Showing papers on "Anti-aliasing published in 1993"

Spatial anti-aliasing for animation sequences with spatio-temporal filtering

Abstract: Anti-aliasing is generally an expensive process because it requires super-sampling or sophisticated rendering. This paper presents a new type of anti-aliasing filter for animation sequences, the pixeltracing filter, that does not require any additional sample nor additional calculation in the rendering phase. The filter uses animation information to calculate correlation among the images, and sub-pixel information is extracted from the sequence based on the correlation. Theoretical studies prove that the filter becomes an ideal antialiasing filter when the filter size is infinite. The algorithm is simple image processing implemented as postfiltering. The computational cost is independent of the complexity of the scene. Experiments demonstrate the efficiency of the filter. Almost complete anti-aliasing was achieved at the rate of about 30 seconds per frame for very complex scenes at a resolution of 256x256 pixels. The pixel tracing filter provides effective antialiasing for animation sequences at a very modest computational cost. CR

Aliasing as noise: a quantitative and qualitative assessment

Abstract: We present a model-based argument that, for the purposes of system design and digital image processing, aliasing should be treated as signal-dependent additive noise. By using a computational simulation based on this model, we process (high resolution images of) natural scenes in a way which enables the 'aliased component' of the reconstructed image to be isolated unambiguously. We demonstrate that our model-based argument leads naturally to system design metrics which quantify the extent of aliasing. And, by illustrating several aliased component images, we provide a qualitative assessment of aliasing as noise.

Synchronization of digital audio with digital video

Abstract: A method for synchronization of a digital audio signal sampled at a standard audio frequency with the corresponding digital video signal sampled at a standard video frequency associates an integer number of samples of the digital audio signal with each video field of the digital video signal. The number of audio samples per video field is determined by the audio sample rate rounded up to the nearest integer. Every N video fields where the number of digital audio samples is an integer value, the digital audio signal is resynchronized with the digital video signal by repeating the digital audio samples at the end of video field N that correspond to video field N+1. At reception the same digital audio samples are skipped at the end of video field N.

Localized image compression calculating method and apparatus to control anti-aliasing filtering in 3-D manipulation of 2-D video images

Abstract: A dynamically variable anti-aliasing filtering system calculates on a local basis the compression factors (Cf) present in an image that is being mapped from a two-dimensional source image through a three-dimensional space and into a two-dimensional target image, the apparatus implementing a linear equation of the form : Cf = A*X s + B*Y s + C where, X s and Y s are, respectively, the horizontal and vertical coordinates of pixels in the source image, and A, B and C are precalculated (each field or frame) constants that depend on the transform matrix function F. A total of four compression factors are required, one for control of horizontal luminance filtering, one for control of vertical luminance filtering, one for control of horizontal chrominance filtering and one for control of vertical chrominance filtering. Three dual accumulator circuits (20,30,40) are used to implement the linear equation in X s and Y s for three different sets of A, B and C. One of these circuits measures horizontal chrominance compression, one vertical luminance compression and one compression due to skew angles. The outputs of these circuits are converted to logarithms and combined with each other and with the logarithms of multiplicative constants representing the ratios between calculated compression factors and the other required compression factor to produce those other compression factors.

Glyph rasterization method combining anti-aliasing and grid fitting

Abstract: A method for rasterizing ideal glyph representations provides improved clarity and readability for Chinese and Japanese glyphs. The preferred method advantageously combines anti-aliasing and grid fitting techniques for generating images and comprises the steps of: obtaining the ideal glyph representations and hints, converting the hint information from font units of the abstract coordinate space to pixel units, transforming the control points to pixel units using the hint information to produce a series of scaled line segments and curves, sampling points at intervals along each curve and line segment, and processing the sampled points to determine the fractional coloring for each pixel and to produce sharper transitions at those points of the glyph that have been indicated to be of aesthetic importance.

Mixed domain spectrum measurement method

Abstract: Aliasing and synchronization difficulties in determining transfer functions in mixed domain (analog and digital) systems are overcome by sampling the analog signal at a higher sampling frequency that the digital signal, and zero filling the set of sampled digital data (if necessary) so that the sampled digital data corresponds to the more densely sampled analog data. By so doing, a single fixed frequency anti-alias filter in the analog channel can be used to avoid aliasing problems in mixed domain measurements over any span of frequencies, up to the entire passband of the filter. The invention is particularly illustrated with reference to measurements both across digital-to-analog boundaries and across analog-to-digital boundaries.

Method of and apparatus for recording and/or reproducing a current digital video signal and a high-definition digital video signal in a common track format

Abstract: A digital magnetic recording method, recording apparatus, reproducing apparatus, and recording/reproducing apparatus for recording and/or reproducing a current digital video signal and a high-definition (HD) digital video signal in a common track format on a recording tape using rotary heads. In recording, the current digital video signal is compressed to a specified amount of data, the HD digital video signal is compressed to n (n is an integer of 2 or larger) times the amount of data of the compressed current digital video signal, and when recording the current digital video signal, digital audio signals of m (m is an integer of 2 or larger) channels are multiplexed with the current digital video signal in time division, and the multiplexed signal is azimuth-recorded with k (k is an integer of 2 or larger) magnetic heads on k tracks in every one revolution of the rotary drum, and when recording digital audio signals of n×m channels are multiplexed with the HD digital video signal in time division, the transportation speed of the magnetic tape is made n times the tape transportation speed in recording the current digital video signal, and the multiplexed signal is recorded by azimuth recording with n×k magnetic heads on n×k tracks in every one revolution of said rotary drum.

Digital signal processing apparatus for achieving fade-in and fade-out effects on digital video signals

Abstract: Digital signal processing apparatus in which compressed frequency components of a digital signal are processed to selectively achieve fade-in, fade-out and scene change effects and where the digital signal is scrambled (and subsequently descrambled) in whole or in by part scrambling (or descrambling) selected compressed frequency components of the digital signal.

System, apparatus and methods for recording and/or reproducing on and/or from a re-recordable record carrier digital signals containing information which results in concealment during reproduction

Abstract: Systems, apparatus and methods for recording or reproducing from a re-recordable record carrier digital signals, representing a digital audio signal, containing information which results in concealment of a portion of a replica of the digital audio signal during its reproduction to prohibit audio distortions resulting from a boundary between two digital signals, wherein one of those digital signal is newly-recorded over a previously-recorded other digital signal. The concealment information can also be included in auxiliary signals recorded on reproduced from the record carrier along with the digital signals. In a recording apparatus, a digital signal including audio information (i.e., data-reduced samples of sub-band signals derived from sub-band coding a digital audio signal, and bit allocation information and scale factor information relating to the quantized samples) is provided with, via a signal processing unit, mutilated information or a concealment code (possibly included in an auxiliary signal instead) indicating that a portion of the replica of the digital audio signal is to be concealed during its reproduction, and then, recorded on a re-recordable record carrier. The reproducing apparatus acts, via a concealment control signal and a concealment unit, as a result of the mutilated information or the concealment code included in a digital signal (or auxiliary signal) read or received from a re-recordable record carrier, to conceal a portion of the replica of the digital audio signal during its reproduction. In embodiments in which concealment codes are used, a detector is included in the reproducing apparatus to detect the concealment code.

Video signal converting apparatus with reduced processing for aliasing interference

Abstract: A video signal conversion apparatus for converting high definition television signals band-width compressed by offset sub-sampling to a conventional standard television signal while removing aliasing interference caused by offset sub-sampling and using less memory capacity than is conventionally required is provided. The image of the sub-sampled signal is restored from the sampling points in the current field by an intra-field interpolation circuit (2), and the number of scan lines is reduced to the same number in the standard television signal format by a scan line number conversion circuit (3). Half of the pixels in the current field are then substituted into the signal for the one previous frame for inter-frame interpolation by a signal selector (4) which alternately selects a signal from the scan line number conversion circuit (3) and a signal from field memories (5 and 6), and a time-base operation for removing aliasing interference at the standard television signal rate is executed.

Image signal processing apparatus for processing multiplex image signal formats

Abstract: An image signal processor for processing a received image signal. The received image signal can be at least one of an analog image signal and a digital image signal. The processor converts the analog image signal into first digital image data and converts the digital image signal to second digital image data. The processor selects at least one of the first and second digital image data as input image data. The input image data is then decode-processed based upon a selected at least one of a plurality of processing programs. The selected at least one processing program corresponds to the selected at least one of the first and second digital image data.

Subsampling of Digital Image Sequences using Motion Information

Abstract: A digital image sequence consists of a set of pixels each describing the scene intensity at a specific location on a specific instance in time. In a natural scene these pixels are spatially and temporally correlated with each other. An image coding scheme utilizes these correlations in order to represent the image sequence more efficiently in this way allowing for a more cost-effective storage or transmission. In this chapter spatio-temporal subsampling will be discussed as a data reduction technique. Subsampling is in use as a data reduction method for the standardized HDTV transmission systems MUSE [1] and HD-MAC [2] which are completely based on this technique. Recent proposals use this technique in a combination with transform coding [3][4],

Method and apparatus for evaluating audio distortion

Abstract: There is provided an improved apparatus and method which include precisely adjustable digital circuitries employing psychoacoustic modeling so that the results obtained have a best consistency with actual human auditory perception. The apparatus comprises a first estimator for estimating a power density spectrum of an input digital audio signal to the audio system; a detector for determining a masking threshold depending on the power density spectrum of the input digital audio signal as an audible limit reflecting human auditory faculty; a second estimator for estimating a power density spectrum of an error signal representative of the difference between the input digital audio signal and its output digital audio signal from the audio system; and a third estimator for estimating the power density spectrum of the error signal which exceed the masking threshold and for calculating a perceptual spectrum distance(PSD) representative of the audio distortion.

The bispectral aliasing test

Abstract: Digital signal processing of continuous signals requires sampling of the continuous signal. When sampling continuous signals it is important to avoid the effect called aliasing. Aliasing causes signals at particular frequencies to appear, erroneously, as signals of different frequencies. Consequently, it is important that before any digital signal processing is performed, the sampled signal is known to be free of aliasing. A published test based on the bispectrum purports to be able to detect aliasing of an already sampled signal. The authors provide counter examples to demonstrate that this previously published test for aliasing is not valid in practice. >

Apparatus and method for recording and reproducing digital signals by error-correcting-encoding of video and audio signals collectively

Abstract: A digital VTR is provided for recording data for one-frame of video and audio signals, which have been error-correcting-encoded collectively, in a predetermined number of pieces of tracks during normal recording and for recording data for the video and audio signals, which have been error-correcting-encoded collectively, in one less than the predetermined number of tracks and data for the audio signal, which have been error-correcting-encoded during post-scoring, in the remaining one track exclusively for the post-scoring during post-scoring audio recording.

Digital signal recording and reproducing apparatus and digital signal recording and reproducing method

Abstract: A digital VTR for recording the data of one-frame of collectively error-correcting-encoded video and audio signals in N pieces of tracks during normal recording and for recording the data of collectively, error-correcting-encoded video and audio signals in (N-1) pieces of tracks and the data of error-correction-encoded post-scoring audio signal in the remaining one track exclusively for post-scoring during post-scoring audio recording.

Method for correcting errors in digital audio data

Abstract: An improved method for correcting errors in a sequence of digital audio data for use in a system having a compact disc player device and a digital signal processor. A compact disc player device reads a compact disc and outputs digital audio data as a series of digitized samples and detects erroneous samples. An error correction apparatus implements a finite impulse response filter. The method achieves a low level of interpolation error within the corrected output of the finite impulse response filter by assigning zero-valued filter coefficients to digital audio samples that are likely to be erroneous due to their proximity to a known erroneous digital audio sample.

Digital data recording/reproducing device

Abstract: PURPOSE:To provide a digital data recording/reproducing device which can stably and surely record digital data in a digital video recorder by encoding digital data except a video on the format of a digital video signal so that it becomes optimum, adding horizontal/vertical synchronizing signals and setting them to be pseudo digital video signals CONSTITUTION:A multiplexer 10 which time base multiplexes digital audio data of plural channels on data of one channel, an ECC adder 11 adding an error correction code to data, an encoder 12 encoding digital data so that it does not coincide with the inhibition code of the digital video signal and the synchronizing signal, a data rate converter 13 converting the rate of encoded data into the data rate of the digital video signal and a horizontal/vertical synchronizing signal adder 14 adding the horizontal/vertical synchronizing signals to video signal data whose data rate is converted are provided

Motion picture films and recording and playback apparatus therefor.

Abstract: Unused areas (6) available between effective picture image areas (5) of a 35 mm motion picture film (1) are used for optically recording digital audio signals. The space for recording the digital audio signals can be sufficient to record a digital audio signal sampled with a high frequency and quantized with a large number of bits. The digital audio recording areas (6) are not subject to damage and therefore data errors are unlikely to occur.

System for recording and reproducing a digital signal on/from a re-recordable record carrier

Abstract: of EP0574071In a system for recording and reproducing a digital audio signal on/from a re-recordable record carrier, comprising a recording arrangement for recording the digital audio signal in a track on the record carrier and comprising a reproducing arrangement for reproducing the digital audio signal from the track of the record carrier, measures are provided to prevent audible distortion from occurring during a transition from a terminal portion of an original recording to a start portion of a new recording partly recorded over the original recording. This has been realized by mutilating, such as scrambling, at least part of the start portion of the new recording, so that error flags are generated during reproduction. These error flags result in a muting of the audio information which includes the audible distortion. Other ways of concealment are also possible to conceal the audible distortion. Mutilating the signal to be recorded can also mean that a concealment codeword is included indicating the transition. Upon detection of the concealment codeword, the concealment control signal is generated, resulting in a concealing of the distorted audio signal.

Method and apparatus for concealing bit errors and interpolations in digital sound signals

Abstract: During the reproduction of an audio signal, particularly of a digital audio signal, errors occur singly or continuously which can no longer be corrected by means of a corresponding data/correction system. In such a case, an interpolation is then carried out which estimates the possible signal and which cannot be perceived by the ear up to a certain degree. Such interpolation is carried out, for example, in the Sony IC CXD1167Q or Philips SAA7220 circuits. A disadvantage of these devices is the fact that the interpolation is perceived by the user up to a certain degree. It is the object of the invention to render interpolations in the audio signal inaudible. According to the invention, a method and a circuit for reproducing an audio signal is proposed which limits and/or reduces the amplitude of frequency components of the audio signal in dependence on the interpolation or error rate. Digital audio receiving, recording or reproducing devices.

Digital audio reproduction system with improved noise suppression

Abstract: A digital audio reproduction system for compact discs, digital audio tapes and other similar systems suppresses digital noise present in the frequency band immediately above the audio band. Digital preprocessing combined with narrow output filters result in significant noise suppression without adverse distortion of the desired audio signal. The digital preprocessor may be combined with digital oversampling filters into a single integrated circuit or microprocessor.

Recording and reproducing method and apparatus for a digital audio signal and a reversed bit order digital video

Abstract: A method can record or reproduce a digital audio signal and a digital video signal simultaneously. An N-bit (N: positive integer) digital audio signal is positioned at a higher bit side and an M-bit (M: positive integer) digital video signal is positioned at a lower bit side so as to form an (N+M)-bit digital signal which is recorded or reproduced in this condition. Since the digital video signal is positioned at the lower bit side, the digital video signal may not affect the reproduced audio signal even if the (N+M)-bit digital signal is processed as the digital audio signal in the reproducing process.

Method and system for performing anti-aliasing in a visual image.

Abstract: A neural network is provided and utilised to learn a relationship between a brightness and/or colour of a selected picture element and the brightness and/or colour of the surrounding picture elements. If the neural network determines that anti-aliasing would enhance the overall clarity of the graphic image the neural network then computes a scaling factor which is utilised to modify the brightness and/or colour of a selected picture element to achieve anti-aliasing. In the depicted embodiment of the present invention, a single picture element of a three by three matrix of nine picture element is modified, as required, to blur the jagged edge of a graphic image with respect to a graphic displayed in a computer system.