A phase frequency detector circuit compares two clock signals and generates a number of outputs to indicate a phase difference between these two clock signals. The DCR in the present invention can be produced by obtaining crude DCR by directly carbonylating ruthenium through allowing a ruthenium salt and carbon monoxide to react with each other and by purifying the crude DCR by a sublimation method. The color pixels of the image data are counted in a device independent space and the total color pixel count of the image data to be output in a device dependent space is estimated. The LNT is monitored to determine the need for regeneration or desulfurization.