Ink jet printing apparatus

1. An ink jet printing apparatus comprising:

a generation unit configured to generate printing target image data including an image page, on which ink droplet numbers are recorded for respective pixels, according to a print resolution for every page and every color component;

a printing unit configured to perform printing on a printing paper by discharging ink, having ink droplet numbers corresponding to the respective pixels with a first maximum ink droplet number determined based on the printing paper as an upper limit, to positions on the printing paper corresponding to the respective pixels in the printing target image data;

a conveying speed determination unit configured to determine a conveying speed of the printing paper during printing processing performed by the printing unit, based on the first maximum ink droplet number;

an ink droplet number distribution calculation unit configured to calculate a distribution of the ink droplet numbers for every page and every color component when the printing target image data is generated by the generation unit;

a pixel number determination unit configured to determine whether or not pixel numbers corresponding to the ink droplet numbers are equal to or smaller than a predetermined threshold value in all color components and all pages in order of a greater ink droplet number from the first maximum ink droplet number, based on the distribution of the ink droplet numbers of all the pages calculated by the ink droplet number distribution calculation unit;

a maximum ink droplet number determination unit configured to determine, as a second maximum ink droplet number, a greatest ink droplet number among ink droplet numbers which are ink droplet numbers equal to or smaller than the first maximum ink droplet number and of which pixel numbers are not equal to or less than the predetermined threshold value, based on a determination result obtained by the pixel number determination unit;

a difference time calculation unit configured to calculate a difference time obtained by subtracting a time when printing of all the pages of the printing paper is completed at a conveying speed corresponding to the second maximum ink droplet number from a time when printing of all the pages of the printing paper is completed at a conveying speed corresponding to the first maximum ink droplet number;

a reproduction unit configured to associate the second maximum ink droplet number with an allocation target pixel, which is a pixel corresponding to an ink droplet number that is greater than the second maximum ink droplet number and of which the pixel number is equal to or greater than a predetermined value, within the printing target image data, and allocating a difference value between an ink droplet number corresponding to the allocation target pixel and the second maximum ink droplet number to pixels around the allocation target pixel, to reproduce the printing target image data;

a difference time determination unit configured to determine whether or not a reproduction time required for reproducing the printing target image data by the reproduction unit is smaller than the difference time calculated by the difference time calculation unit; and

a control unit configured to, when it is determined by the difference time determination unit that the reproduction time is smaller than the difference time, make the reproduction unit perform reproduction processing and controlling the printing unit and the conveying speed determination unit based on the second maximum ink droplet number.

2. The ink jet printing apparatus according to claim 1 ,

wherein the generation unit generates the printing target image data based on different print resolutions according to the color components,

wherein the printing unit discharges the ink, having the ink droplet numbers corresponding to the respective pixels, to positions on the printing paper corresponding to the respective pixels in the printing target image data, for every color component, with a maximum ink droplet number determined based on the printing paper and the print resolution as an upper limit, to perform printing on the printing paper, and

wherein the conveying speed determination unit determines the conveying speed of the printing paper during the printing processing performed by the printing unit, using the maximum ink droplet number, which is greatest among maximum ink droplet numbers determined for every color component, as the maximum ink droplet number.

3. The ink jet printing apparatus according to claim 2 ,

wherein a page number of an image page, the size of the printing paper to be printed on, and the print resolution are included in the printing target image data,

wherein the inkjet printing apparatus further comprises:

a storage unit configured to store therein a prediction time table showing a time predicted to be required for reproducing the printing target image data by the reproduction unit according to the page number of the image page, the size of the printing paper, and the print resolution, and

wherein the difference time determination unit determines a time corresponding to the page number, the size of the printing paper, and the print resolution, which are included in the printing target image data, as the reproduction time, with reference to the prediction time table.

4. The ink jet printing apparatus according to claim 3 , further comprising:

a prediction time table generation unit configured to generate the prediction time table by classifying a time required for performing the reproduction processing by the reproduction unit, according to the page number of the image page, the size of the printing paper, and the print resolution after the processing of the ink droplet number distribution calculation unit, the pixel number determination unit, and the maximum ink droplet number determination unit is performed on a plurality of pieces of printing target image data in advance,

wherein the prediction time table generated by the prediction time table generation unit is stored in the storage unit.

5. The ink jet printing apparatus according to claim 1 ,

wherein a page number of an image page, the size of the printing paper to be printed on, and the print resolution are included in the printing target image data,

wherein the inkjet printing apparatus further comprises:

a storage unit configured to store therein a prediction time table showing a time predicted to be required for reproducing the printing target image data by the reproduction unit according to the page number of the image page, the size of the printing paper, and the print resolution, and

wherein the difference time determination unit determines a time corresponding to the page number, the size of the printing paper, and the print resolution, which are included in the printing target image data, as the reproduction time, with reference to the prediction time table.

6. The ink jet printing apparatus according to claim 5 , further comprising:

a prediction time table generation unit configured to generate the prediction time table by classifying a time required for performing the reproduction processing by the reproduction unit, according to the page number of the image page, the size of the printing paper, and the print resolution after the processing of the ink droplet number distribution calculation unit, the pixel number determination unit, and the maximum ink droplet number determination unit is performed on a plurality of pieces of printing target image data in advance,

wherein the prediction time table generated by the prediction time table generation unit is stored in the storage unit.