A method for reconstructing an image from emission data includes generating a compressed point-spread function matrix, generating an accumulated attenuation factor; and performing at least one image projection operation on an image matrix of the emission data using the compressed point-spread function matrix and the accumulated attenuation factor. A control process sends a message to an instance of an application instructing the application instance to divide the job into assignments for processing by various application instances. In the noise free case, each point in the plane is associated with a unique value of the \u03c4 vector. Electronics connected to each heater and sensor of their respective structures may provide processing to calculate the pressure or vacuum in the enclosure.