Method and devices for calibrating optical density reflective color fluids to be deposited on substrate are disclosed. Some methods comprise depositing a quantity of a keying color fluid on a first region of the substrate; applying a voltage level to a reflective color fluid application device; depositing, in response to the voltage level applied, a quantity of reflective color fluid on the first region of the substrate and on a second region of the substrate; performing reflectance measurements of the first region and of the second region; performing optical density calculations as a function of the reflectance measurements; varying the voltage level applied to the reflective color fluid application device in response to said optical density calculation until the optical density calculation is within a calibrated range of optical densities.

Method and devices for calibrating optical density reflective color fluids to be deposited on substrate are disclosed. Some methods comprise depositing a quantity of a keying color fluid on a first region of the substrate; applying a voltage level to a reflective color fluid application device; depositing, in response to the voltage level applied, a quantity of reflective color fluid on the first region of the substrate and on a second region of the substrate; performing reflectance measurements of the first region and of the second region; performing optical density calculations as a function of the reflectance measurements; varying the voltage level applied to the reflective color fluid application device in response to said optical density calculation until the optical density calculation is within a calibrated range of optical densities.

Fuel sampling systems are disclosed. In one embodiment, a fuel sampling system includes an optical capture device and an analysis computing device that stores logic for implementing an evaluation sequence. During the evaluation sequence, the analysis computing device performs at least the following: receive a captured image from the optical capture device, identify areas of highest contrast in the captured image, and determine if the areas of highest contrast define a ring. If the areas of highest contrast define a ring, evaluate a contrast ratio between the ring and areas outside of the ring, and determine if the captured image reflects a fuel sample that exceeds a predetermined limit of propensity for settling. If so, indicate that the captured image reflects a fuel sample that is not acceptable. Otherwise, indicate that the captured image reflects a fuel sample that is acceptable.

Fuel sampling systems are disclosed. In one embodiment, a fuel sampling system includes an optical capture device and an analysis computing device that stores logic for implementing an evaluation sequence. During the evaluation sequence, the analysis computing device performs at least the following: receive a captured image from the optical capture device, identify areas of highest contrast in the captured image, and determine if the areas of highest contrast define a ring. If the areas of highest contrast define a ring, evaluate a contrast ratio between the ring and areas outside of the ring, and determine if the captured image reflects a fuel sample that exceeds a predetermined limit of propensity for settling. If so, indicate that the captured image reflects a fuel sample that is not acceptable. Otherwise, indicate that the captured image reflects a fuel sample that is acceptable.