What is the forward transform?
The forward transform is a matrix equation which relates the set of inter-electrode capacitance measurements C to the set of pixel permittivity values K. This transform assumes that the measured inter-electrode capacitances resulting from any arbitrary permittivity distribution K inside the sensor will be identical to those obtained by summing the component capacitance increases which occur when each pixel has its defined permittivity, with all other pixels values set to zero. This forward transform is defined in the equation below, where bold characters represent matrices : C = S.K C is an (M x 1) dimensioned matrix containing the set of M inter-electrode pair capacitances (where M is typically 66 for a 12-electrode sensor or 28 for an 8-electrode sensor for protocol 1). K is an (N x 1) dimensioned matrix (where N is 1024 for a 32 x 32 grid) containing the set of N pixel permittivity values which describe the permittivity distribution inside the sensor (the permittivity image). S is t
