A control method for a printing apparatus includes: an image defect detecting step of detecting an ejection curve amount of a nozzle in an inkjet head and an image defect from a recordable medium on a surface of which an image is recorded by an image recording part provided with the inkjet head having a plurality of nozzles, and a stamp step of attaching a stamp indicating presence of the image defect on the recordable medium by a stamping device in a case where the image defect is detected, the stamp step differentiating an attachment form of the stamp by the stamping device in accordance with a magnitude of the ejection curve amount of the nozzle.

A first light emitter emits light toward a sheet. A first light receiver receives first reflected light from the sheet. A second light emitter is arranged downstream of the first light emitter in a conveyance direction of the sheet and emits light toward the sheet. A second light receiver receives second reflected light from the sheet. A measuring section measures first and second received light quantities of the first reflected light and the second reflected light. A moisture content calculator calculates a change in a moisture content of the ink in the sheet based on a difference between first and second moisture contents. The first moisture content is based on the first received light quantity and the second moisture content is based on the second received light quantity. A curling amount calculator calculates a curling amount of the sheet based on the change in the moisture content.

The position information includes first position information about a position, at a first timing, of a droplet ejected from a first nozzle, which is one of the plurality of nozzles, and traveling in air, and second position information about a position, at the first timing, of a droplet ejected from a second nozzle, which is one of the plurality of nozzles N and is different from the first nozzle, and traveling in air.

An ink discharge operation adjustment method includes the following, recording a halftone image in which the ink is discharged to form a predetermined halftone pattern and a solid image in which the ink completely covers a surface of the recording medium; obtaining a first reading result by a reader reading a non-recording region in which an image is not recorded on a recording medium; obtaining a second reading result of the halftone image and the solid image so that a difference of an elapsed time from a start of the curing to the reading is within a predetermined reference difference; obtaining coverage rate information based on the reading results; and performing setting regarding adjustment of a droplet amount of the ink based on the coverage rate information.

An image recording apparatus includes a recording head including a plurality of nozzles from which ink is ejected, a memory, and one or more hardware processors coupled to the recording head and the memory. The one or more hardware processors are configured to: determine, for each of the plurality of nozzles, whether a position of the corresponding nozzle is a position to eject ink; determine whether a successive ejection operation is necessary for a nozzle out of the plurality of nozzles, whose position is determined as the position to eject ink; and cause ink to be successively ejected at the position to eject ink at a predetermined successive ejection frequency from the nozzle that is determined to have the necessity of the successive ejection operation.

A method for assessing the condition and improving the printing quality of printing nozzles in printheads of an inkjet printing machine includes printing a nozzle test chart formed of a specific number of horizontal rows of equidistant vertical lines printed periodically underneath one another, with only every n.sup.th printing nozzle contributing to the test chart in every row of the test chart and n corresponding to a different number between one and the specific number of horizontal rows, recording and digitizing the test chart and analyzing the test chart regarding the condition of the contributing nozzles by using a computer. The nozzles printing horizontal lines between the horizontal rows complementing the equidistant vertical lines to form quadrangular objects used by the computer to analyze the condition of the contributing nozzles. Measures are taken to improve the printing quality of the nozzles depending on the condition of the contributing nozzles.

The invention relates to a method for detecting a failing ejection unit in an array of ejection units during printing of a digital image with liquid ink in a printer wherein a medium is transported relative to the array. The printed image is captured to density values on print positions of the printed image. The invented method comprises a step of adapting a halftone mask that is used in preparation of the digital image, such that from a variation in the image density around the line shaped defect the exact nozzle number associated with the failing ejection unit can be determined.

An inkjet printer includes: a print execution unit that executes printing; and a controller that controls the print execution unit. The controller is configured to: determine whether a type of ink supplied by the ink supply unit is changed; determine whether to use a residual ink which is ink before change remaining in the ink flow path in response to be determined that the type of the ink is changed; control the print execution unit to execute new printing using the residual ink in response to be determined to use the residual ink for the printing; and execute a discarding process for discarding the residual ink before the new printing is performed in response to be determined to not use the residual ink for the printing.

The present disclosure provides processing for performing highly-accurate density nonuniformity correction while saving the number of patches. A chart generation unit obtains measurement data of the latest test chart. A patch tone calculation unit obtains an output characteristic expressing measurement values for input tone values based on the obtained measurement data and calculates selected tone values to be used as the input tone values for a test chart from the obtained output characteristic. A chart image generation unit generates the test chart by using the calculated selected tone values as the input tone values and not using at least one initial tone value as the input tone value.

A recording device includes a recording head in which a plurality of nozzle rows are arranged in a predetermined direction that include a first nozzle row including a plurality of nozzles for ejecting ink having a predetermined color, and a second nozzle row including a plurality of nozzles for ejecting ink having an identical color to the predetermined color, and a control unit configured to control ejection of ink by the nozzle, wherein the control unit, when a test pattern for an inspection of a missing dot due to an ejecting defect of the nozzle is recorded on a recording medium, records a dot pattern, that is an individual element that forms the test pattern, so that ink ejected from a nozzle of the first nozzle row, and ink ejected from a nozzle of the second nozzle row overlap.