Parameterized sharpening and smoothing method and apparatus

• US 20030026495A1
• Filed: 05/01/2002
• Published: 02/06/2003
• Est. Priority Date: 03/07/2001
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Gillihan, Amanda Jean, Atkins, C. Brian, Gondek, Jay Stephen
• Application Number:
  US10/136,958
• Publication Number:
  US 20030026495A1
• Time in Patent Office: Days
• US Class Current: 382/261
• CPC Class Codes: G06T 2200/24 involving graphical user interfaces [GUIs]
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement

Abstract

Provided is a method and apparatus of processing an image using filters. The method and apparatus receives an input pixel and a pixel window associated with the input pixel from the image, classifies the input pixel using the pixel window into a range of classes identifying pixels suitable for various degrees of smoothing and sharpening operations, receives parameter independently set for sharpening and smoothing the image, and selects a filter for processing the input pixel based upon the pixel classification and the parameter settings for sharpness and smoothness.

Claims

1. A method of processing an image with filters, comprising:

receiving an input pixel and a pixel window associated with the input pixel from the image;

classifying the input pixel using the pixel window into classes identifying pixels suitable for various amounts of smoothing and sharpening operations;

receiving parameter settings for sharpening and smoothing the image, wherein the sharpening and smoothing parameters can be set independently; and

selecting a filter for processing the input pixel based upon the classification and the parameter settings.

2. The method of claim 1 wherein the input pixel is classified for smoothing when a variation of the input pixel compared with the pixel window does not exceed a predetermined threshold of variation.

3. The method of claim 2 wherein the variation is determined according to a mean average deviation of the input pixel computed using the pixel window.

4. The method of claim 1 wherein the input pixel is classified for sharpening when a variation of the input pixel exceeds a predetermined threshold of variation and edges are detected within the pixel window.

5. The method of claim 4 wherein the edges are detected using one or more gradients.

6. The method of claim 1 wherein the parameter settings for smoothing and sharpening an image can be independently set through a user-interface in an application.

7. The method of claim 1 wherein the parameter settings for smoothing and sharpening an image can be independently set through a user-interface in a device driver.

8. The method of claim 1, wherein the filter is selected from a set of filters including at least one smoothing filter, at least one sharpening filter and at least one a passthrough filter.

9. The method of claim 3, wherein the mean absolute deviation is calculated using the sum of the differences between an input pixel value and a pixel window average.

10. An apparatus for processing an image, comprising:

a pixel storage area that receives an input pixel and a pixel window associated with the input pixel from the image;

a pixel classification module that classifies the input pixel using the pixel window into classes identifying pixels suitable for various amounts of smoothing and sharpening operations;

a storage area that receives parameter settings for sharpening and a smoothing to control the degree of sharpening and smoothing image enhancement, wherein the degree sharpening and smoothing parameters can be set independently by parameters; and

a selection module that selects a filter for processing the pixel based upon the pixel classification and the parameter settings for sharpness and smoothness.

11. The apparatus of claim 10 wherein the pixel classification module classifies the pixel for smoothing when the variation level of the input pixel compared with the pixel window does not exceed a predetermined threshold of variation.

12. The apparatus of claim 11 wherein the variation is determined according to a mean absolute deviation (MAD) of the input pixel computed using the pixel window.

13. The apparatus of claim 10 wherein the input pixel is classified for sharpening when the pixel variation exceeds a predetermined threshold of variation within the pixel window and edges are detected within the pixel window.

14. The apparatus of claim 13 wherein the edges are detected using one or more gradients against the pixel array.

15. The apparatus of claim 14 wherein the edges are further detected using one or more linear gradients.

16. The apparatus of claim 10 wherein the parameter settings for smoothing and sharpening an image can be independently set through a user-interface in an application.

17. The apparatus of claim 10 wherein the parameter settings for smoothing and sharpening an image can be independently set through a user-interface in a device driver.

18. A means for processing an image, comprising:

a means for receiving an input pixel and a pixel window associated with the input pixel from the image;

a means for classifying the input pixel using the pixel window into a range of classes identifying pixels suitable for various degrees of smoothing and sharpening operations;

a means for storing the parameters that correspond to a sharpen parameter and a smooth parameter setting to control the degree of sharpening and smoothing in the image enhancement, wherein the sharpening and smoothing parameters can be set independently; and

a means for selecting a filter for processing the input pixel based upon the pixel classification and the parameter settings for sharpness and smoothness.

19. A computer program product, tangibly stored on a computer-readable medium, comprising instructions operable to cause a programmable processor to:

receive an input pixel and a pixel window associated with the input pixel from an image;

classify the input pixel using the pixel array into a range of classes identifying pixels suitable for various degrees of smoothing and sharpening operations;

store the parameters that correspond to a sharpen parameter and a smooth parameter setting to control the degree of sharpening and smoothing in the image enhancement, wherein the sharpening and smoothing parameters can be set independently; and

select a filter for processing the input pixel based upon the pixel classification and the parameter settings for sharpness and smoothness.

20. A system for processing images, comprising:

a processor that executes instructions for generating an image;

an image processing device that receives an input pixel and a pixel window associated with the input pixel from the image, classifies the input pixel using the pixel window into classes identifying pixels suitable for various degrees of smoothing and sharpening operations, stores the parameters that correspond to a sharpen parameter and a smooth parameter setting to control the degree of sharpening and smoothing in the image enhancement, wherein the sharpening and smoothing parameters can be set independently and selects a filter for processing the input pixel based upon the pixel classification and the parameter settings for sharpness and smoothness; and

an image generation device that receives one or more processed pixels in the image and processes them for visual presentation.

21. The system of claim 20 further comprising,

a storage device that stores routines containing instructions for execution on the processor.

22. The system of claim 21 wherein the visual presentation is done using a display device.

23. The system of claim 21 wherein the visual presentation is done using a printer device.

24. A method of creating an image processing system, comprising:

providing a user-interface facilitating the setting of parameters to determine the degree of sharpening and smoothing of an image;

receiving a set of filters that perform sharpening and smoothing image enhancement

classifying pixels types based on pixel characteristics; and

arranging the set of filters according to both the pixel characteristic classifications and each of the independent settings for sharpening and smoothing.

25. The method of claims 24 wherein the user-interface for setting the parameters is accessible through an application.

26. The method of claim 24 wherein the user-interface for setting the parameters is accessible through a device-driver.

27. The method of claim 24 wherein the user-interface allows the parameters for sharpening and smoothing to be set independently.

28. The method of claim 27 wherein the user-interface allows each parameter to be set to at least a low, medium or high setting.

29. The method of claim 24 wherein the set of filters includes precomputed linear filters constructed from numerical coefficient values multiplied by corresponding pixel values in a pixel array wherein the resulting products are summed together.

30. The method of claim 24 wherein the set of filters includes adaptive filters whose coefficient values change depending on the input data.

31. The method of claim 24 wherein the pixel characteristics used to classify the pixels comprises noise, high-frequency detail and edges having vertical, horizontal and diagonal qualities.

32. The method of claim 24 wherein the filters for sharpening are arranged to enhance pixels classified as having edges.

33. The method of claim 24 wherein the filters for smoothing are arranged to enhance pixels classified as having noise.

34. The method of claim 24 wherein the no filters are applied to pixels classified as having high-frequency detail.