Showing papers on "Pixel published in 1977"

Adaptive Coding of Monochrome and Color Images

Abstract: An efficient adaptive encoding technique using a new implementation of the Fast Discrete Cosine Transform (FDCT) for bandwidth compression of monochrome and color images is described. Practical system application is attained by maintaining a balance between complexity of implementation and performance. FDCT sub-blocks are sorted into four classes according to level of image activity, measured by the total ac energy within each sub-block. Adaptivity is provided by distributing bits between classes, favoring higher levels of activity over lower levels. Excellent performance is demonstrated in terms of mean square error and direct comparison of original and reconstructed images. Results are presented for both noiseless and noisy transmission at a total rate of 1 bit and 0.5 bit per pixel for a monochrome image and for a total rate of 2 bits and 1 bit per pixel for a color image. In every case the total bit rate includes all overhead required for image reconstruction and bit protection.

Medical diagnosis system and method with multispectral imaging

Abstract: A skin diagnosis system includes a scanning and optical arrangement whereby light reflected from each incremental area (pixel) of the skin is directed simultaneously to three separate light filters, e.g., IR, red, and green. As a result the three devices simultaneously produce three signals which are directly related to the reflectance of light of different wavelengths from the corresponding pixel. These three signals for each pixel after processing are used as inputs to one or more output devices to produce a visual color display and/or a hard copy color print, for one useable as a diagnostic aid by a physician.

Interface device for encoding a digital image for a CRT display

Abstract: A display interface connected between a computer and a CRT device processes predetermined blocks of display data from predetermined locations in a memory of the computer to form pixels having predetermined characteristics in the display fields of the CRT device. A CRT display format of parameters such as color, pixel shape and size, and field shape and size, is controlled by input FORMAT DATA. The display resolution can be varied to accommodate the amount of data to be displayed within the desired field dimensions. The display data is retrieved from memory in data blocks, each of which is identified by a BLOCK ADDRESS. A single data block may occupy the entire display field; or may be displayed in a subfield simultaneously with other data blocks, or portions of data blocks, in the remaining subfields. The FORMAT DATA determines the subfield number and arrangement.

Electronic halftone screening

Abstract: An electronic signal representing the density of pixels in a scanned line in an original image and containing pixels in whole number multiples of a single line of halftone screen partial dot values plus a predetermined extension parameter is electronically halftoned by comparing the pictorial signal with the single line of halftone screen partial dot values to form an electronic halftone image. An electronic screen function represented by the single line of halftone screen values, produces automatically a rotated halftone screen at a predetermined angle to the original electronic image when the number of pixels in the input, scanned line of the original document is set equal to a whole number multiple of the number of partial-dot values plus a predetermined extension parameter. Under these conditions, the scanned input is automatically halftone screened electronically into halftone cells approximating a parallelogram and having said predetermined angle. The single line of partial-dot values need only be circularly buffered through a comparator. No electronic indexing or shifting of partial-dot values is required.

Multi-color video display systems using more than one signal source

Abstract: An improved video display system is provided in which two color images are combinable in a dynamic and self-determining fashion to provide improved contrast, comprehension and display versatility. Two separate video signals that are to be used in generating a single display are converted into sequences of digitally encoded picture elements (pixels). Control signals are generated that are dependent upon the data content of the elements in at least one of the sequences, and these signals are used to govern the mode of combination of the two video signals for individual pixel sets. For example a first video signal of digital character and having varying pixel intensity may be transformed into color values for a first pseudocolor display. A second video signal, derived from an analog source, is digitized and is also transformed into pseudocolor, concurrent with the dynamic generation in real time of the data dependent control signals. Such control signals may be incorporated in either or both of the digitized data sequences, and the second video signal may be digitized with or without adjustment of intensity ranges within variable limits. The two transformed digital signal sequences are then arithmetically or logically combined in accordance with the functions defined by the data dependent control signals. For example, the signals may be added, ANDed, ORed, averaged, subtracted, or one or the other can be blocked, and these functions can be varied, dependent upon the data, in incremental fashion within the display. Consequently, the contrast between the two color images can be selectively enhanced, the data contained in the images can be much more clearly depicted in graphical form, and special effects can be obtained in versatile and discretionary fashion.

Video correlation tracker

Abstract: A correlation tracker for generating correlation error tracking signals over an entire video frame. Video information from a scanning receiver is inputted into the correlation tracker in serial form. The correlation tracker first incorporates apparatus to generate a reference map in pixel format. Reference map pixel information for one video frame plus one video line is stored in a memory to allow the calculation of azimuth and elevation optimal weighting values for each pixel in the field of view. Each video pixel of data being received during the current frame is then summed with the corresponding reference map pixel from the prior frame and the result multiplied by the appropriate weighting function. Each resultant product is then combined in an accumulator to form azimuth and elevation correlation error signals which are composite indications of the frame-to-frame correlation over the entire field of view. The weighting factors for each pixel are also combined and accumulatively added over the entire image plane to form three adaptive scale factors at the end of each frame which are combined with the azimuth and elevation correlation error signals to eliminate cross-coupling and generate cross-coupling-free correlation error signals. Drift compensation may also be provided by combining the adaptive scale factors and several predetermined constants to recursively calculate a drift correction which when combined with the cross-coupling-free correlation error signals generates drift-free correlation error signals.

A Digital Video Acquisition System For Extraction Of Subvisual Information In Diagnostic Medical Imaging

Abstract: A system has been developed to allow single frame acquisition of superior quality digitized video images. The system consists of a high-quality x-ray image intensifier coupled to a high-resolution, low-noise video system. The output video signal is fed to a digital memory having 512 x 512 pixels and 8-bit accuracy. The memory output is directly interfaced to a PDP 11/70 image processing facility to allow computer controlled acquisition of video imagery as well as real-time visualization of computer processed images. Computer pro-cessed images are returned to the memory for display. Techniques and examples of processed radiological images will be discussed, and examples shown. Additional digital memories are under construction for 12-bit dynamic range.

Blob - An unsupervised clustering approach to spatial preprocessing of MSS imagery

Abstract: A basic concept of Multispectral Scanner data processing was developed for use in agricultural inventories; namely, to introduce spatial coordinates of each pixel into the vector description of the pixel and to use this information along with the spectral channel values in a conventional unsupervised clustering of the scene. The result is to isolate spectrally homogeneous field-like patches (called blobs). The spectral mean vector of a blob can be regarded as a defined feature and used in a conventional pattern recognition procedure. The benefits of use are: ease in locating training units in imagery; data compression of from 10 to 30 depending on the application; reduction of scanner noise and consequently potential improvements in classification/proportion estimation performances.

Half tone encoder/decoder

Abstract: A system for compressing or compacting scanned image data is disclosed. The system electronically subdivides the image data pixel pattern into quadrants and predictively encodes pictorial data by predicting, from the established image values of adjoining quadrants, an image value for each quadrant. The predicted image value is then compared with the established image value and the magnitude of the error, if any, determined. The error, if any, is then encoded to provide a relatively highly compressed description of the image suitable for transmittal, storage, and the like.

Cluster compression algorithm: A joint clustering/data compression concept

Abstract: The Cluster Compression Algorithm (CCA), which was developed to reduce costs associated with transmitting, storing, distributing, and interpreting LANDSAT multispectral image data is described. The CCA is a preprocessing algorithm that uses feature extraction and data compression to more efficiently represent the information in the image data. The format of the preprocessed data enables simply a look-up table decoding and direct use of the extracted features to reduce user computation for either image reconstruction, or computer interpretation of the image data. Basically, the CCA uses spatially local clustering to extract features from the image data to describe spectral characteristics of the data set. In addition, the features may be used to form a sequence of scalar numbers that define each picture element in terms of the cluster features. This sequence, called the feature map, is then efficiently represented by using source encoding concepts. Various forms of the CCA are defined and experimental results are presented to show trade-offs and characteristics of the various implementations. Examples are provided that demonstrate the application of the cluster compression concept to multi-spectral images from LANDSAT and other sources.

Apparatus and method for encoding halftone and line copy data

Abstract: A system for encoding halftone and line copy data having an unknown screen frequency and/or angle is disclosed. The data, in binary pixel form, is inputted to multiple predictors, each adapted to handle different types of imagery. The predictions made are compared with the established values for the pixels predicted and error signals generated. The error signals so produced are compared and the error signal with the least error is chosen for encoding.

Solid state imaging device

Abstract: A solid state imaging device capable of converting one-dimensional or two-dimensional optical information into an electrical signal is disclosed A signal charge stored in each of a plurality of photo-electric converter elements, which is proportional to the amount of incident light, is read into a corresponding stage of a charge transfer device through a switching transistor under the control of a read control pulse The read control pulse is applied through a clock line of the charge transfer device so that the clock line is used both for read-in and for transfer In this manner, one picture element of the imaging device is constructed of one photo-cell and two transistors whereby a high integration density of the solid state imaging device is attained

Peak detecting digital scan converter

Abstract: An ultrasonic multi-sector scanner performs overlapping scans such that echoes are generated by many steered beams. A peak reading digital scan converter has a random access memory with a matrix of memory cell locations corresponding to image pixels. An analog or digital comparator compares the incoming echo amplitude with the stored amplitude at an addressed memory location, and writes the incoming data into that location only when the incoming amplitude is larger. The stored largest echo amplitude data is read out in a raster at TV rates for imaging on a cathode ray tube.

Adaptive coding of monochrome and color images

Abstract: An efficient adaptive encoding technique using a new implementation of the Fast Discrete Cosine Transform (FDCT) for bandwidth compression of monochrome and color images is described. Practical system application is attained by maintaining a balance between complexity of implementation and performance. FDCT sub-blocks are sorted into four classes according to level of image activity, measured by the total ac energy within each sub-block. Adaptivity is provided by distributing bits between classes, favoring higher levels of activity over lower levels. Excellent performance is demonstrated in terms of mean square error and direct comparison of original and reconstructed images. Results are presented for both noiseless and noisy transmission at a total rate of 1 bit and 0.5 bit per pixel for a monochrome image and for a total rate of 2 bits and 1 bit per pixel for a color image. In every case the total bit rate includes all overhead required for image reconstruction and bit protection.

Adaptive Delta Modulation Systems for Video Encoding

Abstract: This paper describes several adaptive delta modulators designed to encode video signals. One- and two-dimensional ADM algorithms are discussed and compared. Results are shown for bit rates of 2 bits/pixel, 1 bit/pixel and 0.5 bits/pixel. Pictures showing the difference between the encodeddecoded pictures and the original pictures are presented. Results are also presented to illustrate the effect of channel errors on the reconstructed picture. A two-dimensional ADM using interframe encoding is also presented. This system operates at the rate of 2 bits/pixel and produces excellant quality pictures when there is little motion. We also describe and illustrate the effect of large amounts of motion on the reconstructed picture.

New Concepts in Display Technology

Abstract: As the number of image processing applications and users increases, so does the need for a low-cost image processing system. This paper describes an approach to the implementation of a solid-state image display which provides the nucleus for such a system. Combining a powerful display processor with modern random access memory refresh technology, the system features a unique "image array processor" in which entire images, instead of single pixels, may be manipulated and displayed arithmetically at video frame rates. Built on a modest budget around an LSI-11 microprocessor (see Figure 1), this system can nevertheless provide complete image processing capabilities, using the display's refresh memories for temporary image storage (in lieu of magnetic disk devices).

Spatial toner for image reconstitution

Abstract: An apparatus is described which is responsive to a sequence of received data-compacted pixels representative of a coarse two-dimensional image of a remote scene for reconstituting picture point intensity signals representative of the smoothly shading in of the coarse image. In a preferred embodiment the apparatus comprises: first means for utilizing the first one of the sequence of received data-compacted pixels to develop the initial intensity of the first one of a plurality of horizontal lines in a reconstructed image of the remote scene; second means for selectively generating horizontal and vertical gradient information as a function of the received pixels; third means selectively responsive to the initial intensity of any given horizontal line in the reconstituted image and to the associated vertical gradient information for developing by a first interpolation the initial intensity for the following horizontal line; and fourth means selectively responsive to the initial intensity of any given horizontal line and to the horizontal gradient information associated with that given horizontal line for computing a sequence of picture point intensities between each adjacent pair of received pixels in that horizontal line by a second interpolation.

Image display device

Abstract: An image display device, particularly a gas discharge image display device comprising a plurality of display elements arranged in a matrix at every picture element and a plurality of driving circuits, the display elements being composed of either radiating elements or light quantity control elements, the voltage of a gradually varying waveform such as a saw-tooth waveform being supplied to a common bus connected to the emitters of semiconductors such as FETs, bipolar transistors or the like which provide the driving circuit for controlling currents flowing through the display elements, the level whereby the driving current is clipped being continuously varied so as to control effectively the currents flowing through the display elements, and the currents being subjected to one of amplitude modulation and a combination of amplitude modulation and duty time modulation in accordance with the level of the image signal.

Video coder for color signals

Abstract: The luminance and two chrominance signals generated in a color video system are all translated into pulse code modulation signals by a plurality of analog-to-digital encoders. The luminance signal is then differentially encoded into variable length digital words and applied to a buffer. The encoded differences of the luminance signal are between the values of successive picture elements along horizontal scan lines. At least one of the chrominance signals is encoded using differences between corresponding picture element values in alternate horizontal scan lines. When the differences are large, the value of the corresponding picture element of the intermediate horizontal scan line is classified. If half the difference between the large transition of alternate picture element values does not correspond to the value of the intermediate picture element, another code word indicative of both intermediate picture element and alternate picture element is used. This improves the coding accuracy of large transitions in the chrominance signal which is also applied to the buffer. The output of the buffer is then transmitted over a channel to receiver. The receiver decodes each signal component to produce an analog replica. The chrominance signal is decoded using an interpolation technique that is also responsive to the code words indicative of both intermediate and alternate picture element values. Accordingly, the analog replica of the chrominance signal is produced which faithfully reproduces sharp color edges in the video scene.

Two-Dimensional Image Coding By Micro-Adaptive Picture Sequencing (MAPS)

Abstract: Micro-Adaptive Picture Sequencing (MAPS), a computationally-efficient contrast-adaptive variable-resolution digital image coding technique, is described. Both compression and decompression involve only integer operations with no multiplies or explicit divides. The compression step requires less than 20 operations per pixel and the decompression step even fewer. MAPS is based on the combination of a simple vision heuristic and a highly nonlinear spatial encoding. The heuristic asserts that the fine detail in an image is noticed primarily when it is sharply defined in contrast while larger more diffuse features are perceived at much lower contrasts. The coding scheme then exploits the spatial redundancy implied by this heuristic to maintain high resolution where sharp definition exists and to reduce resolution elsewhere. Application of MAPS to several imagery types with compressions extending to below 0.2 bits per pixel is illustrated.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fan beam CT apparatus with post-processing weighting of picture element signals

Abstract: In a computerized tomographic apparatus in which a wide angled, fan-shaped distribution of radiation is rotated around a body to be radiographed and detectors are provided to produce electrical output signals indicative of radiation emergent from the body along many beam paths, the signals can be sorted into sets relating to parallel sets of beam paths distributed across a cross-sectional slice of the body. However, the beam paths to which the signals so sorted relate are non-uniformly spaced beam paths, and the invention provides means whereby a processing technique known as convolution, which is of proven usefulness in computerized tomography but which, for best accuracy, operates upon output signals relating to sets of uniformly spaced, parallel beam paths, can be applied to the signals as sorted and a post-processing error compensation is effected to restore accuracy.

Generation of Precision Pixel Clock in Laser Printers and Scanners

Abstract: A new method of generating a pixel clock which can achieve fractional pixel registration across the entire film format without the need for precision servo control of the spinner motor is described. This method utilizes an auxiliary laser beam in parallel with the main writing/scanning beam. A description of several classical methods of generating precision pixel clocks for use with laser printers and laser scanners is included. The pixel placement accuracy achievable with each method is discussed along with advantages and limitations of each method. The auxiliary beam of the new method is first diverted from the writing beam just prior to its impinging the film and is then passed through an optical ruling. The modulated auxiliary beam is then collected on a photodetector. The resulting signal from the photodetector is used as a reference signal to which the pixel clock is phase locked. Generating the pixel clock in this manner not only produces accurate line-to-line pixel registration along the line, which is independent of perturbation in the scanner rotation, but also corrects for geometric distortions along the line length caused by the lens system.

Segmentation processes in the visions system

Abstract: In VISIONS the segmentation algorithms receive input from a digitized color image as an array of pixel values, and generate output as a layered graph of symbolically named regions, boundaries, and endpoints -- each with their descriptive attributes. This processed sensory data provides the initial input to the model-building system of VISIONS.

Picture signal processing system

Abstract: PURPOSE:To increase the effect caused by the data compression process by deciding the adaptability of the inversion for the binary information of the picture element pattern based on the binary information of the picture element pattern.

Color graphic display device

Abstract: PURPOSE: To secure a display of multiple colors with a reduced memory capacity in a low cost by recording multi-color information in plural registers and also memorizing the information to select the register into the memory with every picture element on the display screen. COPYRIGHT: (C)1978,JPO&Japio

The robot's eyes - Stereo vision system for automated scene analysis

Abstract: Attention is given to the robot stereo vision system which maintains the image produced by solid-state detector television cameras in a dynamic random access memory called RAPID. The imaging hardware consists of sensors (two solid-state image arrays using a charge injection technique), a video-rate analog-to-digital converter, the RAPID memory, and various types of computer-controlled displays, and preprocessing equipment (for reflexive actions, processing aids, and object detection). The software is aimed at locating objects and transversibility. An object-tracking algorithm is discussed and it is noted that tracking speed is in the 50-75 pixels/s range.

Representing a video signal upon the picture screen of a video display device

Abstract: A method and apparatus for representing the amplitude curve of a selected portion of a video signal upon the picture screen of a video display device, at least the selected portion being in digital form and not requiring conversion to analog form prior to such representation. This is achieved by using the line structure of the line raster produced on the picture screen of the video display device as a digital-analog converter. The range of possible digital values for the individual picture elements of the selected line of the video signal are allocated as reference values to respective lines of the line raster, and during each line period of the line raster the digital values of the elements are compared in succession with the appertaining reference value. When during any line period of the line raster the compared values agree the picture screen is momentarily brightened, so that each picture element of the selected line is represented on the screen with a vertical displacement determined by its digital value, so that an amplitude curve similar to an oscillogram is produced having a horizontal time axis. In a further embodiment of the invention, arranged to display the amplitude curve of selected picture elements each taken from a respective line of the video signal, the reference values are allocated to respective columns of the line raster of the display device. The result is the production of an oscillogram on the picture screen having a vertical time axis.