Professionals of the graphics arts industry require color reproduction accuracy and consistency across a large and open set of media. For color critical applications this typically means the use of a color measurement instrument. All of these tasks can be carried out today with off-line measurement devices and the corresponding software, but such systems are not easy to use, not integrated into the workflow, and expensive. Embedding color measurement capabilities inside a printer tries to solve most of these issues. This paper explains the specifications of the embedded spectrophotometer of the HP Z-series DesingJet Large Format Printers, the challenges that were found during its development and the improvement of the colorimetric performance of the printers that are using it.