Abstract: A method for processing an image for the removal of spot defects comprising scanning and sampling the image to generate any array of pixel image values and constructing a corresponding array of pixel image values for the processed image by carrying out the following steps: (a) examining the image values of each pixel of a predetermined subset of pixels in a block surrounding a central pixel thereby determining the image value corresponding to the highest and lowest values in said predetermined subset of said block (A.sub.high and A.sub.low respectively), (b) determining the image value corresponding to the central pixel of said block (A.sub.center), (c) calculating either the ratio: R.sub.1 =(A.sub.low -A.sub.center)/(A.sub.high -A.sub.low) or the ratio R.sub.2 =(A.sub.center -A.sub.high)/(A.sub.high -A.sub.

Abstract: A method of processing an image for noise reduction, comprising the steps of: (a) generating from the image an array of pixel image values representative of the light values of its pixels; (b) grouping the pixel image values into groups corresponding to groups of pixels aligned along a predetermined direction; (c) processing a group of pixel image values using a transform algorithm and a thresholding operation to separate image components from noise components; (d) repeating step (c) with each group of pixel image values corresponding to groups of pixels aligned along the predetermined direction, the position of which group is translated by a fixed number of pixels with respect to the preceding group; (e) accumulating and averaging the image value components from every group contributing to each image element so as to provide an array of processed pixel image values having a partially reduced noise component; (f) repeating steps (b) to (e) with groups of pixel images values having noise components partially r

Abstract: An electronic image processing system, providing image enhancement and noise suppression, processes signals representing an array of picture elements, or pels. The system is of the kind providing a feature-enhanced output by the addition of outputs of a high-pass filter acting as an image-feature detector and a complementary low-pass filter. The low-pass filter, which also acts as an image-feature detector, includes a bandpass filter and a further low-pass filter. The latter filter (122) includes a prefilter (130 and FIG. 22) and a sub-sampling filter (132) based on a set of weighting patterns in the form of sparse matrices (FIG. 23). The bandpass filter (120) includes a similar prefilter (128) and a sub-sampling filter (134) based on a set of weighting patterns in the form of sparse matrices (FIGS. 26 and 27) that act as detectors of selected image features.

Abstract: An electronic image processing system, for image enhancement and noise suppression, from signals representing an array of picture elements, or pels. The system is of the kind providing a feature-enhanced output by the addition of outputs of a high-pass filter acting as image-feature detector and a complementary low-pass filter. The low-pass filter also acts as an image-feature detector and includes a prefilter (130 and FIG. 22) and a sub-sampling filter (32) based on a set of weighting patterns in the form of sparse matrices (FIG. 23). The sub-sampling filter in a bandpass channel of the low-pass filter (206 and FIG. 28) comprises a pair of gradient detectors (210, 220, 230, 240 and FIGS. 32, 33, 34, 35) arranged back to back.

Abstract: An image processing method is provided for reducing noise in a sampled image, particularly for reducing noise in an image divided into blocks of sampled image elements that are transformed by a linear procedure, such as the Walsh-Hadamard transform, and improved regarding visible noise by non-linear thresholding of the transform coefficients. By operating the process in a hierarchy of stages, each stage employing a block operating on image signals derived from a preceding stage, and by overlapping the blocks processed in each stage, the processed signal from each image element is the linear combination of many transform coefficients from each stage and from each overlapped block within each stage. Such a large number of contributions making up each processed image element assures that the processed image is generated without a characteristic block-like structure due to block transform processing while the wanted components of the image are rendered with minimal image loss or distortion.

Abstract: An electronic image processing system, using image dissection by solid state devices or by scanning and sampling, applies a signal representing a succession of signal values on an array of picture elements to complementary high and low pass electronic filters to produce an output signal in which a desired image feature is enhanced and noise is suppressed. The high pass filter, e.g. FIG. 1, comprises at least one matched pair of signal weighting gradient detectors, e.g. FIGS. 3 and 5, arranged back-to-back to detect a brightness transition 10, as shown in FIGS. 4 and 6, and having their outputs cored independently. Each pair will be sensitive to gradients in a particular direction in the array, e.g. horizontal, vertical or diagonal. The system is applicable to two-dimensional spatial arrays, three dimensional spatial arrays, and also to the temporal dimension, e.g. succession of moving pictures.