A method of screening a continuous-tone image is configured to produce an output image to be printed on a surface. The continuous-tone image comprises a plurality of pixels having respective corresponding intended print locations. The method includes selecting a first sequence comprising a subset of the plurality of intended print locations, the first sequence being selected based on properties of the plurality of intended print locations. For each intended print location in the first sequence, the method also includes identifying the corresponding pixel in the continuous-tone image to obtain a second sequence for an error diffusion process comprising the identified corresponding pixels in the continuous-tone image.

A quantized value for a pixel of interest in an input image is derived by using a predetermined threshold value matrix. Then, based on a pixel value group in a predetermined reference area including the pixel of interest in the input image and a threshold value group corresponding thereto, directionality of correction is determined. Further, based on the pixel value group and the threshold value group, whether or not the pixel of interest satisfies a predetermined condition for changing the quantized value is determined. Then, based on both the determination results, the quantized value is corrected.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

For a multi-pass printing, an image of a unit area is printed by M printing scans of M print regions of first and second nozzle arrays. Each of N pieces of column data is printed by a different printing scan. Ejection data for the first nozzle array is generated using a first mask pattern and ejection data for the second nozzle array is generated using a second mask pattern different from the first mask pattern, for each of the N pieces of column data. On that basis, the first mask pattern and the second mask pattern have a complementary relationship in each of the M print regions. Further, in each of the first mask pattern and the second mask pattern, a combination of print regions, of the M print regions, for printing dots at the same position on the print medium has a mutually complementary relationship.

For a multi-pass printing, an image of a unit area is printed by M printing scans of M print regions of first and second nozzle arrays. Each of N pieces of column data is printed by a different printing scan. Ejection data for the first nozzle array is generated using a first mask pattern and ejection data for the second nozzle array is generated using a second mask pattern different from the first mask pattern, for each of the N pieces of column data. On that basis, the first mask pattern and the second mask pattern have a complementary relationship in each of the M print regions. Further, in each of the first mask pattern and the second mask pattern, a combination of print regions, of the M print regions, for printing dots at the same position on the print medium has a mutually complementary relationship.

A printing system is disclosed. The printing system includes a printer to print image data to a medium. The printer includes a first pass channel including a first set of pel forming elements to print a first component of the image data and a second pass channel including a second set of pel forming elements to print a second component of the image data, wherein the first component of the image data and the second component of the image data occupy a same region on the print medium. The printing system also includes a print controller to perform uniformity compensation based on a combined compensation of the first pass channel and the second pass channel.

A printing system is disclosed. The printing system includes a printer to print image data to a medium. The printer includes a first pass channel including a first set of pel forming elements to print a first component of the image data and a second pass channel including a second set of pel forming elements to print a second component of the image data, wherein the first component of the image data and the second component of the image data occupy a same region on the print medium. The printing system also includes a print controller to perform uniformity compensation based on a combined compensation of the first pass channel and the second pass channel.

The present disclosure prevents a visible pattern corresponding to the pattern of a mask from being noticeable and enables more appropriate printing. A printing apparatus 10 performing printing by an inkjet scheme includes: an inkjet head 102; and a controller 20, configured to control the operation of a main scan driver 16 and a sub scan driver 18 to perform a main scanning operation multiple times on each position on a medium 50. In the main scanning operation, for at least part of ejection positions serving as ejection targets of ink droplets in the main scanning operation, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a mask for selecting part of the at least part of ejection positions. In the main scanning operation at one time, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a preset first mask. In the main scanning operation at another time different from the one time, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a second mask for selecting an ejection position in a pattern different from the first mask.

The present disclosure prevents a visible pattern corresponding to the pattern of a mask from being noticeable and enables more appropriate printing. A printing apparatus 10 performing printing by an inkjet scheme includes: an inkjet head 102; and a controller 20, configured to control the operation of a main scan driver 16 and a sub scan driver 18 to perform a main scanning operation multiple times on each position on a medium 50. In the main scanning operation, for at least part of ejection positions serving as ejection targets of ink droplets in the main scanning operation, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a mask for selecting part of the at least part of ejection positions. In the main scanning operation at one time, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a preset first mask. In the main scanning operation at another time different from the one time, the controller 20 causes the inkjet head 102 to eject an ink droplet in accordance with a second mask for selecting an ejection position in a pattern different from the first mask.