The image processing system includes a image input device (3) for generating an image of a workpiece to be extracted and for generating a corresponding analogue signal. An ADC (8) converts the analogue signal from the image input device into a digital signal with a predetermined gradation. A grey image storage device (9) stores image data provided as digital signals. A histogram generating device (10) generates a density histogram in response to the stored image data. A device (11) registers a selected density region for at least a section of the workpiece to be extracted on the basis of the density histogram. A further device extracts the workpiece on the basis of the selected density region.
