A print data editing device performs editing print data such that when dots constituting an input image represented by the print data are compared by units of columns before and after performing the editing, a coincidence is maximized when an image of each column in the input image after the editing is the same position as an image of the corresponding column in the input image before the editing or is shifted by a corresponding shift amount relative to the image of the corresponding column in the input image before the editing and an editing condition is met. The editing condition includes that an absolute value of at least one shift amount is one dot or greater, an absolute difference value for any two neighboring columns is one dot or less, and at least one absolute difference value for all possible combinations of two columns is less than one dot.

A print data editing device is configured to perform: editing print data such that when dots constituting an input image represented by the print data are compared by units of columns before and after the editing, a coincidence is maximized when an image of each column in the input image after the editing is the same position as an image of the corresponding column in the input image before the editing or is shifted by a corresponding shift amount in a sub-scanning direction relative to the image of the corresponding column in the input image before the editing. An absolute value of at least one of shift amounts for columns in the input image after the editing is one dot or greater. An absolute difference value for any two neighboring columns in a main scanning direction in the input image after the editing is one dot or less.

An image forming apparatus includes a photoconductor, a light source, and circuitry that receives: first image data including first pixels each indicating image density or one of turning on and off the light source; and tag data indicating an attribute of each first pixels. The circuitry sets specific data to identify a first target pixel subjected to change out of the first pixels, converts the first image data into second image data having a higher resolution than that of the first image data, and controls the light source according to the second image data to form an image. In conversion, the circuitry identifies a second target pixel corresponding to the first target pixel out of second pixels of the second image data according to the specific data and the tag data, and changes the second target pixel into a pixel to turn on the light source.

An image processing method generates image data of an image made up of a plurality of dots and having resolution in a first direction and resolution in a second direction. The second direction intersects the first direction. The resolution in the first direction is different from the resolution in the second direction. The image processing method includes performing contour portion correction including adding a dot at a correction target pixel, the correction target pixel being a pixel adjacent to a step-like contour portion in the image, and when a dot is arranged at a pixel adjacent to a pixel of interest adjacent to the correction target pixel, deleting the dot at the pixel of interest.

An image forming apparatus that forms an image according to light emitted from a light source is provided. The image forming apparatus includes: a first image processor that performs image processing on image data having a first resolution and outputs the resulting image data; a resolution converter that acquires the image data having the first resolution output from the first image processor and converts the image data to image data having a second resolution that is higher than the first resolution; a modulation signal generator that modulates the image data having the second resolution according to a clock signal to thereby generate a modulation signal; a light source driver that drives the light source according to the modulation signal; and a second image processor that performs image processing on the image data having the second resolution to be modulated to the modulation signal.

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 print data editing device performs editing print data such that when dots constituting an input image represented by the print data are compared by units of columns before and after performing the editing, a coincidence is maximized when an image of each column in the input image after the editing is the same position as an image of the corresponding column in the input image before the editing or is shifted by a corresponding shift amount relative to the image of the corresponding column in the input image before the editing and an editing condition is met. The editing condition includes that an absolute value of at least one shift amount is one dot or greater, an absolute difference value for any two neighboring columns is one dot or less, and at least one absolute difference value for all possible combinations of two columns is less than one dot.

A print data editing device is configured to perform: editing print data such that when dots constituting an input image represented by the print data are compared by units of columns before and after the editing, a coincidence is maximized when an image of each column in the input image after the editing is the same position as an image of the corresponding column in the input image before the editing or is shifted by a corresponding shift amount in a sub-scanning direction relative to the image of the corresponding column in the input image before the editing. An absolute value of at least one of shift amounts for columns in the input image after the editing is one dot or greater. An absolute difference value for any two neighboring columns in a main scanning direction in the input image after the editing is one dot or less.

An image forming apparatus includes a process unit that includes a photosensitive drum, a charger, and a developing device, a print head, a first sub-scanning color shift correction circuit, a sub-scanning resolution conversion circuit, and a second sub-scanning color shift correction circuit. The first sub-scanning color shift correction circuit reads image data from a page memory and corrects the read image data in a first line period based on a first color shift parameter set in advance. The sub-scanning resolution conversion circuit converts the image data corrected by the first sub-scanning color shift correction circuit into image data of a second line period. The second sub-scanning color shift correction circuit corrects the image data converted by the sub-scanning resolution conversion circuit in the second line period based on a second color shift parameter set in advance and outputs the corrected image data to the print head.

Provided is a thermal printer achieving high repeatability of one dot even in an image having a large change in a density and capable of printing a printing material having high sharpness. A thermal printer includes: an image data extension processing unit generating extended image data having pixels in which the number of pixels in a feed direction of a paper sheet is extended; a printing data correction processing unit correcting a density of at least one extended pixel based on a change in a density of the extended pixels in the extended image data in the feed direction or a change in a density of pixels in the image data before extended in the feed direction; and a printing unit printing the image on the paper sheet based on the extended image data in which the density of the at least one extended pixel is corrected.