A color measurement instrument, such as a spectrophotometer, measures the reflected light from a color patch and stores the measurement as a numeric value. The procedure for measuring a page of patches depends on the instrument.

Some instruments have a self-calibration feature to check the correct functioning of the instrument. For example, the instrument may be calibrated by checking its ability to measure a known color sample accurately. If self-calibration is available, you must calibrate the instrument before proceeding to measure a page.

Handheld instruments require that you follow instructions to place the page and measure each row of patches on the page. Automatic instruments measure each row and advance to the next row without user interaction. Some instruments also position the page automatically.