Canon Kabushiki Kaisha

Senichi Saito

Akitoshi Yamada

Fumitaka Goto

Nobutaka Miyake

Junichi Nakagawa

Tomokazu Ishikawa

Ryosuke Iguchi

Hidetsugu Kagawa

Mitsuhiro Ono

Shinjiro Hori

Tohru Ikeda

Kouta Murasawa

Hiromitsu Akiba

Provided is an image recording apparatus, including: a recording unit recording an image on a recording sheet; a conveying unit conveying a plurality of recording sheets in an overlapping state to the recording unit; and a setting unit setting an overlapping amount so that the image is prevented from being printed on a region of a predetermined range which includes a boundary between an overlapping portion, in which a subsequent sheet and a preceding sheet overlap each other, and a non-overlapping portion, in which the subsequent sheet and the preceding sheet do not overlap each other.

Image recording apparatus, method of controlling image recording apparatus, and storage medium

In low-resolution processing (reduction processing) in which input image data is separated into character print data and image print data to generate print data of lower resolution than that of the input image data, if a plurality of pixels is simply reduction-processed to one pixel, color of a color image surrounding a character may change. In an image processing method, calculation for performing reduction processing so that the plurality of pixels in the input image data corresponds to one pixel in the print data is performed as follows. A ratio of using a pixel value of a character attribute pixel in the calculation is set to 0, or set smaller than a ratio of using a pixel value of an image attribute pixel. As a result, a change in the color of the color image surrounding the character can be prevented.

Image processing method and image processing apparatus

Because the ejection state of a printing element in a printing apparatus may vary at all times, an inspection item for inspecting a printed image may be set in consideration of the ejection state of the printing element. An inspection item for inspecting a printed image may be set based on information including a temperature characteristic of a printing head and a state of ink such as an elapsed time from the last ejection. This allows image inspection that matches with variations in the ejection state of the printing element.

Image processing apparatus and image processing method which adjusts image inspection to match variations in the ejection state of the printing element

Image ink data is generated which represents the absence of ejection of ink corresponding to pixels for which text ink data represents the ejection of ink.

Image processing apparatus for performing image processing for recording text and images, and image processing method for performing image processing for recording text and images

Provided is a quantization processing method using dither patterns that make it possible to obtain a dot array having excellent dispersibility even in the case of a single color or mixed color inks. For this purpose, first and second dither patterns are prepared in order to respectively quantize multivalued data for a first ink to different pieces of binary data, respectively. Also, third and fourth dither patterns are prepared in order to respectively quantize multivalued data for a second ink to different pieces of binary data. Further, on the basis of a combination of the multivalued data on the first ink and the multivalued data on the second ink, a quantization unit for the first ink, and a quantization unit for the second ink are determined.

Image processing apparatus and method using different dither patterns for different inks and selecting a quantization process for each ink

In order to print a unit area of a print medium by a first printing scan and a second printing scan, dither patterns are formed which can control the arrangement of dots on the print medium without adverse effects of density unevenness and graininess, that are caused by printing position displacement. Regarding first and second dither patterns, information indicating whether or not a threshold is already set to a reference pixel and one or more pixels around the reference pixel in the first dither pattern is obtained for cases where each pixel in the first dither pattern is the reference pixel. A pixel in the second dither pattern to which a predetermined pixel is to be set is determined based on the obtained information. The first and second dither patterns formed in the above manner are associated with the first printing scan and the second printing scan, respectively.

Dither pattern forming method and dither pattern

Area information is obtained with respect to a specified color and nozzle position having color unevenness. Then, coordinate information indicating a nozzle position corresponding to the above area information is obtained in a printing head or nozzle array corresponding to an ink color relating to the specified color information. Next, the number of candidate correction values or candidate patches is obtained on the basis of nozzle coordinates obtained corresponding to the area, by referring to a table. In this table, for example, the number of candidate correction values is small at a nozzle position where an effect due to the variations of nozzle ejection characteristics such as a nozzle ejection volume is small and a change direction is constant, and the number of candidate correction values is large at a nozzle position where an effect due to variations of nozzle ejection characteristics is large.

Image processing apparatus, printing apparatus, and image processing method

Provided is a dither pattern generation method so that a dot arrangement having excellent dispersibility can be obtained in low-gradation areas for single colors and for mixed colors. The dither pattern generation method generates dot patterns for low-gradation areas having threshold values 1 to S so that high dispersibility is obtained in a cyan dot pattern and a magenta dot pattern, and so that in a combined dot pattern made by combining these dot patterns there are no overlapping pixels. The dither pattern generation method then sets threshold values for a cyan dither pattern and a magenta dither pattern based on these generated dot patterns.

Generating and using blue noise dither patterns with high value thresholds positioned for a high dot concentration ratio

An image processing apparatus includes a generation unit; wherein a first dither pattern and a second dither pattern have same threshold values that are set for same pixels in a first gradation range, and have different threshold values that are set for same pixels in a second gradation range that exceeds the first gradation range; and the generation unit sets a first threshold value for forming dots of the first dither pattern, and generates a first binary data according to whether or not a threshold value corresponding to a target pixel of the first dither pattern is included in the first threshold value, and sets a second threshold value for forming dots of the second dither pattern, and generates a second binary data according to whether or not a threshold value corresponding to a target pixel of the second dither pattern is included in the second threshold value.

Image processing apparatus and method setting thresholds of dither patterns based on density range and generating binary data depending on thresholds of target pixels

Provided is an image processing apparatus that can accurately and efficiently reduce color unevenness that occurs in a color image, which is formed by color mixture of a plurality of different types of inks, due to a variation in ejection characteristic among nozzles. The inks are respectively ejected from the nozzle arrays to print patches; regions where color correction for test color images should be performed are specified; a different types of color correction processing for color signals corresponding to the color correction regions are performed to print color correction patches; a color correction patch to be used is selected; on the basis of selected color correction processing, a table parameter corresponding to a nozzle is formed; when the plurality of color correction patches are formed, only correction candidate values having larger color differences than a predetermined threshold value in a uniform color space are generated for color signals.

Image processing apparatus, image processing method, and printer

Nozzles in a print head are arrayed in a density of 600 dpi. Moreover, a dither matrix has a size of 16 pixels&#xd7;16 pixels in 600 dpi. The dither matrix is repeatedly used. In the meantime, each of rectangles represents an HS processing unit. WHS=3 pixels. As a consequence, the relationship of a least common multiple below is established in a nozzle array direction: 3&#xd7;WD=16&#xd7;WHS. In this case, the cycle of interference unevenness can be prolonged to the least common multiple between WD and WHS, that is, 48 pixels (3WD). In this manner, the size of the dither matrix is not an integral multiple of the HS processing unit width, so that the cycle of interference unevenness can be prolonged more than the size of the dither matrix. Thus, the interference unevenness can be hardly recognized.

One dither mask having a highest spacial frequency is selected from a plurality of dither masks. Next, a granularity is obtained with reference to a table based on the selected dither mask and an ejection amount level per area. Moreover, a difference in granularity between adjacent areas is calculated with respect to all of the areas. A maximum value is obtained out of the obtained differences in granularity, and then, the maximum difference in granularity is compared with a determination threshold. When the maximum difference in granularity is the threshold or greater, it is determined whether or not a dither mask having a spacial frequency lower than that of the selected dither mask is stored in a memory. When there are dither masks having lower spacial frequencies, a dither mask having a spacial frequency lower by one level than that of the selected dither mask is selected.

An image processing apparatus is provided that is capable of very accurately and efficiently reducing uneven color caused by variation in ejection characteristics among nozzles that eject ink and that occurs in a color image that is formed by mixing a plurality of different kinds of ink. A patch is printed by ejected ink from a plurality of nozzles, a region is specified so as to perform color correction in a test color image that is printed on a printing medium, a plurality of different color correction processing is performed on color signals that correspond to a color correction region, a plurality of color correction patches are printed, a color correction patch to be used is selected from among the plurality of different color correction patches and table parameters that correspond to the nozzles are created based on the selected color correction processing.

In the present invention, a first calculation unit calculates, based on image data obtained by reading with a reading unit a plurality of patches formed on a printing medium by a plurality of nozzle regions constituting nozzle array of a printing head, respective color specification values of a plurality of correction regions corresponding to a plurality of nozzle regions constituting the nozzle array. Then, a target value setting unit sets, based on the calculated color specification values of the plurality of correction regions, a target color specification value of the patch. Further, a second calculation unit calculates a difference between each of the color specification values of the plurality of correction regions and the target color specification value as a correction amount. After that, based on the correction amount calculated, image data corresponding to an image printed by each of the plurality of nozzle regions are corrected.

Inkjet printer and image processor for correcting image data based on color specification values and a target color specification value

When printing an image using a plurality of inks, color unevenness caused by variations in ejection characteristics among nozzles is corrected at suitable timings in accordance with change in the color unevenness over time, and favorable image output without noticeably color unevenness is maintained. For this purpose, parameters are prepared, for colors formed by combinations of at least two colors of ink, the parameters being determined so as to reduce differences in coloration on a print medium caused by individual variations in the ejection characteristics of a plurality of nozzles. When printing, a first color signal included in individual pixels is corrected for a second color signal by using the parameters. Information regarding the ejection volume characteristics of a plurality of nozzles is acquired as appropriate, and by estimating changes in coloration from this information, suitable timings for overwriting such parameters are determined.

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Funabashi, Japan

Senichi Saito