Image processing apparatus, image processing method and image processing program product generating processing data having consistent pixel density

An image processing apparatus configured to generate printing image for printing document data having a first document resolution and a second document resolution equal to the first document resolution by a printer having a first print resolution in a main scanning direction and a second print resolution in a sub scanning direction different from the first print resolution, comprising:

• first processing means for generating first processing data of character data contained in the document data so that a proportion between a first resolution and a second resolution is equal to a proportion between the first print resolution and the second print resolution;
• second processing means for generating second processing data of image data contained in the document data having a same pixel density as a pixel density of the first processing data by changing the first document resolution and the second document resolution equal to the first document resolution, the pixel density being equal to the first print resolution times the second print resolution times a bit number of tone;
• and
• printing image generating means for generating printing data having the first print resolution and the first print resolution by synthesizing the first processing data and the second processing data, the printing image generating means generating the printing data having a same pixel density as the pixel densities of the first processing data and of the second processing data,
• wherein the second processing means makes the pixel density of the second processing data consistent with the pixel density of the first processing data by tone conversion of the image data, and performs the tone conversion of the image data so as to have a tone corresponding to a change of the changed first and second document resolutions.

An image processing method implemented by an image processing apparatus configured to generate a printing image for printing document data having a first document resolution and a second document resolution equal to the first document resolution by a printer having a first print resolution in a main scanning direction and a second print resolution in a sub scanning direction different from the first print resolution, comprising:

• a first step of generating first processing data of character data contained in the document data so that a proportion between a first resolution and a second resolution is equal to a proportion between the first print resolution and the second print resolution;
• a second step of generating second processing data of image data contained in the document data having a same pixel density as a pixel density of the first processing data by changing the first document resolution and the second document resolution equal to the first document resolution, the pixel density being equal to the first print resolution times the second print resolution times a bit number of tone;
• and
• a printing image generating step of generating printing data having the first print resolution and the first print resolution by synthesizing the first processing data and the second processing data, the printing image generating step generating the printing data having a same pixel density as the pixel densities of the first processing data and the second processing data,
• wherein the second processing step makes the pixel density of the second processing data consistent with the pixel density of the first processing data by tone conversion of the image data, and performs the tone conversion of the image data so as to have a tone corresponding to a change of the changed first and second document resolutions.