Produced according to your needs
A test chart it needs to fulfill certain requirements depending on the application. These requirements are defined by the camera/scanner system, the typical use-cases for the camera, the size of your lab, and the purpose of the target itself.
In order to meet these requirements we combine different material and production methods to get to the final chart. Here is a selection of the most popular printing processes we use:
Lithographic film and paper are especially known for highest resolution and are still used as standard material for most resolution, back focus and geometric calibration charts. Silver halide color and halftone materials are more difficult to handle and require more effort to maintain constant results. We sometimes use these materials for certain charts but the amount of work we need to put into production often leads to higher costs.
It is much easier to keep color and halftone inkjet prints constant. They require some calibration know-how and only special printers can be used due to the characteristics of the ink. The spectral reflection of typical inkjet prints is not constant over the full visible range of the light especially for grey patches which in some cameras may lead to color casts although the visible impression of the patches is neutral. The resolution of inkjet prints for the reproduction of fine detail is much lower than that of photographic material.
Offset or serigraphy
For targets which require mass production or need to be printed using specific colorants we use offset printing or serigraphy processes.
There are multiple additional processes that we use for our range of 270 different charts to always meet your quality expectations. Esser Test Charts are known worldwide for high quality.