An input image is inputted into a pre-process circuit and a spatial filter. The pre-process circuit emphasizes a linear shadow or an edge to some extent, or reduces noises overall. Following pre-processing, the image signal is supplied to a direction detection circuit, a direction and its intensity of an area of interest are detected. These two results of the detections are correlated with peripheral areas of interest to some extent by a vector filter. An output of the vector filter is supplied to a spatial filter coefficient generation circuit, and a filter coefficient of the spatial filter is decided. The spatial filter processes the input image based on the direction of the shadow and its intensity, whereby selectively suppressing noise components of the background in real time without damaging the contrasts of a linear shadow or an edge-like shadow.
Signal-adaptive noise reduction in digital radiographic images is described herein. Embodiments comprise methods for signal-adaptive noise reduction in digital radiographic images, comprising the steps of: obtaining raw x-ray image data of an imaged object; processing the raw x-ray image data to create processed x-ray image data; inputting at least one of the raw x-ray image data and the processed x-ray image data to an image processor; developing at least one of a first intensity modulation image from the raw x-ray image data and a second intensity modulation image from the processed x-ray image data; deriving a structure-dependent noise filtered image using the processed x-ray image data; performing signal attenuation-dependent blending; and creating a noise-reduced digital x-ray image therefrom. Computer-readable mediums encoded with programming for facilitating signal-adaptive noise reduction in digital radiographic images, and digital radiographic imaging systems comprising such programming, are also described.
Method and apparatus for correlating data records acquired in a signal acquisition device includes the steps of extracting an area of interest from the data record displayed on said signal acquisition device, normalizing the area of interest, creating a filter based upon normalized values of the area of interest and passing the data record through said filter to obtain a correlation curve. Normalization of the area of interest includes obtaining a plurality of points defining the area of interest, calculating the mean of the said plurality of points and subtracting said mean from each of the said plurality of points. Creating the filter includes using the normalized values of the area of interest as coefficients for the filter.
Spatial noise is reduced in an image having a plurality of pixels by detecting object boundaries and unstructured areas in the image and applying 3-tap high pass filters to each pixel in the image in at least four, but less than eight directions to determine the best direction for local low pass filtering. Low pass filtering is applied only along object boundaries and unstructured areas within the image so as to minimize the tendency to blur image edges. Using only four high pass filters to locate horizontal, vertical and diagonal image edges passing through the center of a 3.times.3 pixel array provides good results.
