensor array; processing the tactile image data with a series of operations to produce a first processed data vector, the series of operations comprising at least one rotation operation, the first processed data vector comprising a plurality of numerical values responsive to data generated from the user touch interface; and further processing a proper subset of the variables comprised by the first processed data vector, the further processing comprising a piecewise-affine computational operation on the proper subset of the variables comprised by the first processed data vector, the piecewise-affine operation using at least one provided linear transformation and at least one provided offset vector, the at least one provided linear transformation selected from a plurality of possible linear transformations and the at least one provided offset vector selected from a plurality of possible offset vectors; wherein the selection of the linear transformation from the plurality of possible linear transformations and the selection of the offset vector from the plurality of possible offset vectors is determined by conditional tests made on at least one of the numerical values comprised by the first processed data vector, and wherein the further processing produces a second processed data vector comprising a plurality of numerical values responsive to data generated from the user touch interface.