Patent US5543939A successfully refreshed from Google Patents.
US5543939A
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US
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Video telephone systems
Assignee: Massachusetts Institute of Technology
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Filing: 1994-09-02
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Granted: 1996-08-06
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Expires: 2014-09-02
Abstract
Abstract Differential image data compression systems and techniques are disclosed for use in video telephone systems for full duplex, real time transmission of audio and video images over nominal 3 kHz residential telephone lines and other narrow bandwidth channels. Each video telephone device consists of a transmitting portion and a receiving portion. In the transmitting section a reduced grey-scale (luminance) image, preferably consisting of only black-and-white pixels, is compared in an image processing module with a similarly reduced image derived from previous values to determine pixel positions that have changed. Information representative of the changes is then encoded and modulated and (time or frequency) multiplexed with the audio and/or chrominance signals for transmission. At the receiver, the incoming signal is demodulated and demultiplexed to separate the audio and video portions, the image portion is decoded and the luminance value is updated by an image updating unit. Adaptive resolution, pixel averaging and interpolation techniques are also disclosed for picture enhancement.
Inventors
- 👤 Robert L. Harvey
- 👤 Patrick R. Hirschler-Marchand
- 👤 David J. Cipolle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:10
CPC Classifications
H; H04; H04N; H04N19/00; H04N21/00; H04N21/20; H04N21/23; H04N21/234; H04N21/23418; H04N21/2343; H04N21/234363; H04N21/236; H04N21/23614; H04N21/238; H04N21/2383; H04N21/25; H04N21/266; H04N21/2662; H04N21/40; H04N21/43; H04N21/434; H04N21/4348; H04N21/438; H04N21/4382; H04N21/44; H04N21/4402; H04N21/440263; H04N7/00; H04N7/12
Claims Analysis
Total Claims: 63
Claim 1
Independent Claim
192 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple grey-scale image into a reduced-level grey-scale image, the dithered threshold values varying spatially across an image and temporally across plural images; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values with substantially the same number of pixel values as in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image.
Claim 2
Dependent Claim
192 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple grey-scale image into a reduced-level grey-scale image, the dithered threshold values varying spatially across an image and temporally across plural images; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values with substantially the same number of pixel values as in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image.
Claim 3
Dependent Claim
41 words
The system of claim 1 in which the encoding means further comprises a run-length encoding means for representing series of repeating differential image data bits in a coded fashion, such that long series of said bits are represented by fewer bits.
Claim 4
Dependent Claim
34 words
The system of claim 1 wherein the system further includes an adaptive resolution means for determining a level of motion in successive image frames and for modifying spatial resolution in response to such determination.
Claim 5
Dependent Claim
217 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple grey-scale image into a reduced-level grey-scale image; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values with substantially the same number of pixel values as in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and wherein the dithered threshold values comprise sets of values varying spatially across an image, different sets representing different spatial resolutions, the system further comprising a resolution selector to select a set of dithered threshold values for the threshold means.
Claim 6
Dependent Claim
217 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple grey-scale image into a reduced-level grey-scale image; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values with substantially the same number of pixel values as in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and wherein the dithered threshold values comprise sets of values varying spatially across an image, different sets representing different spatial resolutions, the system further comprising a resolution selector to select a set of dithered threshold values for the threshold means.
Claim 7
Dependent Claim
36 words
The system of claim 4 in which the dithered threshold means further comprises a hysteresis adjustment in which a threshold value applied to each pixel is modified in order to reduce toggling of the pixel value.
Claim 8
Dependent Claim
34 words
The system of claim 5 in which the system further comprises means for varying the hysteresis adjustment when a data rate of the encoded difference signal exceeds a limited bandwidth of a transmission medium.
Claim 9
Dependent Claim
173 words
In a signal processing apparatus for decoding and reconstructing a video image from received compressed image data, a system comprising: a differential image decoding unit for decoding a difference signal representative of changes in a reduced grey-scale image from one frame to the next; an image updating unit for updating changes to a previously stored image by adding said decoded difference signal to said previously stored image and thereby obtaining an updated image of reduced grey-scale pixel values; and an image reconstruction unit for expanding each reduced grey-scale pixel value for each reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image, to increase the number of grey levels of said updated image with substantially the same number of pixel values as in the reduced grey-scale image, wherein the blocks of pixel values include pixel values from plural updated images for both spatial and temporal averaging.
Claim 10
Dependent Claim
173 words
In a signal processing apparatus for decoding and reconstructing a video image from received compressed image data, a system comprising: a differential image decoding unit for decoding a difference signal representative of changes in a reduced grey-scale image from one frame to the next; an image updating unit for updating changes to a previously stored image by adding said decoded difference signal to said previously stored image and thereby obtaining an updated image of reduced grey-scale pixel values; and an image reconstruction unit for expanding each reduced grey-scale pixel value for each reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image, to increase the number of grey levels of said updated image with substantially the same number of pixel values as in the reduced grey-scale image, wherein the blocks of pixel values include pixel values from plural updated images for both spatial and temporal averaging.
Claim 11
Dependent Claim
20 words
The system of claim 7 which further comprises an image interpolating unit for generating a more detailed image by interpolation.
Claim 12
Independent Claim
181 words
A method of signal processing for image data compression, the method comprising: reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; reconstructing an expanded-level grey-scale image from the luminance difference signal with substantially the same number of pixel values in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values for the step of comparing.
Claim 13
Independent Claim
181 words
A method of signal processing for image data compression, the method comprising: reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; reconstructing an expanded-level grey-scale image from the luminance difference signal with substantially the same number of pixel values in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values for the step of comparing.
Claim 14
Dependent Claim
26 words
The method of claim 9 in which the step of reducing the number of grey levels comprises converting a multiple grey-scale image into a halftone image.
Claim 15
Dependent Claim
34 words
The method of claim 9 in which the step of comparing a dithered threshold value further comprises applying a hysteresis adjustment to said threshold value in order to reduce toggling of the pixel value.
Claim 16
Dependent Claim
26 words
The method of claim 11 in which the method further comprises varying the hysteresis adjustment in response to the data rate of the encoded difference signal.
Claim 17
Dependent Claim
35 words
The method of claim 9 in which the step of encoding the luminance difference signal further comprises run-length encoding said signal such that commonly repeated series of image data bits are assigned shorter code words.
Claim 18
Independent Claim
186 words
A method of signal processing for image data compression, the method comprising: reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; reconstructing an expanded-level grey-scale image from the luminance difference signal with substantially the same number of pixel values in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and storing dithered threshold values varying spatially across an image and temporally across plural images, and performing the step of comparing based on the spatially and temporally varying dithered threshold values.
Claim 19
Independent Claim
186 words
A method of signal processing for image data compression, the method comprising: reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; reconstructing an expanded-level grey-scale image from the luminance difference signal with substantially the same number of pixel values in the reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image; and storing dithered threshold values varying spatially across an image and temporally across plural images, and performing the step of comparing based on the spatially and temporally varying dithered threshold values.
Claim 20
Dependent Claim
32 words
The method of claim 14 further comprising storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values for the step of comparing.
Claim 21
Dependent Claim
91 words
A dithered threshold system for generating reduced grey-scale video images comprising: sets of stored three dimensional arrays of dithered threshold values, each varying spatially across an image and varying temporally across plural images as an integral block of related dithered threshold values, different sets representing different resolutions; threshold means for comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and a resolution selector for selecting a set of stored dithered threshold values for the threshold means.
Claim 22
Dependent Claim
91 words
A dithered threshold system for generating reduced grey-scale video images comprising: sets of stored three dimensional arrays of dithered threshold values, each varying spatially across an image and varying temporally across plural images as an integral block of related dithered threshold values, different sets representing different resolutions; threshold means for comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and a resolution selector for selecting a set of stored dithered threshold values for the threshold means.
Claim 23
Dependent Claim
96 words
A dithered threshold system for generating reduced grey-scale video images comprising: a stored three dimensional array of dithered threshold values varying spatially across an image and varying temporally across plural images as an integral block of related dithered threshold values; threshold means for comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and a reconstruction means for generating an expanded-level grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 24
Dependent Claim
96 words
A dithered threshold system for generating reduced grey-scale video images comprising: a stored three dimensional array of dithered threshold values varying spatially across an image and varying temporally across plural images as an integral block of related dithered threshold values; threshold means for comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and a reconstruction means for generating an expanded-level grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 25
Dependent Claim
46 words
The system of claim 17 wherein the stored three dimensional array of dithered threshold values further comprise sets of dithered threshold values, different sets representing different resolutions, and further comprising a resolution selector for selecting a set of stored dithered threshold values for the threshold means.
Claim 26
Dependent Claim
19 words
The system of claim 18 wherein the resolution selector comprises a motion detector for detecting motion between successive images.
Claim 27
Dependent Claim
21 words
The system of claim 19 wherein the motion detector detects motion based on a count of pixels which vary between images.
Claim 28
Dependent Claim
29 words
The system of claim 17 wherein the reconstruction means averages pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value.
Claim 29
Dependent Claim
70 words
A dithered threshold system for generating a reduced-level grey-scale image comprising: stored sets of dithered threshold values varying spatially across an image, different sets representing different spatial resolutions; a resolution selector comprising a motion detector for detecting motion between successive images; and threshold means for comparing grey-scale image pixel values to a set of stored dithered threshold values selected by the resolution selector to generate reduced grey-scale image pixel values.
Claim 30
Dependent Claim
70 words
A dithered threshold system for generating a reduced-level grey-scale image comprising: stored sets of dithered threshold values varying spatially across an image, different sets representing different spatial resolutions; a resolution selector comprising a motion detector for detecting motion between successive images; and threshold means for comparing grey-scale image pixel values to a set of stored dithered threshold values selected by the resolution selector to generate reduced grey-scale image pixel values.
Claim 31
Dependent Claim
23 words
The system of claim 22 wherein the stored sets of dithered threshold values vary spatially across an image and temporally across plural images.
Claim 32
Dependent Claim
21 words
The system of claim 22 wherein the motion detector detects motion based on a count of pixels which vary between images.
Claim 33
Independent Claim
95 words
A method of generating reduced video grey-scale images comprising: storing sets of three dimensional arrays of dithered threshold values, each as an integral block of related dithered threshold values which vary spatially across an image and temporally across plural images, different sets representing different resolutions; and comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstructing an expanded grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 34
Independent Claim
95 words
A method of generating reduced video grey-scale images comprising: storing sets of three dimensional arrays of dithered threshold values, each as an integral block of related dithered threshold values which vary spatially across an image and temporally across plural images, different sets representing different resolutions; and comparing grey-scale image pixel values of a sequence of video images to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstructing an expanded grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 35
Independent Claim
68 words
The method of generating reduced grey-scale video images comprising: storing sets of dithered threshold values varying spatially across an image, different sets representing different spatial resolution; selecting a set of dithered threshold values based on changes between successive video image frames which indicate movement between frames; and comparing grey-scale image pixel values to a selected set of stored dithered threshold values to generate reduced grey-scale image pixel values.
Claim 36
Independent Claim
68 words
The method of generating reduced grey-scale video images comprising: storing sets of dithered threshold values varying spatially across an image, different sets representing different spatial resolution; selecting a set of dithered threshold values based on changes between successive video image frames which indicate movement between frames; and comparing grey-scale image pixel values to a selected set of stored dithered threshold values to generate reduced grey-scale image pixel values.
Claim 37
Dependent Claim
208 words
In a signal processing apparatus for image data compression, a system comprising: stored sets of dithered threshold values varying spatially across an image and temporally across plural images, different sets representing different spatial resolutions; a resolution selector for selecting resolution based on content of successive grey-scale images; dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert the multiple-level grey-scale image into a reduced-level grey-scale image; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from the storage means, and for generating a luminous difference signal representative of changes in the reduced grey-scale pixel values between image frames; run length encoding means for encoding the difference signal for transmission through a limited bandwidth transmission system; decoding means; and reconstruction means for generating an increased grey-scale image from the luminous difference signal, the reconstruction means including an averaging unit for expanding the grey-scale pixel values for each reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value, to increase the number of grey levels of a reconstructed image.
Claim 38
Dependent Claim
208 words
In a signal processing apparatus for image data compression, a system comprising: stored sets of dithered threshold values varying spatially across an image and temporally across plural images, different sets representing different spatial resolutions; a resolution selector for selecting resolution based on content of successive grey-scale images; dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert the multiple-level grey-scale image into a reduced-level grey-scale image; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from the storage means, and for generating a luminous difference signal representative of changes in the reduced grey-scale pixel values between image frames; run length encoding means for encoding the difference signal for transmission through a limited bandwidth transmission system; decoding means; and reconstruction means for generating an increased grey-scale image from the luminous difference signal, the reconstruction means including an averaging unit for expanding the grey-scale pixel values for each reduced grey-scale image by averaging pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value, to increase the number of grey levels of a reconstructed image.
Claim 39
Dependent Claim
105 words
A signal processing apparatus for expanding an image from reduced grey-scale image data comprising: storage of pixel values of a reduced grey-scale image; and an image expander for expanding each reduced grey-scale pixel value by averaging pixel values of respective blocks of pixel values, including pixel values from plural updated images for both spatial and temporal averaging, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image, to increase the number of grey levels of each pixel with substantially the same number of pixel values as in the reduced grey-scale image.
Claim 40
Dependent Claim
105 words
A signal processing apparatus for expanding an image from reduced grey-scale image data comprising: storage of pixel values of a reduced grey-scale image; and an image expander for expanding each reduced grey-scale pixel value by averaging pixel values of respective blocks of pixel values, including pixel values from plural updated images for both spatial and temporal averaging, a different block of pixel values for each expanded pixel value defined by a shifting window over pixel values of the reduced grey-scale image, to increase the number of grey levels of each pixel with substantially the same number of pixel values as in the reduced grey-scale image.
Claim 41
Dependent Claim
139 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values, which vary spatially across an image and temporally across plural images, to multiple-level grey-scale images to convert said multiple grey-scale images into reduced-level grey-scale images; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values.
Claim 42
Dependent Claim
139 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values, which vary spatially across an image and temporally across plural images, to multiple-level grey-scale images to convert said multiple grey-scale images into reduced-level grey-scale images; storage means for storing a reference reduced grey-scale image derived from image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values.
Claim 43
Dependent Claim
164 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple-level grey-scale image into a reduced-level grey-scale image, the dithered threshold values comprising sets of values varying spatially across an image, different sets representing different spatial resolutions; a resolution selector to select a set of dithered threshold values for the threshold means; storage means for storing a reference reduced grey-scale image derived for image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values.
Claim 44
Dependent Claim
164 words
In a signal processing apparatus for video image data compression, a system comprising: dithered threshold means for applying dithered threshold values to a multiple-level grey-scale image to convert said multiple-level grey-scale image into a reduced-level grey-scale image, the dithered threshold values comprising sets of values varying spatially across an image, different sets representing different spatial resolutions; a resolution selector to select a set of dithered threshold values for the threshold means; storage means for storing a reference reduced grey-scale image derived for image pixel values; comparison means for comparing a reduced grey-scale image of a current image frame with a reference image from said storage means, and for generating a luminance difference signal representative of the changes in reduced grey-scale pixel values between image frames; encoding means for encoding said difference signal for transmission through a transmission system; decoding means; and reconstruction means for generating an expanded grey-scale image from the luminance difference signal having expanded levels from the reduced grey-scale image pixel values.
Claim 45
Dependent Claim
36 words
The system of claim 30 in which the dithered threshold means further comprises a hysteresis adjustment in which a threshold value applied to each pixel is modified in order to reduce toggling of the pixel value.
Claim 46
Dependent Claim
34 words
The system of claim 31 in which the system further comprises means for varying the hysteresis adjustment when a data rate of the encoded difference signal exceeds a limited bandwidth of a transmission medium.
Claim 47
Dependent Claim
145 words
In a signal processing apparatus for decoding and reconstructing a video image from received compressed image data, a system comprising: a differential image decoding unit for decoding a difference signal representative of changes in a reduced grey-scale image from one frame to the next; an image updating unit for updating changes to a previously stored image by adding said decoded difference signal to said previously stored image and thereby obtaining an updated image of reduced grey-scale pixel values; and an image reconstruction unit for expanding each reduced grey-scale pixel value for each reduced grey-scale image by combining pixel values of respective blocks of pixel values, each block including pixel values from plural updated images for both spatial and temporal averaging and there being a different block of pixel values for each expanded pixel value, to increase the number of grey levels of said updated image.
Claim 48
Dependent Claim
145 words
In a signal processing apparatus for decoding and reconstructing a video image from received compressed image data, a system comprising: a differential image decoding unit for decoding a difference signal representative of changes in a reduced grey-scale image from one frame to the next; an image updating unit for updating changes to a previously stored image by adding said decoded difference signal to said previously stored image and thereby obtaining an updated image of reduced grey-scale pixel values; and an image reconstruction unit for expanding each reduced grey-scale pixel value for each reduced grey-scale image by combining pixel values of respective blocks of pixel values, each block including pixel values from plural updated images for both spatial and temporal averaging and there being a different block of pixel values for each expanded pixel value, to increase the number of grey levels of said updated image.
Claim 49
Independent Claim
137 words
A method of signal processing for image data compression, the method comprising: storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values; reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value of the selected set of dithered threshold values to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; and reconstructing an expanded-level grey-scale image from the luminance difference signal.
Claim 50
Independent Claim
137 words
A method of signal processing for image data compression, the method comprising: storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values; reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value of the selected set of dithered threshold values to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; and reconstructing an expanded-level grey-scale image from the luminance difference signal.
Claim 51
Independent Claim
132 words
A method of signal processing for image data compression, the method comprising: storing dithered threshold values varying spatially across an image and temporally across plural images; reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value of the spatially and temporally varying dithered threshold values to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; and reconstructing an expanded-level grey-scale image from the luminance difference signal.
Claim 52
Independent Claim
132 words
A method of signal processing for image data compression, the method comprising: storing dithered threshold values varying spatially across an image and temporally across plural images; reducing the number of grey levels available to represent each pixel of an image frame by comparing a dithered threshold value of the spatially and temporally varying dithered threshold values to the luminance value of each pixel, and assigning the pixel a reduced grey-scale value based upon the comparison; storing a reference reduced grey-scale image derived from image pixel values; comparing a reduced grey-scale image of a current image frame with a previously stored reference reduced grey-scale image; generating a luminance difference signal representative of changes in the reduced grey-scale pixel values between image frames; and reconstructing an expanded-level grey-scale image from the luminance difference signal.
Claim 53
Dependent Claim
32 words
The method of claim 35 further comprising storing sets of dithered threshold values, different sets representing different spatial resolutions, and selecting a set of dithered threshold values for the step of comparing.
Claim 54
Dependent Claim
74 words
A dithered threshold system for generating a reduced grey-scale image comprising: stored dithered threshold values varying spatially across an image and temporally across plural images; threshold means for comparing grey-scale image pixel values to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstruction means for generating an expanded-level grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 55
Dependent Claim
74 words
A dithered threshold system for generating a reduced grey-scale image comprising: stored dithered threshold values varying spatially across an image and temporally across plural images; threshold means for comparing grey-scale image pixel values to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstruction means for generating an expanded-level grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 56
Dependent Claim
42 words
The system of claim 37 wherein the stored dithered threshold values further comprise sets of dithered threshold values, different sets representing different resolutions, and further comprising a resolution selector for selecting a set of stored dithered threshold values for the threshold means.
Claim 57
Dependent Claim
19 words
The system of claim 38 wherein the resolution selector comprises a motion detector for detecting motion between successive images.
Claim 58
Dependent Claim
21 words
The system of claim 39 wherein the motion detector detects motion based on a count of pixels which vary between images.
Claim 59
Dependent Claim
29 words
The system of claim 37 wherein the reconstruction means averages pixel values of respective blocks of pixel values, a different block of pixel values for each expanded pixel value.
Claim 60
Independent Claim
73 words
A method of generating a reduced grey-scale image comprising: storing sets of dithered threshold values representing different spatial resolutions which vary spatially across an image and temporally across plural images; comparing grey-scale image pixel values to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstructing an expanded grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 61
Independent Claim
73 words
A method of generating a reduced grey-scale image comprising: storing sets of dithered threshold values representing different spatial resolutions which vary spatially across an image and temporally across plural images; comparing grey-scale image pixel values to the stored dithered threshold values to generate reduced grey-scale image pixel values; and reconstructing an expanded grey-scale image by combining reduced grey-scale image pixel values across a spatially and temporally extending block of reduced grey-scale pixel values.
Claim 62
Dependent Claim
83 words
A signal processing apparatus for expanding an image from reduced grey-scale image data comprising: storage of pixel values of a reduced grey-scale image; and an image expander for expanding each reduced grey-scale pixel value by combining pixel values of respective blocks of pixel values, each block including pixel values from plural updated images for both spatial and temporal averaging and there being a different block of pixel values for each expanded pixel value, to increase the number of grey levels of each pixel.
Claim 63
Dependent Claim
83 words
A signal processing apparatus for expanding an image from reduced grey-scale image data comprising: storage of pixel values of a reduced grey-scale image; and an image expander for expanding each reduced grey-scale pixel value by combining pixel values of respective blocks of pixel values, each block including pixel values from plural updated images for both spatial and temporal averaging and there being a different block of pixel values for each expanded pixel value, to increase the number of grey levels of each pixel.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-08-06 | 2000-02-05 | 2000-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-06 | 2004-02-05 | 2004-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-06 | 2008-02-05 | 2008-08-06 | $7700.00 | Window Closed / Lapsed |