A method and a measuring device are proposed for controlling the color application of a printing press (10) using at least one ink-feeding device (20) on the basis of spectral reflectance values of printed surface elements (24) on a print substrate (22), which are distinguished in that measured spectral reflectance values are converted into corrected spectral reflectance values. The method and/or the measuring device can be advantageously used in a printing system having a printing press (10), to implement a control on the basis of polarized spectral reflectance values, in particular for a detector (28) which measures unpolarized spectral reflectance values.