Non-linear adaptive image filter for filtering noise such as...

Details Non-linear adaptive image filter for filtering noise such as... Non-linear adaptive image filter for filtering noise such as...

2001-05-17

2003-07-29

Rogers, Scott (Department: 2624)

Image analysis

Image enhancement or restoration

Edge or contour enhancement

C382S199000, C382S206000, C382S205000, C375S240290

Reexamination Certificate

active

06600839

ABSTRACT:

TECHNICAL FIELD
The present invention is related generally to digital signal processing and, in particular, digital signal processing of images.
BACKGROUND OF THE INVENTION
Many modern-day image processors utilize compression (or coding) techniques to minimize the amount of memory needed to store and process the images. The compression techniques used are those typically established by the International Standards Organization. For example, a Joint Photographic Experts Group (JPEG) of the International Standards Organization developed a JPEG digital data compression technique for editing still images, as well as for use in color facsimile (FAX) machines, and medical imaging systems. Digital image recorders use a compression technique developed by a Moving Pictures Expert Group (MPEG) to minimize the amount of data stored when acquiring or processing moving (or motion) pictures. An MPEG-1 standard generally is used for relatively low-level resolution, low-bit rate image sequences. An MPEG-2 standard has been developed to accommodate relatively high resolution, high-bit rate image sequences of the type generally used for full screen playback, such as in entertainment systems, web browsers, television (TV), high-definition TV (HDTV), or with image games played on personal computers (PCs).
These compression techniques typically divide an image into blocks of pixels (block coding) for processing. During processing, a well known discrete cosine transform (DCT) is applied to each block of pixels, the results of which are quantized and encoded. When the image is to be displayed, on a TV or PC, for example, it must be decoded in advance. Depending on the selected bit rate (i.e., compression factor), the images present noticeable degradation due to quantization errors. For example, when the compression ratio is increased, the artifacts of block coding the image become visible around the block boundaries. These blocking artifacts primarily consist of two types of artifacts: grid noise and staircase noise. When processing the image, the noise has characteristics similar to those of an image's fine details, such as the image's edges and textures. Any filtering of the noise thus usually filters the image's edges and textures, as well, causing blurring. It can be appreciated therefore that what is needed is a technique to reduce the blocking artifacts without blurring the image's fine details.
SUMMARY OF THE INVENTION
Presented herein is a system and method to reduce blocking artifacts that overcome the limitations associated with image compression standards. An example embodiment stores several rows of an image to be processed in line memories. The image rows contain a target pixel as well as pixels neighboring the target pixel. This exemplar extracts global metrics from the image, estimates local metrics related to the target pixel and the neighboring pixels as local metrics, uses fuzzy logic to determine the number of pixels to be processed, determines the difference in gray level values between the target pixel and the neighboring pixels, and smoothes any abrupt transitions in gray levels from the target pixel to neighboring pixels using a dual ramp generator.
Further features and advantages as well as the structure and operation of various embodiments are described in detail below.


REFERENCES:
patent: 6285801 (2001-09-01), Mancuso et al.
patent: 0797349 (1997-09-01), None
patent: 0881837 (1998-12-01), None
Hsu, Yuh-Feng and Yung-Chang Chen, “A New Adaptive Separable Median Filter for Removing Blocking Effects,”IEEE Trans. on Consumer Electron., 39(3):510-513, Aug. 1993.
Jarske et al., “Post Filtering Methods for Reducing Blocking Effects from Coded Images,”IEEE Trans. on Consumer Electro., 40(3):521-526, Aug. 1994.
Ramamurthi, Bhaskar and Allen Gersho, “Nonlinear Space-Variant Postprocessing of Block Coded Images,”IEEE Trans. Acous., Speech, and Signal Proc., ASSP-34(5):1258-1268, Oct. 1986.
Reeve III, Howard C. and Jae S. Lim, “Reduction of Blocking Effects in Image Coding,”Opt. Eng., 23(1):034-037, Jan.-Feb. 1984.
Reid et al., “Second-Generation Image Coding: An Overview,”in ACM Computing Surveys, 29(1):3-29, Mar. 1997.
Xiaobing Lee et al., “Information Loss Recovery for Block-Based Image Coding Techniques—A Fuzzy Logic Approach,”IEEE Transactions on Image Processing4(3):259-273, Mar., 1995.

Affiliated with

Also associated with

Rating

Non-linear adaptive image filter for filtering noise such as... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Non-linear adaptive image filter for filtering noise such as..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-linear adaptive image filter for filtering noise such as... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3099648