System and method for scalable portrait video

The computer-implemented process of for generating and transmitting a scalable portrait video, comprising the following process actions:

• inputting a color or full grayscale video signal;
• if an available bandwidth is between about 10-20 Kbps, then converting said input video signal to a bi-level video format, storing the input signal in bi-level video format on a physical computer-readable medium and transmitting the input signal in bi-level video format;
• and
• if the available bandwidth is between about 20-40 Kbps, hen converting said input video to a portrait video to display more grayscale levels than said bi-level video based on said available bandwidth, storing the portrait video on a physical computer-readable medium and transmitting the portrait video based on the available bandwidth, wherein generating the portrait video from the inputted color or full grayscale video, comprises the process actions of:
• for each successive frame of the color or full grayscale video:
• converting the frame of the inputted video under consideration to a full grayscale frame if the input video is a color video;
• applying a first threshold T1 to said grayscale frame to generate two partial grayscale images, a first of which, S1, comprises pixels the non-zero valued ones of which have values greater than said first threshold T1, and a second of which, S2, comprises pixels the non-zero valued ones of which have values less than said first threshold T1;
• generating a first bi-level image comprising pixels assigned the first binary value if the value of the correspondingly located pixel in the grayscale frame exceeds T1 and pixels assigned the second binary value if the value of the correspondingly located pixel in the grayscale frame is less than T1;
• applying a second threshold T21 to the first partial grayscale image, S1, to generate a second bi-level image comprising pixels assigned the first binary value if the value of the correspondingly located pixel in the first partial grayscale image exceeds T21 and pixels assigned the second binary value if the value of the correspondingly located pixel in the first partial grayscale image is less than T21;
• applying a threshold T22 to the second partial grayscale image, S2, to generate a third bi-level image comprising pixels assigned the first binary value if the value of the correspondingly located pixel in the second partial grayscale image exceeds T22 and pixels assigned the second binary value if the value of the correspondingly located pixel in the second partial grayscale image is less than T22;
• and
• combining the first, second and third bi-level images to create a four level grayscale video frame representing a frame of the portrait video.

A computer-implemented process for generating and transmitting a scalable portrait video, comprising the following process actions:

• inputting a video signal;
• if an available bandwidth is between about 10-20 Kbps, then converting said input video signal to a bi-level video format, storing the input video signal in a bi-level format on a physical computer-readable medium, and transmitting the input signal in bi-level video format;
• if the available bandwidth is between about 20-40 Kbps, then converting said input video signal to a scalable portrait video to display more grayscale levels than said bi-level video based on said available bandwidth, wherein the process action of converting the input video signal to a scalable portrait video, based on available bandwidth, further comprises the process actions of:
• obtaining a frame of video in grayscale format;
• applying a first threshold T1 to said grayscale frame to generate two partial grayscale images, a first of which, S1, comprises pixels the non-zero valued ones of which have values greater than said first threshold T1, and a second of which, S2, comprises pixels the non-zero valued ones of which have values less than said first threshold T1;
• generating a first bi-level image comprising pixels assigned a first binary value whenever the value of the correspondingly located pixel in the grayscale frame exceeds T1, and comprising pixels assigned a second binary value whenever the value of the correspondingly located pixel in the grayscale frame is less than T1;
• applying a second threshold T21 to the first partial grayscale image, S1, to generate a second bi-level image comprising pixels assigned the first binary value whenever the value of the correspondingly located pixel in the first partial grayscale image exceeds T21 and pixels assigned the second binary value whenever the value of the correspondingly located pixel in the first partial grayscale image is less than T21;
• applying a threshold T22 to the second partial grayscale image, S2, to generate a third bi-level image comprising pixels assigned the first binary value whenever the value of the correspondingly located pixel in the second partial grayscale image exceeds T22 and pixels assigned the second binary value whenever the value of the correspondingly located pixel in the second partial grayscale image is less than T22;
• encoding the first, second and third bi-level images;
• and then
• combining the first, second and third bi-level images to create a four level grayscale video frame representing a frame of the scalable portrait video;
• storing the input video signal as said scalable portrait video on a physical computer-readable medium, and transmitting the scalable portrait video.