Document processing system, image forming apparatus, document processing method and computer readable medium for generating a synthetic image

1. A document processing system comprising:

a generator that generates a document image to be printed;

a memory that stores document images for a plurality of pages, the document images generated by the generator in print processing and being double-sided or continuing for multiple pages;

a number of pages setting unit that sets page intervals at which document images are acquired for a set number of pages;

a document image acquiring unit that acquires document images for the set number of pages set by the number of pages setting unit at the set page intervals;

an arithmetic unit that performs an AND operation on document images acquired by the document image acquiring unit from the document images stored in the memory; and

a display controller that causes a display device to display a synthetic image obtained by the AND operation by the arithmetic unit,

wherein:

the document images generated by the generator in print processing correspond to a plurality of documents,

the page intervals set by the number of pages setting unit correspond to a number of pages in each document in the plurality of documents, and

the document images acquired by the document image acquiring unit are document images acquired every nth page from the document images stored in the memory, where n=the page intervals set by the number of pages setting unit.

2. The document processing system according to claim 1 , wherein, upon receipt of an instruction to display the synthetic image, the display controller acquires the synthetic image from the arithmetic unit and causes the display device to display the synthetic image thus acquired.

3. The document processing system according to claim 1 , wherein the AND operation performed by the arithmetic unit comprises:

when dots at a same position in each of the document images for the number of specific pages have a same pixel value, a pixel value of a dot at the same position in the synthetic image is set at the same pixel value; and

when the dots at the same position in each of the document images for the number of specific pages have different pixel values, the pixel value of the dot at the same position in the synthetic image is set to a blank value.

4. An image forming apparatus comprising:

an image forming unit that forms a document image on a medium by using an image forming material in print processing;

a generator that generates the document image in the print processing;

a memory that stores document images for a plurality of pages, the document images generated by the generator and being double-sided or continuing for multiple pages;

a number of pages setting unit that sets page intervals at which document images are acquired for a set number of pages;

a document image acquiring unit that acquires document images for the set number of pages set by the number of pages setting unit at the set page intervals;

an arithmetic unit that performs an AND operation on document images acquired by the document image acquiring unit from the document images stored in the memory;

a display that displays a synthetic image obtained by the AND operation by the arithmetic unit; and

an output unit that causes the image forming unit to form and output the synthetic image obtained by the AND operation by the arithmetic unit,

wherein:

the document images generated by the generator in print processing correspond to a plurality of documents,

the page intervals set by the number of pages setting unit correspond to a number of pages in each document in the plurality of documents, and

the document images acquired by the document image acquiring unit are document images acquired every nth page from the document images stored in the memory, where n=the page intervals set by the number of pages setting unit.

5. The image forming apparatus according to claim 4 , wherein the image forming unit forms the synthetic image on a medium apart from the print processing, the synthetic image obtained by the AND operation by the arithmetic unit.

6. The image forming apparatus according to claim 4 , wherein the image forming unit forms a document image on a medium apart from the print processing as a sample image, the document image generated most recently among the document images targeted for the AND operation by the arithmetic unit.

7. A document processing method for a document processing system comprising:

generating document images to be printed;

storing the document images for a plurality of pages, the document images generated in print processing and being double-sided or continuing for multiple pages;

setting page intervals at which document images are acquired for a set number of pages;

acquiring document images for the set number of pages at the set page intervals;

performing an AND operation on document images acquired from the document images thus stored; and

causing a display device to display a synthetic image obtained by the AND operation,

wherein:

the document images generated in print processing correspond to a plurality of documents,

the set page intervals correspond to a number of pages in each document in the plurality of documents, and

the acquired document images are document images acquired every nth page from the stored document images, where n=the set page intervals.

8. A non-transitory computer readable medium storing a program that causes a computer to execute a process for controlling an image forming apparatus, the process comprising:

generating document images to be printed;

storing the document images in a storage for a plurality of pages, the document images generated in print processing and being double-sided or continuing for multiple pages;

setting page intervals at which document images are acquired for a set number of pages;

acquiring document images for the set number of pages at the set page intervals;

performing an AND operation on document images acquired from the document images stored in the storage; and

causing a display device to display a synthetic image obtained by the AND operation,

wherein:

the document images generated in print processing correspond to a plurality of documents,

the set page intervals correspond to a number of pages in each document in the plurality of documents, and

the acquired document images are document images acquired every nth page from the stored document images, where n=the set page intervals.