An inkjet recording device includes a hardware processor. The hardware processor: performs, for respective recording heads of a recorder, setting relevant to adjustment of an amount of ink to be discharged from nozzle groups; based on ink discharge amount information on a distribution of ink discharge amounts that are discharged from the nozzle groups based on image data, performs the setting such that at each joint in the nozzle groups, a difference between representative values of the ink discharge amounts of the nozzle groups satisfies a predetermined continuity condition, and a representative value of the ink discharge amounts of the nozzle groups satisfies a predetermined discharge amount condition; and adjusts at least a part of the setting such that a difference between a maximum value and a minimum value of the ink discharge amounts of the nozzle groups reduces.

In an inkjet recording apparatus, a control section forms a test chart in which a plurality of lines, each extending along the recording-medium width direction, are drawn arranged along the recording-medium conveyance direction by making the ink ejection nozzles eject ink, while gradually changing either ink ejection timing with respect to each of the ink ejection nozzles or a recording-medium conveyance speed. Furthermore, the control section checks for, and corrects, pixel deviation in the recording-medium conveyance direction based on the test chart.

When sub-images are sequentially transferred and connected together to form a larger image than would be possible with a single transfer operation, the occurrence of a color change in the overlapping region of the sub-images is suppressed and the width of the overlapping region is reduced as much as possible. Color image data are divided into image data of two sub-images containing an overlapping region and having edges that coincide for each color ink transferred to paper. Color values of the color image data in the overlapping region are converted by using a color conversion factor group created in advance for each position on the overlapping region so as to cancel out a color change that occurs in the overlapping region when the sub-images are transferred with one overlapping the other. The image data of the sub-images are corrected by adjusting converted color values in the overlapping region by using a correction factor for print density at each position on the overlapping region. A color image is formed by sequentially transferring the sub-images in accordance with corrected image data thereof so that the sub-images overlap at the overlapping region.

In accordance with an embodiment, a thermal printer comprises a first thermal head, a first sensor and a control section. The first thermal head prints a first mark on a first surface of an image receiving medium. The first sensor detects a printing density of the first mark. The control section determines whether or not the printing density of the first mark is in a predetermined range, and adjusts the printing density by the first thermal head in the predetermined range in response to determining that the printing density of the first mark is out of the predetermined range.

Each area in a test pattern for performing color shift correction is recorded by a discharge port at an edge portion in many times of scanning and by a discharge port other than the discharge port at the edge portion in fewer times of scanning.

An image processor performs: determining a dot value indicating a dot formation state, the determining including: in a case where a target pixel is not an edge pixel and a first dot forming condition is satisfied, setting the dot value to a value indicating forming a first dot; and in a case where a second dot forming condition is satisfied, setting the dot value to a value indicating forming a second dot; determining a distribution error value, the determining including: in the case where the target pixel is not the edge pixel and the first dot forming condition is satisfied, setting the distribution error value to a value corresponding to a density of the first dot; and in the case where the second dot forming condition is satisfied, setting the distribution error value to a smaller value than a value corresponding to a density of the second dot.

When sub-images are sequentially transferred and connected together to form a larger image than would be possible with a single transfer operation, the occurrence of a color change in the overlapping region of the sub-images is suppressed and the width of the overlapping region is reduced as much as possible. Color image data are divided into image data of two sub-images containing an overlapping region and having edges that coincide for each color ink transferred to paper. Color values of the color image data in the overlapping region are converted by using a color conversion factor group created in advance for each position on the overlapping region so as to cancel out a color change that occurs in the overlapping region when the sub-images are transferred with one overlapping the other. The image data of the sub-images are corrected by adjusting converted color values in the overlapping region by using a correction factor for print density at each position on the overlapping region. A color image is formed by sequentially transferring the sub-images in accordance with corrected image data thereof so that the sub-images overlap at the overlapping region.

In accordance with an embodiment, a thermal printer comprises a first thermal head, a first sensor and a control section. The first thermal head prints a first mark on a first surface of an image receiving medium. The first sensor detects a printing density of the first mark. The control section determines whether or not the printing density of the first mark is in a predetermined range, and adjusts the printing density by the first thermal head in the predetermined range in response to determining that the printing density of the first mark is out of the predetermined range.

A control method for printer, the control method includes: controlling a first group of heating units of a printing head to output first printing energy to form printing dots with a first density on a printing medium; and controlling a second group of heating units of the printing head to continue outputting second printing energy to form printing dots with a second density on the printing medium, wherein the second group of heating units consists of heating units need to implement printing energy compensation in the first group of heating units. By means of the control method, the printing densities of the printing dots corresponding to the heating units need to implement printing energy compensation are improved, and the problem of non-uniform printing density of each printing dot caused by non-uniform pressure exerted on the printing platen by the printing head can be effectively solved.

A printing system including a printing device and a higher-level device to transmit image data to the printing device, wherein the higher-level device includes a correction value calculation portion to calculate a correction value for correcting the image data based on a density of each line of the image data, and a transmitter to add the correction value calculated by the correction value calculation portion to the image data for each line and transmit the image data and the correction value to the printing device, and wherein the printing device includes a storage unit to associate the correction value with the image data received from the higher-level device for each line and to store the image data and the correction value, and a printing unit to perform printing by changing a time for energizing each heating element in a thermal head based on the correction value stored in the storage unit.