Abstract: A general method is provided to achieve frequency conversion in an all-digital frequency conversion device that produces an output signal having a selectable phase and frequency that is substantially synchronous with the input signal to be converted. A multiplicity of time-shifted signals is generated, and appropriate ones are selected to set and reset an output signal. An apparatus, computing system, and software product that implement the present invention are also provided.

Abstract: An all-digital frequency conversion apparatus is provided that achieves frequency conversion using a simple phase detector and integer and fractional phase feedback information from a digital oscillator output. In an embodiment, a target phase accumulator unit generates a target phase signal to the phase detector unit. The target phase accumulator unit receives inputs from a reference signal input, and a target phase input value. The digital phase detector unit receives the reference signal, a current phase feedback input signal, and the target phase input signal. The phase detector unit outputs a frequency setting signal to a frequency value generator unit. The detector output is based on the difference between the current phase and the target phase. A frequency value generator unit is configured to output a frequency value signal to a digital oscillator unit that generates a corresponding digital output signal that is directly fed back to the current phase feedback input of the phase detector unit.

Abstract: A method and apparatus for reducing the appearance of moiré in a digitally resized image wherein each input pixel value is mapped to a new value by means of a first correction function prior to being resized. At the output of the resizing engine, each pixel in the resized image is mapped to a further new value by means of a second correction function prior to being displayed. The second correction function is chosen such that the intensity of light output from the display device is substantially proportional to the value of the signal from the resizing engine, taking into account the combined transfer functions of the second correction means and the physical display device (i.e. the second correction function is substantially the inverse of the display transfer characteristic).

Abstract: A programmable delay element is provided for delaying a digital input signal. The programmable delay element comprises a discharge capacitor adapted to be precharged to a predetermined voltage in response to a first transition of the digital input signal. A transistor switch of a first type is provided for precharging the discharge capacitor to a predetermined voltage. A discharge current source is connected via a sense node to the discharge capacitor for discharging the capacitor in response to a subsequent opposite transition of the digital input signal. A transistor switch of a second type is provided for connecting the discharge capacitor to the discharge current source and thereby discharging the discharge capacitor. A reference voltage source is provided for applying a reference voltage to a reference node.

Abstract: A method of de-interlacing used to convert an interlaced video signal to a progressively scanned format utilizing vertical temporal filtering to generate the missing lines, utilizing appropriate filter coefficients to give a desired vertical frequency response, and filter utilizing coefficients such that the total combined contribution from all fields is unity while the total contribution from each individual field is chosen so as to boost higher temporal frequencies which has the perceived effect of increasing the sharpness of moving edges. Furthermore, in order to avoid certain unwanted artifacts, the lines of the current field are modified using a vertical temporal filter with similar temporal boosting properties to that which was used to generate the missing lines.

Abstract: A method of generating an upsampled target pixel positioned between two lines of input source data includes the step of comparing pixels of different lines of the source data in a region surrounding the upsampled target pixel to be generated in at least two different directions. An interpolation direction based on the comparison is selected and interpolations between selected pixels of the source data in the determined interpolation direction are carried out to compute intermediate pixels on a line segment passing through the upsampled target pixel. An interpolation between the intermediate pixels is carried out to generate the upsampled target pixel. An apparatus for performing the method is also disclosed.

Abstract: A method and apparatus are provided for converting interlaced video fields of arbitrary size to progressive scan format video frames of arbitrary size. The method and apparatus of the invention provide consistent conversion quality even while output video dimensions are scaled in real-time. According to a first aspect of the invention the space between output lines is calculated with respect to the input fields. According to a second aspect, the output line spacing information is used to calculate the final line positions in a progressive scan output frame.

Abstract: A method of generating an upsampled target pixel positioned between two lines of input source data includes the step of comparing pixels of different lines of the source data in a region surrounding the upsampled target pixel to be generated in at least two different directions. An interpolation direction based on the comparison is selected and interpolations between selected pixels of the source data in the determined interpolation direction are carried out to compute intermediate pixels on a line segment passing through the upsampled target pixel. An interpolation between the intermediate pixels is carried out to generate the upsampled target pixel. An apparatus for performing the method is also disclosed.

Abstract: A circuit for filtering an input digital image comprising: first storage apparatus for storing the input digital image; apparatus for retrieving the input digital image from the first storage apparatus and generating a first resized digital image of reduced spatial frequency relative to the input digital image and being of smaller size than the input digital image; second storage apparatus for storing the first resized digital image; apparatus for retrieving the first resized digital image from the second storage apparatus and generating a second resized digital image of equal size to the input digital image, wherein the second resized digital image is a low-pass filtered version of the input digital image due to the reduced spatial frequency of the first resized digital image; and third storage apparatus for storing the second resized digital image.

Abstract: A system is provided for performing real-time warping in one or two dimensions (eg. dynamic zoom and shrink in both horizontal and vertical directions), and temporal warping of image frames (eg. fast motion and slow motion). The system accomplishes warping with proper Nyquist bandlimiting. Three different processes are performed in sequence to create the warped image according to the present invention. The first process maps a desired target pixel or frame spacing to an appropriate FIR filter wherein the size of the FIR filter is chosen based on the desired target pixel or frame spacing. Once the filter is chosen, a second process creates an appropriate number of upsampled pixels, lines or frames based on the input source pixels, lines or frames. The last process multiplies the correct filter coefficients from the first process with the interpolated pixels, lines or frames from the second process, resulting in correctly Nyquist bandlimited target pixels, lines or frames.

Abstract: In an apparatus for resizing an image, comprising interpolation filter means for receiving a stream of input pixels having a predetermined sampling period P and a first sampling rate of S pixels/lines, and interpolating the stream of input pixels at a predetermined interpolation rate for generating a first derived sample stream of pixels having a further sampling period (M/(CL))P and a second sampling rate of T pixels/lines, where L is a first positive integer greater than one, C is a positive integer and M is smaller than CL, and where either 2.sup.n M/CL or 2.sup.

Abstract: A decimator for effecting a X:1 decimation, where X=is any positive integer greater than 1, comprising a FIR filter for receiving and filtering an input stream of data bits and in response generating a like number of filtered output data bits; and a hold circuit for sampling and outputting every Xth one of the filtered output data bits.

Abstract: A method of signal sample interpolation utilizing a second order curve utilizing a linear interpolator to select a mid-point between respective input samples, eliminating phase error and spatial variation, utilizing the interpolated points as reference points for a quadratic interpolation wherein the space between the reference points is one half the distance between respective signal sample points, and thirdly combining the operations of linear interpolation and quadratic interpolation for simultaneous execution. More particularly, the quadratic interpolation is reformed based on the output of the linear interpolation.

Abstract: A digital filter characterized by a plurality of filter coefficients, positive ones of the coefficients being represented by unsigned binary integers and negative ones of the coefficients being represented by 2's complement binary integers, comprising an input for receiving a digital input signal comprising a first predetermined number of bits; means for truncating or rounding at least one leading "0" or trailing "0" of the positive ones of the coefficients and at least one leading "1" or trailing "0" of the negative ones of the coefficients, such that significance of the integers is removed; means for successively delaying the digital input signal to produce successively delayed versions of the digital input signal; means for multiplying the successively delayed versions of the digital input signal by respective ones of the truncated representations of the respective ones of the plurality of filter coefficients and in response generating a plurality of intermediate product integers; means for restoring signi

Abstract: In a multi-rate digital signal processing system for re-sizing an image in at least two segments using at least two symmetric T-tap digital filters each having T kernel-function weighting coefficients, where T is an odd plural integer, a first one of the segments being characterized by a first plurality of unfiltered pixels and second adjacent one of the segments being characterized by a second plurality of unfiltered pixels, a predetermined one of the unfiltered pixels being common to both the first and the second plurality at the image boundary of the two segments, the improvement comprising a method of seamlessly extending the image across the image boundary, comprising the steps of multiplying the (T-1)/2 of the first plurality and the second plurality of the unfiltered pixels adjacent the predetermined one of the pixels by two times respective ones of the kernel function weighting coefficients for generating the first and second mirrored half kernel intermediate multiplication products; multiplying the p

Abstract: A method of signal sample interpolation utilizing a second order curve comprising the steps of utilizing a linear interpolator to select a mid-point between respective input samples, thereby eliminating phase error and spatial variation, utilizing the interpolated points as reference points for a quadratic interpolation wherein the space between the reference points is one half the distance between respective signal sample points, and thirdly combining the operations of linear interpolation and quadratic interpolation for simultaneous execution. More particularly, the quadratic interpolation is reformed based on the output of the linear interpolation.

Abstract: A circuit for filtering an input digital image comprising: first storage apparatus for storing the input digital image; apparatus for retrieving the input digital image from the first storage apparatus and generating a first resized digital image of reduced spatial frequency relative to the input digital image and being of smaller size than the input digital image; second storage apparatus for storing the first resized digital image; apparatus for retrieving the first resized digital image from the second storage apparatus and generating a second resized digital image of equal size to the input digital image, wherein the second resized digital image is a lowpass filtered version of the input digital image due to the reduced spatial frequency of the first resized digital image; and third storage apparatus for storing the second resized digital image.