1. A method for estimating color measurements of color samples: comprising: printing a color sample based on input data; measuring a color of the printed color sample with an in-line spectral sensor at a first temperature; estimating a color of the printed color sample which would be output by a reference spectral sensor at a second temperature, the estimation being based on a thermochromatic model which represents relationships between measured colors of printed color samples on the in-line spectral sensor at the first temperature and the reference spectral sensor at the second temperature, the reference spectral sensor being a different type of sensor from the in-line spectral sensor such that a set of printed spot color samples generate different measured colors at the second temperature on the in-line spectral sensor from the reference spectral sensor.