Clustered dot-screen design method, a device to perform the clustered dot-screen design method based on human vision and printer model characteristics, and an image-forming apparatus to output binary images on a designed screen

A method of determining a clustered-dot screen to form an original image using a predetermined image forming apparatus model, the method comprising:

• designing a plurality of binary patterns to represent a plurality of different gray level image pixels using cluster center position information, human vision characteristics, and the predetermined image forming apparatus model;
• and
• storing the plurality of binary patterns.

A clustered-dot screen design device based on human vision characteristics and printer model characteristics, comprising:

• a cluster center location design unit to determine positions of a plurality of clustered-dot centers using a predetermined method;
• and
• a screen design unit to design a screen using a modified Direct Binary Search (DBS) algorithm according to position information of the cluster centers, the human vision characteristics, and the printer model characteristics.

An image-forming apparatus, comprising:

• a memory unit to store screens each having a plurality of cluster centers, black sub-dots grown nearest to the cluster centers, and white sub-dots grown farthest from the cluster centers;
• and
• an image-processing unit to compare the screens stored in the memory unit with an input image and to output a binary image.

An image processing device usable with an image forming apparatus to determine a clustered-dot screen to form an original image using a model of the image forming apparatus, the image processing device comprising:

• a cluster center unit to determine a plurality of cluster centers for a screen;
• and
• a screen design unit to select a sub-dot growth sequence about the plurality of cluster centers, to measure a difference between a visual perception of the original image and a print out of the original image that is output according to the selected sub-dot growth sequence, and to adjust the selected sub-dot growth sequence one or more times to minimize the difference between the visual perception and the print out to determine an optimal sub-dot growth sequence for the image forming apparatus model.

An image forming apparatus to determine a clustered-dot screen to form an original image using model information thereof, the apparatus comprising:

• a screen design device to design a plurality of binary patterns to represent a plurality of different gray level image pixels using cluster center position information, human vision characteristics, and the predetermined image forming apparatus model;
• and
• a storage unit to store the plurality of binary patterns.

A computer readable medium containing executable code to perform a clustered-dot screen design method based on human vision characteristics and printer model characteristics, the medium comprising:

• a first executable code to determine positions of a plurality of clustered-dot centers using a predetermined method;
• and
• a second executable code to design a screen by growing specific sub-dots about the plurality of cluster centers using a predetermined algorithm according to position information of the plurality of cluster centers, the human vision characteristics, and the printer model characteristics.