Image processor and image processing method
View Patent ↗A screening output density corrector of an image processor corrects output densities of a plurality of types of dotted pattern data stored in a screening data storage upon printing. A dotted image data generator uses a plurality of types of the dotted pattern data subjected to the output density correction for performing screening processing to each of images, the images being represented by the continuous tone image data. Consequently, the dotted image data generator generates dotted image data of the images with the corrected output density. Accordingly, output density correction is made not to the continuous tone image data but to the dotted pattern data. Consequently, uniformity of the discharge characteristic (the number of ink droplets) is obtainable upon printing with different types of dotted pattern data. This allows prevention of unevenness in printing through the screening processing based on a plurality of types of dotted pattern data.
1. An image processor for generating dotted image data by performing screening processing for forming dots to continuous tone image data, the image processor comprising:
a screening data storage device storing a plurality of types of dotted pattern data for use in the screening processing to each of a plurality of images represented by the continuous tone image data;
a screening output density correcting device performing output density correction to the plurality of types of dotted pattern data when the continuous tone image data is processed for printing; and
a dotted image data generating device generating dotted image data with a corrected output density from the continuous tone image data by performing the screening processing to each of the plurality of images represented by the continuous tone image data using the plurality of types of dotted pattern data subjected to the output density correction.
2. The image processor according to claim 1 , wherein
the screening output density correcting device multiplies a threshold of each of pixels set in the dotted pattern data by a nozzle shading coefficient.
3. The image processor according to claim 2 , wherein
the screening output density correcting device performs the correction to dotted pattern data corresponding to only a part of the continuous tone image data while shifting the dotted pattern data over the continuous tone image data entirely.
4. The image processor according to claim 1 , wherein
the screening output density correcting device performs the correction to dotted pattern data corresponding to only a part of the continuous tone image data while shifting the dotted pattern data over the continuous tone image data entirely.
5. An image processing method for generating dotted image data by screening processing for forming dots to continuous tone data, the method comprising:
performing screening output density correction to a plurality of types of dotted pattern data for use in the screening processing upon printing to each of a plurality of images represented by the continuous tone image data; and
generating dotted image data with a corrected output density from the continuous tone image data by performing the screening processing to each of the plurality of images represented by the continuous tone image data using the plurality of types of dotted pattern data subjected to the output density correction.
6. The image processing method according to claim 5 , wherein
the performing screening output density correction includes multiplying a threshold of each of pixels set in the dotted pattern data by a nozzle shading coefficient.
7. The image processing method according to claim 6 , wherein
the performing screening output density correction includes correcting dotted pattern data corresponding to only a part of the continuous tone image data while the dotted pattern data is shifted over the continuous tone image data entirely.
8. The image processing method according to claim 5 , wherein
the performing screening output density correction includes correcting dotted pattern data corresponding to only a part of the continuous tone image data while the dotted pattern data is shifted over the continuous tone image data entirely.