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.

A system is disclosed. The system includes at least one physical memory device to store calibration logic and one or more processors coupled with the at least one physical memory device to execute the calibration logic to receive an image having a blended input color comprising a first primary color value and a second primary color value, generate blend weights for the blended input color based on the first primary color value and the second primary color value, receive a plurality of halftone designs corresponding to each of the first primary color value and the second primary color values and apply the blend weights and the plurality of halftone designs to the first primary color value and the second primary color value to generate a uniformity corrected halftone design associated with the first primary color value and a uniformity corrected halftone design associated with the second primary color value.

A system is disclosed. The system includes at least one physical memory device to store compensation logic and one or more processors coupled with the at least one physical memory device to execute the compensation logic to generate inverse transfer functions for each of a plurality of color planes to compensate for overlapping pel forming elements of adjacent printheads based on ink deposition functions for groups of pel forming elements including non-overlapping pel forming elements and the overlapping pel forming elements, wherein the inverse transfer functions transform output digital counts and the ink deposition functions represent output ink amount versus input digital count and generate compensated halftones for each of a plurality of color planes based on the inverse transfer functions.

The image processing apparatus of the present invention includes: a generation unit configured to generate a sharpness recovery amount for recovering degradation of a spatial frequency response from a target image; and a line width correction unit configured to perform line width correction processing for the target image based on the sharpness recovery amount, and the line width correction unit corrects a line width in accordance with a sign of a pixel whose absolute value of the sharpness recovery amount is large in a case where signs of the sharpness recovery amounts reverse between adjacent pixels of the target image.

A liquid discharge apparatus, a method of discharging liquid, and a recording medium storing a program for causing a computer to execute the method. The liquid discharge apparatus and the method includes obtaining image data to be printed, performing dithering to achieve masking and halftone processing on the image data to generate print data, and controlling movement of a discharge head and discharge of ink based on the print data. The controlling includes increasing a ratio of a number of ink dots continuously discharged onto a recording medium in a grayscale on a shadow side to a total number of ink dots discharged onto the recording medium in one-time scanning by the discharge head in one line to be greater than a ratio of a number of ink dots continuously discharged onto the recording medium in a grayscale on a highlight side to the total number of ink dots.

A method for correcting tone-level non-uniformities in a digital printing system includes printing a test target having a set of uniform test patches. The printed test target is automatically analyzed to determine tone-level errors as a function of cross-track position for each of the test patches. A tone-level correction function is determined and represented using a set of one-dimensional feature vectors which specifies tone-level corrections as a function of cross-track position, pixel value and time. Corrected image data is determined by using the tone-level correction function to determine a tone-level correction value for each image pixel responsive to the input pixel value, cross-track position and time. The corrected image data is printed using the digital printing system to provide a printed image with reduced tone-level errors.

Multiple first gradation values corresponding respectively to the multiple inks are quantized to generate multiple first quantized values indicating printing or non-printing of dots with the respective inks. In this case, multiple second gradation values corresponding respectively to multiple multinary colors expressible by combinations of overlapping of the multiple inks are generated based on the first gradation values. Next, the multiple second gradation values are quantized to generate multiple second quantized values indicating printing or non-printing of dots of the respective multinary colors. Then, the first quantized values corresponding to the inks to be overlapped one on top of another to express the multinary colors are generated based on the second quantized values corresponding respectively to the multiple multinary colors.

In an example method, a first dot pattern of shadow dots and second dot pattern of highlight dots is generated. The first dot pattern and second dot pattern include information to be encoded across the image. The first dot pattern and the second dot pattern are mapped to a corresponding subset of the greyscale source pixels, the greyscale source pixels corresponding to an image to be printed. A value of a greyscale pixel in the subset of the greyscale source pixels is modified based on a predetermined threshold pixel value. The value of the greyscale pixel is set to a highlight dot value in response to detecting that the predetermined threshold pixel value is exceeded or set to a shadow dot value in response to detecting that the predetermined threshold value is not exceeded. The image including the subset of pixels with modified values is printed.

An example operation method of an image forming apparatus includes forming a test image with respect to a pattern used for diagnosing an image-quality state of a printout output by the image forming apparatus, obtaining a test signal corresponding to the test image via a sensor of the image forming apparatus, obtaining image-quality state information indicating an image-quality state of the test image based on the test signal corresponding, identifying a type of a screen corresponding to halftone information indicating a resolution of the printout based on the image-quality state information, and performing a first image forming operation according to the type of the screen.

An image processing apparatus is equipped with: an image data receiving unit that receives image data; and a print data generating unit that generates multiple value data as print data by performing a halftone process on the image data and converting the image data into at least three values. The print data generating unit administers a halftone process that includes a density fluctuation suppressing process that results in the print data always including a zero value except for a case in which all of the pixels that constitute the image data are converted into a maximum value.