Showing papers on "Bilateral filter published in 1993"

Method and apparatus for variable block size interpolative coding of images

Abstract: The method and apparatus of the .present invention presents an apparatus and-method for block adaptive image compression. The method and apparatus of the present invention reduces data storage and transmission requirements by sending a subset of the entire pixel data set existing in an image pixel data set. The pixels that are stored are referred to as primary pixels. The remaining pixels that are not transmitted or stored are referred to as secondary pixels. These secondary pixels are estimated from the primary pixels. A high fidelity image can be reproduced utilizing only the primary pixels. The method and apparatus of the present inventions estimates the secondary pixel values from the primary pixel values by predicting that a secondary pixel will look like the surrounding primary pixels, or by interpolating a value for the secondary pixels by summing the surrounding primary pixels and averaging them to obtain a value for the secondary pixel.

Flame detection method and apparatus

Abstract: A flame detection apparatus and method includes a camera, preferably operating in the near I.R. which produces a succession of images of a space to be monitored. The image intensity of each pixel in each image is converted to a binary value by comparing it with the average intensity value for that image. For each pixel in an image the average intensity value for all of the images is calculated. The binary intensity value of each pixel in an image is then compared with the binary intensity value of the corresponding pixels in all the other images to produce a crossing frequency value dependent on the number of times those binary values change state. The average intensity values and the crossing frequency values are then processed for each pixel according to a predetermined relationship to produce a constant. If the values of this constant for a cluster of adjacent pixels are found to be the same or nearly so, this is considered to indicate a flame. The crossing frequency values may be processed to eliminate those values lying outside a frequency range corresponding to flames so as to eliminate the corresponding pixels from the final assessment step.

Image processing unit processing pixel data according to scan line density

Abstract: An image processing unit comprises an image scanning unit for scanning an original at a plurality of predetermined line densities, a smoothing unit for smoothing the intensity of each pixel, the intensity of each pixel being corrected to be the average intensity of a predetermined number of pixels surrounding each pixel in a predetermined pixel area, a binarizing unit for binarizing the corrected pixel by a half-tone processing, and a pixel area changing unit for changing the pixel area based on the line density employed by the image scanning unit. The intensity of each pixel may be corrected, by using pixels included in the predetermined pixel area, based on the existence of a pixel corresponding to a contour or a fine line in the original in the pixel area. A clear image of a mesh picture is obtained without generation of moire, blurring of contours, or breaking of fine lines.

A method for detecting and removing errors exceeding a specific contrast in digital video signals

Abstract: A method for detecting and removing errors in pictures associated with a picture sequence in digital video signals is disclosed. For this purpose an error detector and a filter for continuous processing of pixels associated with said pictures is used. The error detector detects an error if at least one error pixel, being a pixel with a specific contrast, i.e. difference in pixel intensities, is found when comparing the pixel intensities of pixels belonging to at least two pictures in said picture sequence. The error detector determines an error shape, and the filter which is an adaptive filter, replaces the intensity of a current error pixel with a mathematical function of pixel intensities of the current pixel and pixels surrounding the error shape.

Z buffer initialize and update method for pixel block

Abstract: A method is provided for initializing and updating a group of pixels contained on a display in blocks. A group of pixels is considered as a block and has a status word associated therewith. This status word maintains a running total of the maximum z value of any pixel contained within a group, or block of pixels. In this manner, once a block of pixels is rendered on to the display screen a comparison can be made between the current pixels being displayed and a group of pixels which are to be displayed. The minimum z value of the group of pixels to be displayed is compared with the maximum z value for the group of pixels currently being displayed. If the current maximum z value, as stored in the status word, is less than the minimum z value for the pixels to be displayed, then the group of pixels currently being displayed will all "win" when compared to the pixels in the group to be displayed. Thus, a full block bypass of the group of pixels to be displayed is implemented, thereby saving considerable time and overhead when compared to conventional z buffer systems that compare z values for each individual pixel.

Spatial filter of an image signal processor providing alternating line images without moire

Abstract: An error distribution type image signal processor has a spatial filter which has a positive filter coefficient assigned to pixels adjoining a pixel of interest in main and sub scan directions and a negative filter coefficient assigned to pixels adjoining the pixel of interest in diagonal directions. The sum of a filter coefficient for the pixel of interest and the filter coefficients for the pixels adjoining it is unity. Therefore, high frequency image signals of the pixels adjoining the pixel of interest in the diagonal directions are attenuated, and high frequency image signals of the pixels adjoining the pixel of interest in the main and sub scan directions are amplified. Accordingly, amplitudes of the pixels adjoining the pixel of interest in the diagonal directions are minimal, so that an image of the pixel of interest is clarified and emphasized.

Three dimensional median and recursive filtering for video image enhancement

Abstract: According to a presently preferred embodiment of the invention, image enhancement apparatus for digital video images comprises a two-stage filter (12) comprising a median filter (12) and recursive filter (14). The median filter operates in one, two, and three dimensions wherein the cluster of pixels framing the center pixel are ranked, and the median value of the pixel cluster is chosen as the correct pixel value. The pixel cluster configuration is selectable, as are the planes where the pixels are located. Multiple weights may be given to the appropriate median filter inputs. A motion detector (78) is used to prevent replacement of each pixel by its pixel cluster median value when there is excessive motion. Finally an adjustable pixel-replacement threshold is defined. Each pixel must deviate from its median value before it is replaced by that value. In the presence of rapid motion in the picture, the operation of the medial filter is reduced or halted by a properly derived motion signal according to the present invention, thus preventing motion artifacts from occurring.

A multi-dimensional non-linear edge-preserving filter for magnetic resonance image restoration

Abstract: The authors present a multi-dimensional non-linear edge-preserving filter for restoration and enhancement of magnetic resonance images (MRI) The filter uses both of the inter-frame (parametric or temporal) and intra-frame (spatial) information to filter the additive noise from an MRI scene sequence It combines the approximate maximum likelihood (equivalently, least squares) estimate of the inter-frame pixels, using MRI signal models, with a trimmed spatial smoothing algorithm, using a Euclidean distance discriminator to preserve partial volume and edge information The filter's structure is parallel, making its implementation on a parallel processing computer trivial Details of the filter implementation for a sequence of four multiple spin-echo images is explained, and the effects of filter parameters (neighborhood size and threshold value) on the computation time and performance of the filter is discussed The filter is applied to MRI simulation and brain studies, serving as a pre-processing procedure for the eigenimage filter It outperforms conventional pre- and post-processing filters, including spatial smoothing, low-pass filtering with a Gaussian kernel, median filtering, and combined vector median with average filtering >

System and method for converting halftone images to continuous-tone images

Abstract: An image processing system converts unscreened and other halftone images to continuous tone images. Value data is sequencitally generated for successive pixels of a screened orunscreened halftone image. Each image pixel is Sigma filtered with a predetermined set of filter parameters including the filter window size and a Sigma difference range that is applied to determine which pixels in the filter window are counted in determining average window pixel values. An output continuous tone image containing the Sigma filtered pixels is generated for storage and/or processing to a halftone copy or print.

Color filter for solid-state image pickup element and signal processor for solid-state image pickup element

Abstract: PURPOSE: To extend the dynamic range by reducing a transmission rate of a color filter having a maximum transmission rate so that an output signal is nearly equal to that of other color filters. CONSTITUTION: Let an output signal component depending on a spectral characteristic in a range from 400nm to 500nm when a reference white level is picked up to be (b), an output signal component depending on a spectral characteristic in a range from 500nm to 600nm to be (2g) with respect to pixels of a Cy filter, and let an output signal component depending on a spectral characteristic in a range from 600nm to 700nm to be (r) with respect to pixels of a Ye filter. Then an output signal Go of picture elements of a G filter is 2g, an output signal Cyo of pixels of a Cy filter is b+2g, and an output signal Yeo of pixels of a Ye filter is 2g+r. Furthermore, the spectral characteristic of a W filter is formed so that an output signal Wo of pixels of the Y filter is 3(b+2g+r)/4. That is, the spectral characteristic of the color filter of a conventional solid- state image pickup element is multiplied by 3/4. COPYRIGHT: (C)1995,JPO

Method of forming a composite image starting from two different images.

Abstract: Method of forming a composite image from two different images. It is of the type consisting in using each original image broken down into pixels, each pixel being allocated a code with which a colour is associated, the primary components of which are determined by a palette of colours which is able to generate the said primary components in order to recompose the said pixel on a medium, and it is characterised in that the composite image is generated by juxtaposing, on the medium, pixels or groups of pixels of the different original images distributed in such a way that a pixel or group of pixels occupies, on the composite image, the same spatial position as they occupied on the original images. Applications especially to producing a composite image from two images of maps of geophysical parameters.