A color imaging device includes a plurality of developer rolls with a common operating point, such as a common operating voltage. To determine the operating point, an acceptable range of color density is determined for each toner, the range being lighter and darker than an optimum color density for that toner. A search range is devised such that values within the range are examined relative to deviations from the optimum color density per each toner. The common operating point is selected as that having the lowest deviation per all toners. Also, if the common operating point corresponds to a color density darker than the acceptable range of color density for any toner, additional halftoning occurs compared to traditional halftoning, such as for continuous tones or solids. In this way, four color developer rolls can be operated from a single power supply, yet still provide acceptable color images.

A color imaging device includes a plurality of developer rolls with a common operating point, such as a common operating voltage. To determine the operating point, an acceptable range of color density is determined for each toner, the range being lighter and darker than an optimum color density for that toner. A search range is devised such that values within the range are examined relative to deviations from the optimum color density per each toner. The common operating point is selected as that having the lowest deviation per all toners. Also, if the common operating point corresponds to a color density darker than the acceptable range of color density for any toner, additional halftoning occurs compared to traditional halftoning, such as for continuous tones or solids. In this way, four color developer rolls can be operated from a single power supply, yet still provide acceptable color images.

An image forming apparatus, including: an image former; and a hardware processor which detects a density of an image formed by the image former, controls the image former to continuously perform image formation on a predetermined number of sheets and thereafter form a plurality of types of halftone test images on a sheet, determines whether an image defect is generated and determines a factor causing the image defect by analyzing densities of the plurality of types of test images, executes a recovery mode which is set for each of the factor when the image defect is determined to be generated, and controls the image former to form a charged test image which is formed by the charger charging the surface of the image carrier and an uncharged test image which is formed without charging of the surface of the image carrier by the charger.

An image forming apparatus comprising a printer unit that prints an image on a sheet using a line head in which a plurality of light emitting devices are arranged, and a storage that stores information regarding light amounts corresponding to the light emitting devices of the line head. The image forming apparatus generates a mask pattern based on the information regarding the light amounts obtained from the storage and a target light amount, and executes mask processing on halftone image data that is in positional correspondence with the light emitting devices, using the generated mask pattern.

In a case where image correction is performed to deal with a registration shift and a color shift in an electrophotographic image forming apparatus, it is made possible to obtain a sufficient correction effect even in a high-quality mode. The image forming apparatus having a first printing mode and a second printing mode includes: at least one controller, having at least one processor which executes instructions stored in at least one memory, at least one circuitry or a combination of the at least one processor and the at least one circuitries, being configured to: perform scan line changing processing to shift an image in units of pixels in a sub scanning direction at a predetermined scan line changing point in a main scanning direction in accordance with characteristics of a laser scan line; and correct a tone level value of a pixel of interest in an image after the scan line changing processing by referring to a tone level value of a pixel adjacent to the pixel of interest in a sub scanning direction.

In the image forming method, a halftone image is generated by performing halftone processing for an input image, a scanned image of a printed material on which on which the halftone image is printed is obtained, and a failure component of an image forming apparatus is identified based on a difference between the scanned image and the input image. In the generation, the halftone image is generated by representing a dot pattern of a halftone portion in a case where the input image is a test image for the failure diagnosis by a dot pattern whose frequency is relatively higher than that of a dot pattern that is applied to the halftone portion in a case where the input image is an image other than the test image.

In a case where image correction is performed to deal with a registration shift and a color shift in an electrophotographic image forming apparatus, it is made possible to obtain a sufficient correction effect even in a high-quality mode. The image forming apparatus having a first printing mode and a second printing mode includes: at least one controller, having at least one processor which executes instructions stored in at least one memory, at least one circuitry or a combination of the at least one processor and the at least one circuitries, being configured to: perform scan line changing processing to shift an image in units of pixels in a sub scanning direction at a predetermined scan line changing point in a main scanning direction in accordance with characteristics of a laser scan line; and correct a tone level value of a pixel of interest in an image after the scan line changing processing by referring to a tone level value of a pixel adjacent to the pixel of interest in a sub scanning direction.

An image forming apparatus includes an image forming unit configured to form an image with toner, a halftone processor configured to convert image data by performing halftone processing, a first determining unit configured to determine a first toner consumption amount for each page based on the image data, a second determining unit configured to determine a second toner consumption amount for each page based on the converted image data, a print percentage calculator configured to calculate a print percentage for one page based on the first toner consumption amount, a notifying unit configured to notify a remaining amount of the toner of the image forming unit based on the first toner consumption amount of a page of which the print percentage is larger than a threshold and the second toner consumption amount of a page of which the print percentage is equal to or smaller than the threshold.

An image forming apparatus, including: an image former; and a hardware processor which detects a density of an image formed by the image former, controls the image former to continuously perform image formation on a predetermined number of sheets and thereafter form a plurality of types of halftone test images on a sheet, determines whether an image defect is generated and determines a factor causing the image defect by analyzing densities of the plurality of types of test images, executes a recovery mode which is set for each of the factor when the image defect is determined to be generated, and controls the image former to form a charged test image which is formed by the charger charging the surface of the image carrier and an uncharged test image which is formed without charging of the surface of the image carrier by the charger.

An image forming apparatus is provided. The image forming apparatus includes an image forming unit containing a special recording material and circuitry configured to control the image forming unit to form a hardly visible image on a recording medium with the special recording material. The hardly visible image is formed of a halftone dot image comprising isolated dots in a number smaller than that of isolated dots forming a visible image having the same image area ratio as the hardly visible image.