System and method for identifying and classifying color regions from a digital image

• US 8,515,163 B2
• Filed: 07/09/2012
• Issued: 08/20/2013
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: Tungsten Automation Corp.
• Original Assignee: Kofax Incorporated
• Inventors: Cho, Seungyeon, Bither, William
• Primary Examiner(s): Seth, Manav
• Application Number:
  US13/544,830
• Publication Number:
  US 20120275695A1
• Time in Patent Office: 407 Days
• Field of Search: 382100-101, 382104-105, 382112-113, 382162-231
• US Class Current: 382/162
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/18105 related to colour
• CPC Class Codes: G06V 30/413 Classification of content, e.g. text, photographs or tables

Abstract

A system and method of identifying and classifying regions of a digital image. The method includes an initial step of inputting an image as a color digital image. Subsequently, information that identifies color regions of the color digital image is obtained. Finally, color and non-color regions of the color digital image are classified based upon the identifying information.

Claims

1. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information; and

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions, wherein said photo regions are classified by the following steps;

transforming said color digital image to gray scale;

applying a first median filtering method to said gray scale image creating a first filtered image;

applying a second median filtering method to said gray scale image creating a second filtered image;

creating a difference image from between said first and second filtered images;

converting said difference image to a binary image;

obtaining a set of bounding boxes of black pixels in said binary image through a connected components method; and

applying a size analysis to said connected components wherein connected components having a size below a predetermined threshold are marked as non-photo regions and remaining bounding boxes of said connected components are photo regions.

2. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

assessing a bit-depth of said color digital image to determine whether said image is entirely black and white or entirely grayscale; and

terminating said classification of said regions if said image has a bit-depth indicating that it is black and white or grayscale.

3. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

resampling and resizing said image to expedite the identification and classification of said regions of said digital image.

4. The system of claim 3 wherein the program further includes instructions for restoring said image to its original size prior to said resampling.

5. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

identifying black border regions in said image;

removing any identified black border regions.

6. The system of claim 5 wherein said identification of black border elements includes the steps of:

determining whether pixels that comprise said color digital image are black;

scanning said black pixels along a dimension of said image to determine a boundary of said black border;

establishing said boundary of said black border where said non-black pixels exceed one-percent of a total of said pixels of said scanned dimension.

7. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions; and

identifying gray elements in said image;

removing any identified gray elements.

8. The system of claim 7 wherein identifying gray elements includes:

transforming said color digital image to gray scale to create a gray scale image;

computing a Malahanobis distance for each color pixel in said color digital image to a corresponding pixel of said transformed gray scale image; and

marking a pixel in said color digital image as gray if it exceeds a predetermined distance from its counterpart in said gray scale image.

9. The system of claim 7 wherein said identification of color elements includes the following:

creating a binary image from said color digital image;

marking any pixels previously identified as gray or photo elements as white and any remaining pixels as black;

applying a connected components method to obtain bounding boxes of connected components of said black pixels;

merging any overlapping bounding boxes into a single bounding box;

applying a size analysis method to said bounding boxes in which connected components having a bounding box of a smaller size than a predetermined value are marked as non-color and a remaining set of bounding boxes of said connected components are marked as a color region.

10. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

identifying background elements;

removing said background elements.

11. The system of claim 10 wherein identifying background elements includes:

creating a memory space having a width and height corresponding to that of said color digital image;

applying an HSL color transformation to said color digital image;

copying an H component from said HSL transformation for each pixel of said color digital image into said memory space;

applying an unsupervised clustering method to said H component data to identify background colors if present;

applying an image slicing method to said H component data to obtain a binary image in which background pixels are black;

obtaining a set of bounding boxes of using a connected components methodology for said black pixels; and

applying a size analysis to determine which bounding boxes are to be merged and considered background.

12. A system, comprising:

a processor; and

a program of instructions executable by the processor to perform a method of identifying and classifying regions of a digital image, said method comprising;

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

merging said photo and said color regions.

13. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information; and

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions, wherein said photo regions are classified by the following steps;

transforming said color digital image to gray scale;

applying a first median filtering method to said gray scale image creating a first filtered image;

applying a second median filtering method to said gray scale image creating a second filtered image;

creating a difference image from between said first and second filtered images;

converting said difference image to a binary image;

obtaining a set of bounding boxes of black pixels in said binary image through a connected components method; and

applying a size analysis to said connected components wherein connected components having a size below a predetermined threshold are marked as non-photo regions and remaining bounding boxes of said connected components are photo regions.

14. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

assessing a bit-depth of said color digital image to determine whether said image is entirely black and white or entirely grayscale; and

terminating said classification of said regions if said image has a bit-depth indicating that it is black and white or grayscale.

15. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

resampling and resizing said image to expedite the identification and classification of said regions of said digital image.

16. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

identifying black border regions in said image;

removing any identified black border regions.

17. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions; and

identifying gray elements in said image;

removing any identified gray elements.

18. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

identifying background elements;

removing said background elements.

19. Electronically-readable, non-transitory media embodying a program of instructions executable by a processor to perform a method of digital image analysis, the method comprising:

inputting an image as a color digital image;

obtaining information that identifies color and photo regions of said color digital image;

classifying color, photo, non-color and non-photo regions of said color digital image based upon said identifying information;

individually compressing said color, non-color, photo and non-photo regions based on a quality characteristic of each of said regions;

merging said photo and said color regions.