Did You Know? Reference Charts Age Too
Objective image quality measurements rely on dependable references. Yet while cameras, lighting systems, and test setups are regularly checked, one important factor is often overlooked: the test chart. Reference charts age over time and the aging process can affect the validity of measurement results. You can find the recommended replacement date on the back of your test chart.
When evaluating camera systems, most attention is focused on the device under test. Engineers monitor the devices performance and the quality of the images they capture, image quality, calibrate test setups, and ensure reproducible measurement conditions. What is often overlooked, however, is that the reference itself changes over time.
Color test charts in particular are exposed to environmental influences throughout their lifetime that degrade their quality. Ultraviolet radiation from sunlight and high-intensity light sources can affect the properties of the color patches. These changes typically occur gradually and are often invisible to the naked eye. Nevertheless, they can become relevant for precise measurements because the reference values on which evaluations are based may drift over time.
For this reason, all reflective Image Engineering serial charts include a recommended replacement date on the back of the chart. In addition, every chart datasheet specifies the recommended service life. A service life of three years is recommended for black-and-white charts, while color charts have a recommended service life of two years.
Proper handling can help preserve chart performance for longer. Color charts should be protected from unnecessary light exposure and stored in their protective folder or carrying case when not in use. Unlike many measurement devices, post-production recalibration of color charts is generally not possible.
Reliable image quality measurements begin with a reliable reference. That is why it is worth occasionally checking the recommended service life of the test charts used in your lab. Maintaining up-to-date references is a simple but important step toward ensuring long-term measurement reproducibility and comparability.
Is Your Test Chart Still Within Its Recommended Service Life?
Check the recommended replacement date on your chart or refer to the corresponding datasheet. For reflective charts, the recommended replacement date can be found on the label located on the back of the chart. Transmissive charts do not carry such a label, but their recommended service life is specified in the corresponding datasheets, which are available for download on the respective product pages.
Replacing aged references at the appropriate time is an important step toward maintaining reliable and reproducible measurement results.
