Showing papers on "Channel (digital image) published in 1983"

Conversion of acoustic signals into visual signals

Abstract: For displaying spoken words as color pictures on a screen, each audio frequency, ie each acoustic sound, is assigned a respective color hue and each audio frequency spectrum a respective color mixture, by conducting acoustic signals through a three-channel triangular filter, each channel having a different central frequency, and controlling the intensity of a respective electron beam of a color television monitor as a function of a respective filter channel output

Data compression method for graphics images

Abstract: Graphic images are generally considered to be those images comprised of text and/or drawings. Data compression of graphics images is desired whenever a fast image transmission speed is desired in a limited band width channel. It is also used for storage of a large number of images in a limited capacity storage system. A high compression ratio is achieved by thresholding the graphics image to a bilevel black-white image at one bit per pixel and then employing a second data compression on the black-white image. At low resolution, bilevel images have poor quality at edges and a quality improvement is needed. The data compression apparatus and method disclosed separates the graphics image into at least first and second bit planes identifies edge pixels from the first bit plane indicating a black/white change, locates the edge pixels and generates at least a single bit for each edge pixel indicating whether the edge pixel has a maximum intensity value such as black or white or an intermediate gray intensity value. Intermediate values are not allowed except at edge pixels which enhances both quality and compressibility of the resulting graphics image.

Progressive scan television system employing vertical detail enhancement

Abstract: A flat-field television image having reduced visibility of horizontal scan lines is generated by receiving first and second fields of interlaced video and progressively generating a scanned image within a time for one incoming field. The progressive scanned image is formed from "real" and interpolated lines of luminance. In this arrangement the interpolated line is formed by weighting samples from time-successive lines. To improve the vertical detail of a progressively scanned image vertical detail information which may be obtained from the chrominance channel is combined with both "real" and interpolated lines, or one to the exclusion of the other, to enhance the image displayed.

Soft Decision Demodulation and Transform Coding of Images

Abstract: This paper describes a transform image coding system that uses soft decision demodulation to control channel errors. In soft decision demodulation, if certain received bits of a codeword representing a coefficient are unreliable, then the codeword is rejected and the corresponding coefficient is replaced with an estimate. By monitoring the three highest energy DCT coefficients, the reconstructed image quality can be improved for a channel with a bit error probability of 10-2.

Progressive scan television display system employing interpolation in the luminance channel

Abstract: A flat-field television image having reduced visibility of horizontal scan lines is generated by receiving first and second fields of interlaced video and progressively generating a scanned image within a time for one incoming field. The progressively scanned image includes interpolation and double-rate translation in the luminance channel and double-rate translation only in the chrominance channel. In one embodiment the two-times translation (each line repeated) is applied to the chrominance channel after separation from the luminance but prior to demodulation. In another embodiment the chrominance signal is two-times translated prior to demodulation thus requiring demodulation after double-rate translation.

Image processing method for graphics images

Abstract: Graphics images are generally considered to be those images comprised of text and/or line drawings. Data compression of graphics images is desired whenever a fast image transmission speed is desired in a limited band width channel. It is also used for storage of a large number of images in a limited capacity storage system. The method and apparatus described herein improves data compression, resolution and coding efficiency by eliminating transitions between gray levels at edges in an image, converting all gray levels to a common value to achieve a 3 level representation of a graphics image, and reversibly converting the 3 level representation to a bilevel double resolution representation by increasing the data sampling rate and therefore allowing the use of two level data compression techniques. A high resolution display or printed output may be obtained from the bilevel multiresolution representation.

Digital diagnostic imaging system

Abstract: THE INVENTION CONCERNING MEDICAL IMAGING. A MEDICAL IMAGING SYSTEM INCLUDES, IN PARTICULAR, A RADIOGRAPHIC DATA INPUT CHANNEL 12 AND A RADIOSCOPIC DATA INPUT CHANNEL 13 THAT ARE CONNECTED SELECTIVELY BY A SW1 SWITCH HAS AN IMAGE ENHANCEMENT SECTION 32 COMPRISING A VIDEO PROCESSING UNIT 24 AND A MEDICAL COMPUTER 26. USING A SAME IMAGE ENHANCEMENT SECTION FOR RADIOGRAPHIC DATA AND RADIOSCOPIC DATA PERMITS MAKE SAVABLE ECONOMY ON THE MATERIAL AND SOFTWARE NECESSARY FOR DIGITAL IMAGE ENHANCEMENT. APPLICATION TO RADIOLOGICAL FACILITIES.

Side-scan sonar mapping and computer-aided interpretation in the Santa Barbara Channel, California

Abstract: We have experimented with digital processing of side scan sonar data taken in a 14 sq-km area of continental shelf offshore Southern California. The data were FM tape recorded during the survey and digitized and processed later in the laboratory. The digital image processing included both image correction and image enhancement. Geometric corrections were applied to correct for image distortions due to variable ship position and speed and sonar slant range. Enhancements that were tried included contrast stretching, band-pass filtering, image restoration (inverse filtering), and various edge enhancements such as density slicing and standard deviation filters. Interpretive procedures were also attempted and included digital mosaicking, stereoscopic viewing, and falsecolor display. The most effective processing was geometric correction combined with contrast stretching. Mosaicking proved difficult due to imprecise navigation (±50 m), but was very effective in increasing the understanding of the geologic structure in the survey area.

LANDSAT-4 sensor performance

Abstract: Preflight and in-orbit sensor and data measurements indicate that TM meets or exceeds most specifications. Measured spectral band edges meet instrument specifications in 12 out of 14 cases; there is ample dynamic range. The signal-to-noise ratio exceeds specifications, except for band 3, channel 4; and band 7 channel 7 is very noisy but still meets specifications. The modulation transfer function of channel 4, band 2, is smaller than specified. Registration errors between the primary focal plane (PFP) and the cold focal plane (CFP) are about 0.75 pixels along-scan and 0.2 pixels across scan. Forward and reverse scan discontinuities, are well within ground-processing capabilities to rectify. Instrument gain variability, up to 7% for band 5, requires use of the internal calibration (IC) system to assure radiometric accuracy. Preliminary applications evaluation of image contents indicates that TM provides much better definition of edges than MSS.

A generalization of the spectrogram for colored displays

Abstract: This paper defines a class of colored displays for analyzing the spectral content of nonstationary processes. The displays are based on a natural mapping that exists between colors and pairs of zero mean, equal variance complex random variables, and are capable of representing signal features not easily recognizable on a conventional spectrogram. Displays are constructed for both one and two channel processing and an example is presented of the single channel display.