Unsharp masking for image enhancement
AssigneesHitachi, Ltd., Hitachi Medical Corporation
InventorsKoichi Morishita, Shimbu Yamagata, Tetsuo Okabe, Tetsuo Yokoyama, Kazuhiko Hamatani
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Abstract
In an unsharp masking processing for sharpening images such as radiographic images, an emphasizing coefficient of an image and parameters for real-time change of picture quality are set interactively. The entire image is divided into a plurality of regional images and filtering optimized for each pixel image is effected using a standard deviation computed for each regional image and a density difference between pixel images.
Claims8
A method of radiographic image enhancement for an unsharp masking processing, comprising the steps of dividing an image into a plurality of local images;
- obtaining an unsharp image by averaging neighboring pixel values at local regions of the original image;
- subtracting the unsharp image from the original image to produce a sharp image;
- and adding an original image at a desired ratio to the sharp image to create a processed image,
- wherein said averaging step comprises effecting a weighted mean arithmetic operation of the pixel values of the local regions based on a weight coefficient which is determined in accordance with a monotonically decreasing or increasing function with respect to a density difference between a central pixel value and neighboring pixel values.
Dependencies are inferred from the claim text.