Image analysis – Image transformation or preprocessing – General purpose image processor
Reexamination Certificate
1999-01-20
2001-05-15
Au, Amelia M. (Department: 2623)
Image analysis
Image transformation or preprocessing
General purpose image processor
C382S205000
Reexamination Certificate
active
06233369
ABSTRACT:
BACKGROUND OF THE INVENTION
Morphology processing as it is applied to image processing and machine vision usually involves replacing each pixel in an image or image section being processed with a function of itself and its neighbor pixels.
The most useful functions are non-linear. Accordingly, a preferred technique that is well known in the art is to represent the function as a look-up table. The look-up table is indexed by a numerical value formed by concatenating all the pixel values found in a neighborhood together. For example, a morphology processing engine for 3×3 neighborhoods of binary pixel values needs to have an index value containing 9 bits, corresponding to a look-up table containing 512 different possible values. By setting the values in this look-up table, it is possible to choose an output value for each of the 512 possible input neighborhoods.
Iterative processing using different functions is an especially powerful technique. This sort of processing engine may be used to implement convex hull, various skeleton operators, operators that remove spatial noise, and many other operators which are useful for image processing and machine vision.
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Haralick, Robert M. and Shapiro, Linda G. “Computer and Robot Vision, Volume I”, Addison- Wesley, 1992.
Morphology processing is also applicable to gray-scale images, where each image pixel is represented by an intensity value. Most image processing and machine vision systems represent image intensity values using between 6 and 16-bit quantities. Implementing the morphology neighborhood functions using look-up tables is prohibitively expensive for these images, but several non-linear operators such as minimum and maximum may be implemented economically using appropriate processing hardware.
Used in conjunction with image arithmetic operations, morphology processing becomes even more useful. Image arithmetic may be used to implement a mask determining which pixels are to be processed. It may also be used to compare images with and without morphology processing, or images which have been subject to different processing steps.
One of the primary difficulties associated with morphology and other neighborhood-based processing is the fact that the processing function is only fully defined for pixels that have a complete complement of neighbors. Pixels that are adjacent to the boundary of the image have a number of neighbors which are outside of the image. The usual method of dealing with this problem is to produce a result image that is smaller than the original image. The original image must contain a quiet zone of background data surrounding the subject data to be processed.
SUMMARY OF THE INVENTION
The invention provides two specific improvements over existing apparatus and methods for performing morphology processing. First, the present invention provides a novel mechanism that permits a “mask” to be directly incorporated into the image.
Second, the present invention provides a means of automatically providing background data to the processing engine for pixels outside the original image so that the result image is always the same size as the original image.
These and other improvements are implemented in an improved processor for performing morphology computations on one or more adjacent pixels. The improved morphology processor includes a data flow controller, which provides pixel data in groups of adjacent pixels and provides framing signals. The morphology processor also includes a neighborhood generator, which receives the pixel data and framing signals from the data flow controller and which generates neighborhood data and corresponding neighborhood pixel-valid signals. Also included is one or more neighborhood processor, which receives the neighborhood data along with the corresponding pixel-valid signals and which automatically inserts background data for processing in place of invalid neighborhood pixels.
This invention incorporates a mask into a binary image by processing binary images or image data which are encoded using two bits rather than the usual one. The second bit is defined to be a “mask enable” data bit, which directs the processing machinery (processing “engine”) to pass the original data through to the output image regardless of the processing result for that pixel. This invention is particularly useful because the masked pixel data is permitted to participate in the computation of all of its neighboring pixels' results. This permits the use of “always 0” and “always 1” values in addition to the usual “0” and “1” values.
The invention also facilitates the morphology processing of both binary and gray-scale images by providing automatic background generation. For binary images, the background may be defined to have a value of “0” or “1”. This value is provided to the processing engine in place of all of the pixels which lie outside the original image. For gray-scale images, the minimum or maximum possible value is provided to the processing engine in place of all of the pixels which lie outside of the original image, effectively eliminating these values from consideration when the minimum or maximum of the neighborhood pixels is computed. The determination of whether a pixel is outside of the original image is implemented using the framing signals provided by the data flow controller along with the image data.
For example, when a “start of row” signal is asserted, the left-most pixel to be processed is known to be on the left boundary of the incoming image data. In this case, the neighborhood pixels to the left of this left-most pixel are outside the original image and the background value is provided to the processing engine for these neighborhood pixel values.
REFERENCES:
patent: 4395697 (1983-07-01), Dargel et al.
patent: 4791675 (1988-12-01), Deering et al.
patent: 4797806 (1989-01-01), Krich
patent: 5091972 (1992-02-01), Kwon et al.
patent: 5623624 (1997-04-01), Holland et al.
Acuity Imaging, LLC
Au Amelia M.
Bourque & Associates P.A.
Wu Jingge
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