System and method for image rotation

• US 20050073695A1
• Filed: 09/22/2004
• Published: 04/07/2005
• Est. Priority Date: 09/26/2003
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Caffee, Brian R., Mohabir, Daniel A., Schlachter, Lisa M., Guy, James P., Lapietra, Dawn M., Nacman, Aron
• Granted Patent: US 7,894,094 B2
• Time in Patent Office: Days
• US Class Current: 358/1.200
• CPC Class Codes: G06T 3/606 by memory addressing or mapping
• CPC Class Codes: H04N 1/3877 Image rotation

Abstract

A system and method to provide 180-degree rotation of image data at full throughput. The system includes a memory access controller that writes bursts of image data into a rotation buffer. The image data is then read out of the rotation buffer in the reverse order from which it was written to thereby accomplish rotation. By alternating the position in the rotation buffer in which the image data is written such that an image is either written into the buffer from top and read from the bottom or written into the buffer from the bottom and read out from the top, a one page rotation buffer of can be used to concurrently process two pages.

Claims

1. A method of processing image data, comprising:

receiving first image data corresponding to an image from a first page;

receiving second image data corresponding to an image from a second page;

writing the first image data into a memory according to a first fill order;

reading the first image data from the memory in an order reverse of the fill order; and

writing the second image data into the memory according to a second fill order, the second fill order;

wherein the steps of writing the second image data into the memory and reading the first image data from the memory alternately write bursts of the second image data to and read bursts of the first image data from the memory.

2. The method of processing image data according to claim 1 wherein the step of writing the first image data places bursts of two predefined sizes into the memory block.

3. The method of processing image data according to claim 1 wherein the memory is defined by a set of addresses bounded by first address and a second address;

the first fill order includes a series of addresses beginning with a start address near the first address and ending with a stop address near the second address; and

the second fill order includes a series of addresses beginning at an address near the second address and ending at an address near the first address.

4. The method of processing image data according to claim 3 wherein the first fill order sequentially fills the memory from the start address to the stop address.

5. A rotation processor for processing image data to generate rotated image data, comprising:

a scanline buffer receiving image data;

a rotation buffer; and

a direct memory access controller, the direct memory access controller operating

to read bursts of image data corresponding to a first page from the scanline buffer and write the bursts of image data corresponding to the first page into the rotation buffer according to a fill order and

to alternate reading bursts of image data corresponding to the first page from the rotation buffer in an order reverse of the fill order and writing bursts of image data corresponding to the second page read from the scanline buffer into the rotation buffer in an order reverse of the fill order.

6. The rotation processor according to claim 5, further comprising a rotation memory block for receiving image data read from the rotation buffer by the direct memory access controller.

7. The rotation processor according to claim 6, further comprising:

a second scanline buffer; and

an input multiplexer having an input to receive the image data from the first system, the input multiplexer directing the image data received from the first system to one of the first and second scanline buffers.

8. The rotation processor according to claim 7, further comprising a non-rotation memory block, wherein the direct memory access controller further operates to control the flow of image data from the second scanline buffer to the non-rotation memory block.

9. A system for generating duplex copies from hardcopy originals, comprising:

a scanning device capturing scanned image data from a document, the scanning device having a first scanning station for capturing image data from a first side of the document and a second scanning station for capturing image data from a second side of the document;

a rotation processor generating rotated image data, the rotation processor including

a scanline buffer receiving the scanned image,

a rotation buffer, and

a direct memory access controller, the direct memory access controller operating to write the second side data into a rotation buffer in a fill order, and reading the second side data from the rotation buffer in an order reverse of the fill order; and

an image output terminal connected to receive the rotated image data.

10. The system according to claim 9, wherein the rotation processor further comprises:

a non-rotation memory; and

an input multiplexer having an input to receive the scanned image data, the input multiplexer directing the scanned image data to one of the a scanline buffer and the non-rotation memory.

11. A method of processing image data to generate rotated image data, the method comprising:

receiving image data from a scanning device, the image data including first side data and second side data;

writing bursts of the first side data into a rotation buffer according to a fill order; and

alternating reading a burst of the first side data from the rotation buffer and writing a burst of the second side data into the rotation buffer;

wherein the step of alternating reading a burst of the first side data and writing a burst of the second side data, reads the burst of the first side data and writes the burst of the second side data in an order reverse of the fill order.

12. The method of processing image data according to claim 11 wherein the first side data is written into the rotation buffer using bursts of at least two predefined sizes.

13. The method of processing image data according to claim 12 wherein the second side data is written into the rotation buffer using bursts of two predefined sizes.

14. The method of processing image data according to claim 11 wherein the fill order sequentially fills the rotation buffer.

15. The method of processing image data according to claim 11 further comprising feeding the burst of the first side data through a last in first out buffer.