High resolution printing

A method for ejecting ink droplets onto a print medium to print a pattern of dots which forms a printed image, where the dots have a diameter d, the method comprising the steps of:

• ejecting ink droplets to form a first checkerboard array of dots comprising parallel rows of dots, the dots within each row being aligned in a second direction which is perpendicular to a first direction, the dots having a spacing between centers which is substantially equivalent to 2d, each row of dots being offset in the first and second directions from each adjacent row by a distance substantially equivalent to d, where no dot in the first array overlaps another dot in the first array;
• ejecting ink droplets to form a second checkerboard array of dots having the same relative spacings between dots as the first checkerboard array, the second checkerboard array being offset from the first checkerboard array in the second direction by a distance less than 2d, where no dot in the second array overlaps another dot in the second array;
• ejecting ink droplets to form a third checkerboard array of dots having the same relative spacings between dots as the first checkerboard array, the third checkerboard array being offset from the second checkerboard array in the second direction by a distance less than 2d, and the third checkerboard array being offset from the second checkerboard array in the first direction by a distance less than d, where no dot in the third array overlaps another dot in the third array;
• and
• ejecting ink droplets to form a fourth checkerboard array of dots having the same relative spacings between dots as the first checkerboard array, the fourth checkerboard array being offset from the third checkerboard array in the second direction by a distance less than 2d, where no dot in the fourth array overlaps another dot in the fourth array.

A method for ejecting ink droplets from an array of ink jet nozzles onto a print medium to print a pattern of dots which forms a printed image, where the nozzles are aligned in a first direction and have a center-to-center spacing in the first direction of d, the method comprising the steps of:

• ejecting ink droplets to form a first array of dots comprising parallel columns of dots aligned in the first direction and parallel rows of dots aligned in a second direction which is orthogonal to the first direction, where adjacent dots in each column have a center-to-center spacing in the first direction substantially equivalent to 2d, where adjacent dots in each row have a center-to-center spacing in the second direction substantially equivalent to 2d, and where no dot in the first array overlaps another dot in the first array;
• ejecting ink droplets to form a second array of dots having the same relative spacings between dots as the first array, the second array being offset from the first array in the first and second directions by a distance substantially equivalent to {fraction (d/2+L )}, where no dot in the second array overlaps another dot in the second array;
• ejecting ink droplets to form a third array of dots having the same relative spacings between dots as the first array, the third array being offset from the second array in the first direction by a distance substantially equivalent to {fraction (d/2+L )}, where no dot in the third array overlaps another dot in the third array;
• and
• ejecting ink droplets to form a fourth array of dots having the same relative spacings between dots as the first array, the fourth array being offset from the third array in the first and second directions by a distance substantially equivalent to {fraction (d/2+L )}, where no dot in the fourth array overlaps another dot in the fourth array.

A method for formatting image data representing an image to be printed by ejecting ink droplets from an array of ink jet nozzles in an ink jet print head, where the nozzles are aligned in a first direction and have a center-to-center spacing in the first direction of d, the method comprising the steps of:

• receiving image data represented by a rectangular matrix of pixels, the matrix having a resolution of substantially equivalent to {fraction (2+L /d)} pixels per unit length in the first direction and {fraction (2+L /d)} pixels per unit length in a second direction which is orthogonal to the first direction, the matrix of pixels comprising alternating even and odd columns and alternating even and odd rows of pixels;
• and
• separating the image data into four arrays of pixels, each array having a resolution of substantially equivalent to {fraction (1+L /d)} pixels per unit length in the first direction and {fraction (1+L /d)} pixels per unit length in the second direction, the separating comprising the steps of:
• forming a first array of pixels comprising pixels disposed in both the even columns and the even rows of the matrix of pixels;
• forming a second array of pixels comprising pixels disposed in both the odd columns and the odd rows of the matrix of pixels;
• forming a third array of pixels comprising pixels disposed in both the odd columns and the even rows of the matrix of pixels;
• and
• forming a fourth array of pixels comprising pixels disposed in both the even columns and the odd rows of the matrix of pixels.