Abstract: In an example, a method includes ejecting a drop of printing fluid from a nozzle of a printhead into a drop detection zone. An indication of detection of the drop within the drop detection zone may be determined and, based on the indication of detection of the drop, an indication of a position of the printhead may be provided.

Abstract: The present disclosure relates to methods and devices for estimating an amount of print material available in a print material reservoir of a printer. In an example there is disclosed a method comprising determining a first value for an amount of print material contained within a print material container. The method may further comprise determining, after a printhead maintenance event comprising ejecting print material into a spittoon, a second value for the amount of print material contained within the print material container. The method may further comprise estimating, based on a difference between the first value and the second value, an amount of print material remaining in the print material reservoir.

Abstract: In an example, a surface inspection apparatus includes a light source to illuminate a portion of a surface in a print apparatus, a light detection apparatus and processing circuitry. The light detection apparatus may receive diffusely reflected light and specularly reflected light from the portion of the surface, and may comprise a detection element for detecting the specularly reflected light. The processing circuitry may comprise a comparison module to determine a relationship between an intensity of the detected diffusely reflected light and the detected specularly reflected light and a quality module to evaluate if the surface meets a quality criterion based on the relationship.

Abstract: In an example, a surface inspection apparatus includes a light source to illuminate a portion of a surface in a print apparatus, a light detection apparatus and processing circuitry. The light detection apparatus may receive diffusely reflected light and specularly reflected light from the portion of the surface, and may comprise a detection element for detecting the specularly reflected light. The processing circuitry may comprise a comparison module to determine a relationship between an intensity of the detected diffusely reflected light and the detected specularly reflected light and a quality module to evaluate if the surface meets a quality criterion based on the relationship.