System and process for broadcast and communication with very low bit-rate bi-level or sketch video
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Abstract
A system and process for broadcast and communication with bi-level or sketch video at extremely low bandwidths is described. Essentially, bi-level and sketch video presents the outlines of the objects in a scene being depicted. Bi-level and sketch video provides a clearer shape, smoother motion, shorter initial latency and cheaper computational cost than do conventional DCT-based video compression methods. This is accomplished by converting each color or gray-scale image frame to bi-level or sketch image frame using adaptive thresholding method, compressing bi-level or sketch image frames into bi-level or sketch video using adaptive context-based arithmetic coding method. Bi-level or sketch video is particularly suitable to such small devices as Pocket PCs and mobile phones that possess small display screen, low bandwidth connection, and light computational power.
184 Citations
79 Claims
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1-59. -59. (canceled)
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60. A system for generating a bi-level video, comprising:
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a general purpose computing device;
a computer program comprising program modules executable by the computing device, wherein the computing device is directed by the program modules of the computer program to, input digitized video comprising a sequence of video image frames, convert the input video image frames into bi-level image frames, wherein the digitized video is characterized by pixels defined in terms either a color level or a gray scale level, and wherein said conversion comprises, ascertaining whether the input video image frames comprises pixels defined in terms of a color level, and converting each input video image frame so as to define each pixel thereof in terms of one of a plurality of gray scale levels so as to produce a gray scale image frame whenever the pixels are defined in terms of color levels, wherein the particular gray scale level selected to define a pixel is based on the color level of that pixel, such that this converting comprises, computing a threshold gray scale level, assigning a first of two bi-level image frame colors to those pixels that exhibit a gray scale level exceeding said threshold by a prescribed upper-limit amount, assigning the second of said two colors to those pixel exhibiting a gray scale level that is less than said threshold by a prescribed lower-limit amount, and associating an indicator with those pixels that exhibit a gray scale level which does not exceed said threshold by the upper-limit amount and which are not less than said threshold by the lower-limit amount, wherein one of the two bi-level image frame colors is assigned to the pixels having said indicator associated therewith based on a predicted value established for the pixel as part of the performance of the process action for encoding the bi-level image frames, and encode the bi-level image frames. - View Dependent Claims (61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77)
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78. A computer-implemented process for generating a bi-level video, comprising:
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an inputting step for inputting digitized video comprising a sequence of video image frames;
a converting step for converting the input video image frames into bi-level image frames, wherein the digitized video is characterized by pixels defined in terms either a color level or a gray scale level, and wherein said conversion step comprises, an ascertaining step for ascertaining whether the input video image frames comprises pixels defined in terms of a color level, and a converting step for converting each input video image frame so as to define each pixel thereof in terms of one of a plurality of gray scale levels so as to produce a gray scale image frame whenever the pixels are defined in terms of color levels, wherein the particular gray scale level selected to define a pixel is based on the color level of that pixel, such that this converting step comprises, a computing step for computing a threshold gray scale level, a first assigning step for assigning a first of two bi-level image frame colors to those pixels that exhibit a gray scale level exceeding said threshold by a prescribed upper-limit amount, a second assigning step for assigning the second of said two colors to those pixel exhibiting a gray scale level that is less than said threshold by a prescribed lower-limit amount, and an associating step for associating an indicator with those pixels that exhibit a gray scale level which does not exceed said threshold by the upper-limit amount and which are not less than said threshold by the lower-limit amount, wherein one of the two bi-level image frame colors is assigned to the pixels having said indicator associated therewith based on a predicted value established for the pixel as part of the performance of the process action for encoding the bi-level image frames; and
an encoding step for encoding the bi-level image frames.
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79. A computer-readable medium having computer-executable instructions for generating a bi-level video, said computer-executable instructions comprising:
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inputting digitized video comprising a sequence of video image frames;
converting the input video image frames into bi-level image frames, wherein the digitized video is characterized by pixels defined in terms either a color level or a gray scale level, and wherein said conversion instruction comprises, ascertaining whether the input video image frames comprises pixels defined in terms of a color level, and converting each input video image frame so as to define each pixel thereof in terms of one of a plurality of gray scale levels so as to produce a gray scale image frame whenever the pixels are defined in terms of color levels, wherein the particular gray scale level selected to define a pixel is based on the color level of that pixel, such that this converting instruction comprises, computing a threshold gray scale level, assigning a first of two bi-level image frame colors to those pixels that exhibit a gray scale level exceeding said threshold by a prescribed upper-limit amount, assigning the second of said two colors to those pixel exhibiting a gray scale level that is less than said threshold by a prescribed lower-limit amount, and associating an indicator with those pixels that exhibit a gray scale level which does not exceed said threshold by the upper-limit amount and which are not less than said threshold by the lower-limit amount, wherein one of the two bi-level image frame colors is assigned to the pixels having said indicator associated therewith based on a predicted value established for the pixel as part of the performance of the process action for encoding the bi-level image frames; and
encoding the bi-level image frames.
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Specification