In order to achieve an ideal colorimetric calibration for CMYK (Cyan, Magenta, Yellow, and Black) printers, we propose a novel CMYK determination technique under the restrictions of a colorimetric match, use of the entire color gamut and a smooth gradation of each primary color. The algorithm proposed here includes the following steps: (1) Obtain the two extreme conditions for CMYK combinations to be able to utilize the entire CMYK gamut, namely Maximum Black technique and Minimum Black, (2) Determine an arbitrary black amount between the two conditions, (3) Apply a smoothing technique for the black amount in a uniform color space, (4) Determine the remaining colors, CMY, for colorimetric match. An iterative smoothing technique in a uniform color space is introduced to obtain visually "smoothed" black gradations. The gradation quality for each primary color is evaluated with a hypothetical unstable printer. The smoothed CMYK technique eliminates sudden changes for each primary color, so that a printer using this technique becomes robust against a change of characteristic curves of the printer such as dot gain.