Image analysis – Image enhancement or restoration
Reexamination Certificate
1998-04-14
2001-03-27
Rogers, Scott (Department: 2624)
Image analysis
Image enhancement or restoration
C382S261000, C382S263000, C382S264000, C382S266000, C382S274000, C382S172000, C382S192000, C382S199000
Reexamination Certificate
active
06208763
ABSTRACT:
TECHNICAL FIELD
This invention relates to discrete picture element or pixel imaging techniques, and, more particularly, to a technique for analyzing and modifying signals or values representative of pixels in such images to provide a more readily understandable overall image in a computationally efficient manner. The technique is particularly suitable for medical imaging systems and modalities, such as magnetic resonance imaging.
BACKGROUND ART
A variety of discrete pixel imaging techniques are known and are presently in use. In general, such techniques rely on the collection or acquisition of data representative of each discrete pixel composing an image matrix. Several modalities are available for producing the data represented by the pixels, including magnetic resonance techniques, X-ray techniques, and so forth. Depending upon the particular modality employed, the pixel data is detected and encoded, such as in the form of digital values. The values are linked to particular relative locations of the pixels in the scanned subject image. After data values representative of pixels making up the entire image matrix have been acquired, the image is reconstituted by processing the individual pixel values.
The utility of a processed image is often largely dependent upon the degree to which it can be interpreted by users. For example, in the field of medical diagnostics and treatment, MR, X-ray, and other images are most useful when they can be easily understood and compared by an attending physician or radiologist. Moreover, while a number of image processing parameters may control the final image presentation, it is often difficult to determine which of these parameters, or in what combination the parameters may be adjusted to provide the optimal image presentation. Often, the image processing techniques must be adjusted in accordance with empirical feedback from the physician.
The facility with which a reconstituted discrete pixel image may be interpreted by an observer may rely upon intuitive factors of which the observer may not be consciously aware. For example, a physician or radiologist may seek specific structures or specific features in an image. In medical imaging, such features might include bone, soft tissue or fluids. Such structures may be physically defined in the image by contiguous edges, contrast, texture, and so forth. The presentation of such features often depends heavily upon the particular image processing technique employed for converting the detected values representative of each pixel to modified values used in the final image. The signal processing technique employed, thus, can greatly affect the ability of the observer to visualize salient features of interest. The technique should therefore carefully maintain structures, as well as abnormal or unusual structures, while providing adequate textural and contrast information for interpretation of these structures and surrounding background.
Known signal processing systems for enhancing discrete pixel images suffer from certain drawbacks. For example, such systems may not consistently provide comparable image presentations in which salient features or structures may be easily visualized. Differences in the reconstituted images may result from particularities of individual scanners and circuitry, as well as from variations in the detected parameters (e.g. molecular excitation or received radiation). Differences can also result from the size, composition and position of a subject being scanned. Signal processing techniques employed in known systems are often difficult to reconfigure or adjust, owing to the relative inflexibility of hardware or firmware devices in which they are implemented. Finally, known signal processing techniques often employ computational algorithms which are not particularly efficient, resulting in delays in formulation of the reconstituted image or under-utilization of signal processing capabilities.
DISCLOSURE OF THE INVENTION
The invention provides an improved technique for enhancing discrete pixel images in a computationally efficient manner. The technique provides for identification of salient structures within the image, and for identification of pixels representative of such structures. In an exemplary embodiment, following identification of the structures, portions of the image, including structural and non-structural regions are smoothed. Structural regions may be smoothed to enhance structural features in dominant orientations. Non-structural regions may be homogenized to provide an understandable background for the salient structures. The structures may be further sharpened, and minute regions may be identified which are considered representative of noise. Such artifacts may be smoothed or removed from the defined structure, depending upon their size and position. Original texture may be added back to non-structural regions to further facilitate interpretation of both the non-structural and structural features. The technique is particularly useful in magnetic resonance imaging systems, but may be employed over a wide range of modalities.
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Fletcher Yoder & Van Someren
General Electric Company
Rogers Scott
LandOfFree
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