A process for producing a composite oxide catalyst to be used for gas phase oxidation of an olefin or unsaturated aldehyde with molecular oxygen to produce the corresponding unsaturated aldehyde andor unsaturated carboxylic acid, which has a uniform constant high performance, in an industrial scale and efficiently and constantly, is presented. The roller assembly includes a roller pin and a crushing roller. Readout points of the raw magnetic resonance data are displaced by the displacement value, and image data are reconstructed from the displaced raw magnetic resonance data. The ultrasound system further includes a processing unit coupled to the sensing unit. Each ink inlet is in fluid communication with a common ink reservoir.