Methods and devices for enhancing edges of a graphic object

Patent metadata

Field	Value
Publication number	US-9973654-B1
Application number	US-201715478262-A
Country	US
Kind code	B1
Filing date	Apr 4, 2017
Priority date	Apr 4, 2017
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

The present disclosure discloses methods and systems (a multi-function device or a digital printer) having capabilities for an object enhancement. In an example, the MFD includes a digital front end module to detect edge of the object and direction of the edge. Following the detection of the edge, the digital front end module classify the pixels of the edge into two categories, for example, which define that whether the edge pixels are created by black-to-white transition or white-to-black transition. Based on the classification of the edge pixels, the digital front end module performs the object enhancement either in black-to-white transition or in white-to-black transition.

First claim

What is claimed is:

1. A method for enhancing an object present in an input image, the method comprising:
receiving a print job, wherein the print job comprising the input image;
converting the input image into a digital bitmap image comprised of an array of pixels, wherein each pixel being assigned with a pixel value representing printing information;
based on the pixel value, detecting edge pixels of the object present in the input image;
performing enhancement on the edge pixels of the object present in the input image, wherein for each edge pixel:
forming a window around the edge pixel with a height and a width of predefined pixels;
calculating a sum of active pixels in columns and a sum of active pixels in rows for the window;
based on the calculation, determining direction of edge of the object present in the window, and determining whether the edge pixel is formed due to black-to-white transition or white-to-black transition; and
based on the determination, performing the enhancement on the edge pixel in the window;
generating an output image based on the enhancement performed on the edge pixels of the object; and
printing the generated output image.

2. The method of claim 1 , wherein the receiving comprising receiving the print job in a page description language (PDL) file from a user device.

3. The method of claim 1 , wherein the converting comprising:
decomposing the print job using commands and information stored in the print job to extract the input image; and
performing raster image processing on the input image to convert the input image into the digital bitmap image.

4. The method of claim 1 , wherein the forming comprising forming the window around the edge pixel with a height and width of 9 pixels.

5. The method of claim 4 , further comprising splitting the window into nine 3×3 kernels.

6. The method of claim 5 , further comprising:
calculating the sum of active pixels in columns of the window;
determining whether the sum of active pixels in columns is greater than a predefined threshold; and
performing enhancement in vertical direction when the sum of active pixels in columns is greater than the predefined threshold.

7. The method of claim 6 , wherein the predefined threshold is 7.

8. The method of claim 6 , wherein the performing enhancement comprising:
determining a sum of active pixels being assigned with a pixel value greater than 100 in a given 3×3 kernel;
performing the enhancement from white-to-black transition in the vertical direction when the determined sum of active pixels being assigned with a pixel value greater than 100 is more than 4 active pixels in the given 3×3 kernel; or
performing the enhancement from black-to-white transition in the vertical direction when the determined sum of active pixels being assigned with a pixel value greater than 100 is more than 4 active pixels in the given 3×3 kernel.

9. The method of claim 5 , further comprising:
calculating the sum of active pixels in rows of the window;
determining whether the sum of active pixels in rows is greater than a predefined threshold; and
performing enhancement in horizontal direction when the sum of active pixels in rows is greater than the predefined threshold.

10. The method of claim 9 , wherein the predefined threshold is 7.

11. The method of claim 9 , wherein the performing enhancement comprising:
determining a sum of active pixels being assigned with a pixel value greater than 100 in a given 3×3 kernel;
performing the enhancement from white-to-black transition in the horizontal direction when the determined sum of active pixels being assigned with a pixel value greater than 100 is more than 4 active pixels in the given 3×3 kernel; or
performing the enhancement from black-to-white transition in the horizontal direction when the determined sum of active pixels being assigned with a pixel value greater than 100 is more than 4 pixels in the given 3×3 kernel.

12. A digital printer for enhancing an object present in an input image, comprising:
a processor;
a digital front end (DFE) module, coupled to the processor, to:
receive a print job at the digital printer, wherein the print job comprising the input image;
convert the input image into a digital bitmap image comprised of an array of pixels, wherein each pixel being assigned with a pixel value representing printing information;
based on the pixel value, detect edge pixels of the object present in the input image; and
perform enhancement on the edge pixels of the object present in the input image, wherein for each edge pixel, the enhancement is being performed by:
forming a window around the edge pixel with a height and a width of predefined pixels;
calculating sum of active pixels in columns and sum of active pixels in rows for the window;
based on the calculation, determining direction of edge of the object present in the window, and determining whether the edge pixel is formed due to black-to-white transition or white-to-black transition; and
based on the determination, performing the enhancement on the edge pixel in the window; and
a digital rear end (DRE) module, coupled to the processor, to generate an output image based on the enhancement performed on the edge pixels the object, and to print the output image at the digital printer.

13. The digital printer of claim 12 , wherein the DFE module receives the print job in a page description language (PDL) file from a user device.

14. The digital printer of claim 12 , wherein the DFE module comprises an image raster processor to:
decompose the print job using commands and data stored in the print job to extract the input image; and
perform raster image processing on the input image to convert the input image into the digital bitmap image.

15. The digital printer of claim 14 , wherein the image raster processor is to form the window around the edge pixel with a height and width of 9 pixels.

16. The digital printer of claim 14 , wherein the image raster processor is to split the window into nine 3×3 kernels.

17. The digital printer of claim 16 , wherein the image raster processor is to:
calculate the sum of active pixels in columns of the window;
determine whether the sum of active pixels in columns is greater than a predefined threshold; and
perform enhancement in vertical direction when the sum of active pixels in columns is greater than the predefined threshold.

18. The digital printer of claim 17 , wherein the predefined threshold is 7.

19. The digital printer of claim 17 , wherein the enhancement is performed by:
determining a sum of active pixels being assigned a pixel value of greater than 100 in a given 3×3 kernel;
performing the enhancement from white-to-black transition in the vertical direction when the determined sum of active pixels being assigned a pixel value of greater than 100 is more than 4 active pixels in the given 3×3 kernel; or
performing the enhancement from black-to-white transition in the vertical direction when the determined sum of active pixels being assigned a pixel value of greater than 100 is more than 4 active pixels in the given 3×3 kernel.

20. The digital printer of claim 16 , wherein the image raster processor is to:
calculate the sum of active pixels in rows of the window;
determine whether the sum of active pixels in rows is greater than a predefined threshold; and
perform enhancement in horizontal direction when the sum of active pixels in rows is greater than the predefined threshold.

21.

Assignees

• Xerox Corp

Inventors

• Subbaian Sudhagar
• Gopalakrishnan Sainarayanan
• Palanivel Dhevendra Alagan

Classifications

• H04N2201/0094

  Multifunctional device, i.e. a device capable of all of reading, reproducing, copying, facsimile transception, file transception · CPC title

• H04N1/4092 Primary

  Edge or detail enhancement · CPC title