A position of a first registration mark printed on a substrate during an earlier printing operation is detected. A second registration mark is printed on the substrate during a current printing operation at a position on the substrate relative to the first registration mark based on the detected position of the first registration mark and a correction factor. An alignment difference between the position of the first registration mark and the position of the second registration mark is measured. A new correction factor for a subsequent printing operation is calculated by weighting the measured alignment difference according to a difference between the measured alignment difference and a previous measured alignment difference.

An image forming apparatus, including: a light source including a plurality of light emitting points and configured to emit light beams; a photosensitive member configured to rotate in a rotation direction so that a latent image is formed thereon with the light beams; a rotary polygon mirror configured to rotate around a rotation axis and having a plurality of mirror faces each configured to deflect the light beams so that the photosensitive member is scanned with the light beams; a detector configured to detect temperature; and a correction unit configured to correct image data of an input image by using a deviation amount, in the rotation direction of the photosensitive member, of the light beams deflected by each of the plurality of mirror faces, wherein the correction unit obtains the deviation amount according to the temperature detected by the detector.

An image processing device includes: a compression unit that compresses original image data in units of a block; a first position correction unit that shifts positions of respective pixels contained in the original image data compressed by the compression unit such that the positions are shifted in a sub scanning direction; an expansion unit that expands the original image data shifted by the first position correction unit; and a second position correction unit that converts resolution of the original image data into higher resolution, and shifts the positions of the respective pixels of the converted original image data, wherein the first shift amount is a shift amount set in units of a shift corresponding to an integral multiple of the block, and the second shift amount is a shift amount set in units of a shift corresponding to one pixel with high resolution converted by the second position correction unit.

With this invention, color shifting correction is performed first based on shifting amount information indicating a shifting amount with respect to the scanning direction on an image carrier of each image forming unit, and halftone processing is then performed, thus suppressing generation of moiré due to the color shifting correction, and forming a high-quality image. To this end, an image forming engine has color shifting amount storage units C, M, Y, and K (black) which store actual shifting amounts with respect to ideal scan directions on image carriers C, M, Y, and K in image forming units C, M, Y, and K. Color shifting correction amount arithmetic units C, M, Y, and K calculate color shifting correction amounts for respective color components on the basis of the stored color shifting amounts. Color shifting correction units C, M, Y, and K perform color shifting correction by converting coordinates upon reading out image data from bitmap memories C, M, Y, and K on the basis of the calculated color shifting correction amounts, and then perform tone correction. Data after tone correction undergo halftone processing by halftone processors. C, M, Y, and K. PWM processors C, M, Y, and K generate PWM signals for scanning, and output them to exposure units C, M, Y, and K of the respective image forming units.

A redundantly printed security-enhanced document, printing method, and system for better ensuring that the meaning of the information imparted by variable indicia printed by redundant printing indicia on a document protected by a removable Scratch-Off Coating (SOC). By printing the variable indicia with multiple colors, redundancy and integrity of the intended indicia is achieved relative to the perception of human eye photoreceptor cones. The redundantly printed document, methods, and systems enhance the overall appearance of the redundantly printed document, and reduce possible consequences resulting from misprinted variable indicia.

A position of a first registration mark printed on a substrate during an earlier printing operation is detected. A second registration mark is printed on the substrate during a current printing operation at a position on the substrate relative to the first registration mark based on the detected position of the first registration mark and a correction factor. An alignment difference between the position of the first registration mark and the position of the second registration mark is measured. A new correction factor for a subsequent printing operation is calculated by weighting the measured alignment difference according to a difference between the measured alignment difference and a previous measured alignment difference.

Examples of an apparatus and method for use with a printing system are described herein. A correction to be applied to a printing system during print calibration is obtained. A distortion is applied to the correction. A relationship between an expected and measured output of the printing system is determined based on the print performed at least in part on the distorted correction. The printing system is calibrated on the basis of the determined correction.

An image forming apparatus includes: a scanning unit configured to form an electrostatic latent image on a photoconductor by scanning the photoconductor with one or more scanning beams in a main scanning direction based on an image signal, repetitively in a sub-scanning direction perpendicular to the main scanning direction; a generating unit configured to perform halftone processing on image data to generate the image signal; and a storage unit configured to store correction information. The correction information is set such that start positions of a plurality of scanning lines are linearly displaced to either a negative side or a positive side of the main scanning direction along the sub-scanning direction, in accordance with a direction of a first vector forming a smaller angle with the sub-scanning direction among two vectors in the halftone processing.

A method of digital printing is disclosed in which a digital image to be printed has at least one region having pixels comprising superpositioned layers of a first ink and a second ink. The method includes producing at least one sample print and calibrating misalignment of the superpositioned layers at a plurality of calibration locations on the sample print. The resultant misalignment data is provided to a morphing program to pre-deform the digital image to provide a modified digital image which compensates for misalignment during printing. The image is then printed using the modified digital image. An apparatus and a machine readable storage medium comprising instructions executable by a processor are also disclosed.

In one embodiment, an image forming apparatus includes an image region dividing portion which determines, within an image formable width, an image boundary position that matches with one of matrix boundaries corresponding to boundaries between dither matrices, and sets image adjustment regions. The image forming apparatus also includes a correction processing portion which uses common calibration data to determine imaginary adjustment regions positioned closest to the image adjustment regions, respectively, in a main scanning direction, and uses a correction amount for the determined imaginary adjustment region to correct the position in a sub-scanning direction, thereby reducing a color shift. The image region dividing portion determines the image boundary position by applying a rounding function to a value obtained by dividing the number of pixels constituting a width of the image adjustment region by the number of pixels in one cycle of the dither matrix in the main scanning direction.