Abstract: A slicing machines includes a control system having a camera (6) which views a cut face (5) of a product being sliced. Image data from the camera (6) is processed to determined a parameter characteristic of the cut face (5). The step of processing the image data includes classifying the image data by comparison with an intensity threshold which is varied automatically in accordance with the populations of data in the different classes. A control signal is generated to control the operation of the slicing machine in accordance with the determined parameter.In a preferred example, the determined parameter depends on the linear density of the cut face and the control signal varies the thickness of the slices in order to produce a slice having a desired weight.