Misregistration judging method, registration mark for color printing, color slippage detection mark, color slippage correction chart, color registration correction chart color slippage detection method color slippage correction

A registration mark for color printing comprising:

• a mark of a reference color;
• and
• a mark of a color for measurement which is centered at a same position as the mark of a reference color, and has a figure which is similar to that of the mark of a reference color.

A color registration correction chart comprising:

• a registration mark for color printing which is printed on a sheet of paper, the registration mark for color printing including
• a mark of a reference color, and
• a mark of a color for measurement which is centered at a same position as the mark of a reference color, and has a figure which is similar to that of the mark of a reference color.

A color slippage detection mark comprising:

• dots of printing colors alternately arranged as repetition of a unit of a predetermined number of dots.

A color image forming apparatus comprising:

• storage means for storing a color slippage detection mark including dots of printing colors alternately arranged as repetition of a unit of a predetermined number of dots;
• and
• control means for controlling the operation of reading the printing data of the color slippage detection mark from the storage means and printing it on a sheet of paper according to an instruction.

A color slippage correction chart comprising:

• color slippage detection marks of several different types formed by means of dots of printing colors alternately arranged as repetition of a unit of a predetermined number of dots and shifting the printing colors in a direction by the smallest unit of correction.

A color slippage correction method comprising the steps of:

• printing color slippage correction charts of printing colors on a sheet of paper, each including color slippage detection marks of several different types formed by means of dots of printing colors alternately arranged as repetition of a unit of a predetermined number of dots and shifting the printing colors in a direction by the smallest unit of correction;
• and
• measuring color attributes for the color slippage detection mark of each printing color of the color slippage correction chart printed on the sheet of paper, selecting a color slippage detection mark having color attributes close to those of the related target color and correcting the color slippage of the printing color according to the color slippage detection mark.

A color image forming apparatus comprising:

• storage means for storing printing data on color slippage correction charts of printing colors, each including color slippage detection marks of several different types formed by means of dots of printing colors alternately arranged as repetition of a unit of a predetermined number of dots and shifting the printing colors in a direction by the smallest unit of correction;
• and
• control means for controlling the operation of reading out the printing data on the color slippage correction chart from the storage means and printing them on a sheet of paper according to an instruction.