Image forming apparatus, color registration method of image forming apparatus, host apparatus, control method of host apparatus, and computer readable recording medium

1. A color registration method of an image forming apparatus, comprising:

printing a preset test pattern for color registration on a printing paper;

generating a scan image by scanning the printing paper on which is printed the preset test pattern for color registration;

detecting the printed test pattern for color registration from the scan image;

calculating location error values of respective colors, using the detected test pattern for color registration; and

performing the color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other with one of each of cyan C, magenta M, yellow Y and black K,

wherein the detecting the printed test pattern for color registration comprises detecting the printed test pattern for color registration by detecting the first color line from the scan image, and

the calculating comprises:

calculating median location values of respective color lines constituting the combined lines, and

calculating the location error values for respective colors using the calculated median location values of respective color lines,

wherein the calculating the median location values of respective color lines constituting the combined lines comprises:

calculating location values of a first edge and a second edge of the respective color lines;

calculating linear equations for the first and second edges, using the calculated location values of the first and second edges; and

calculating the median location values based on middle locations of a distance between the calculated linear equations of the first and second edges.

2. A color registration method of an image forming apparatus, comprising:

printing a preset test pattern for color registration on a printing paper;

generating a scan image by scanning the printing paper on which is printed the preset test pattern for color registration;

detecting the printed test pattern for color registration from the scan image;

calculating location error values of respective colors, using the detected test pattern for color registration; and

performing the color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other with one of each of cyan C, magenta M, yellow Y and black K,

wherein the detecting the printed test pattern for color registration comprises detecting the printed test pattern for color registration by detecting the first color line from the scan image, and

the calculating comprises:

calculating median location values of respective color lines constituting the combined lines, and

calculating the location error values for respective colors using the calculated median location values of respective color lines,

further comprising compensating distortion of the scan image using the median location values of the second color line at both ends, among the calculated median location values of the combined lines.

3. A color registration method of an image forming apparatus, comprising:

printing a preset test pattern for color registration on a printing paper;

generating a scan image by scanning the printing paper on which is printed the preset test pattern for color registration;

detecting the printed test pattern for color registration from the scan image;

calculating location error values of respective colors, using the detected test pattern for color registration; and

performing the color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other with one of each of cyan C, magenta M, yellow Y and black K,

wherein the detecting the printed test pattern for color registration comprises detecting the printed test pattern for color registration by detecting the first color line from the scan image, and

the calculating comprises:

calculating median location values of respective color lines constituting the combined lines, and

calculating the location error values for respective colors using the calculated median location values of respective color lines,

wherein the calculating the location error values comprises:

calculating an offset location error value that is an average moving distance of each of the third, fourth and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line;

calculating a phase location error value that is a difference of phase in the paper advancing direction of the third, fourth, and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line; and

calculating a skew location error value that is a difference of phase in the vertical direction to the paper advancing direction of the third, fourth and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line.

4. An image forming apparatus comprising:

an image forming unit that prints a preset test pattern for color registration on a printing paper;

a scanner that generates a scan image by scanning the printing paper on which is printed the test pattern for color registration; and

a controller that detects the printed test pattern for color registration from the scan image, calculates location error values of respective colors using the detected test pattern for color registration, and controls the image forming apparatus to perform color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other and each be one of cyan C, magenta M, yellow Y and black K,

wherein the controller detects the printed test pattern for color registration by detecting the first color line from the scan image, and

calculates median location values of respective color lines constituting the combined lines, and calculates the location error values for respective colors using the calculated median location values of respective color lines,

wherein the controller calculates location values of a first edge and a second edges of the respective color lines, calculates linear equations for the first and second edges, using the calculated location values of the first and second edges, and calculates the median location values based on middle locations of a distance between the calculated linear equations of the first and second edges.

5. An image forming apparatus comprising:

an image forming unit that prints a preset test pattern for color registration on a printing paper;

a scanner that generates a scan image by scanning the printing paper on which is printed the test pattern for color registration; and

a controller that detects the printed test pattern for color registration from the scan image, calculates location error values of respective colors using the detected test pattern for color registration, and controls the image forming apparatus to perform color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other and each be one of cyan C, magenta M, yellow Y and black K,

wherein the controller detects the printed test pattern for color registration by detecting the first color line from the scan image, and

calculates median location values of respective color lines constituting the combined lines, and calculates the location error values for respective colors using the calculated median location values of respective color lines,

wherein the controller compensates distortion of the scan image using the median location values of the second color line at both ends, among the calculated median location values of the combined lines.

6. An image forming apparatus comprising:

an image forming unit that prints a preset test pattern for color registration on a printing paper;

a scanner that generates a scan image by scanning the printing paper on which is printed the test pattern for color registration; and

a controller that detects the printed test pattern for color registration from the scan image, calculates location error values of respective colors using the detected test pattern for color registration, and controls the image forming apparatus to perform color registration using the calculated location error values of respective colors,

wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and

the first color is one of cyan C, magenta M, yellow Y, and black K, and

the second, third, fourth and fifth colors are different colors from each other and each be one of cyan C, magenta M, yellow Y and black K,

wherein the controller detects the printed test pattern for color registration by detecting the first color line from the scan image, and

calculates median location values of respective color lines constituting the combined lines, and calculates the location error values for respective colors using the calculated median location values of respective color lines,

wherein the controller calculates the location error values comprising:

an offset location error value that is an average moving distance of each of the third, fourth and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line;

a phase location error value that is a difference of phase in the paper advancing direction of the third, fourth, and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line; and

a skew location error value that is a difference of phase in the vertical direction to the paper advancing direction of the third, fourth and fifth color lines included in the combined lines with respect to the calculated median location value of the second color line.