A video compression system is disclosed that is optimized to take advantage of the types of redundancies typically occurring on computer screens and the types of video loss acceptable to real time interactive computer users. It automatically adapts to a wide variety of changing network bandwidth conditions and can accommodate any video resolution and an unlimited number of colors. The disclosed video compression encoder can be implemented with either hardware or software and it compresses the source video into a series of data packets that are a fixed length of 8 bits or more. Sequences of one or more of these packets create unique encoding “commands” that can be sent over any network and easily decoded (decompressed) with either software or hardware. The commands include 3 dimensional copying (horizontal, vertical and time) and unique efficiencies for screen segments that are comprised of only two colors (such as text). Embodiments are also disclosed that improve the video compression depending on the popularity of pixel colors.

A method for encoding a series of symbols using several models of the arithmetic or range coder type and including steps where each model is associated with a belonging criterion, the series is run through in order to determine, for each symbol, the encoding model to which each symbol belongs, according to the criteria; then a probability of occurrence of each symbol in the corresponding model is determined; then the series is run through by encoding each symbol successively; and a file is formed from the code thus obtained.

A method for encoding a series of symbols using several models of the arithmetic or range coder type and including steps where each model is associated with a belonging criterion, the series is run through in order to determine, for each symbol, the encoding model to which each symbol belongs, according to the criteria; then a probability of occurrence of each symbol in the corresponding model is determined; then the series is run through by encoding each symbol successively; and a file is formed from the code thus obtained.

Various examples are provided for lossless compression of data streams. In one example, a Z-lossless (ZLS) compression method includes generating compacted depth information by condensing information of a depth image and a compressed binary representation of the depth image using histogram compaction and decorrelating the compacted depth information to produce bitplane slicing of residuals by spatial prediction. In another example, an apparatus includes imaging circuitry that can capture one or more depth images and processing circuitry that can generate compacted depth information by condensing information of a captured depth image and a compressed binary representation of the captured depth image using histogram compaction; decorrelate the compacted depth information to produce bitplane slicing of residuals by spatial prediction; and generate an output stream based upon the bitplane slicing.

A method of video coding with reduced implementation cost by reusing transform coefficient buffer palette for palette coding is disclosed. If the current prediction mode is an Intra prediction mode or the Inter prediction mode, information related to transform coefficients for prediction residual of the current block resulted from Intra prediction or Inter prediction is stored in the transform coefficient buffer. If the current prediction mode is the palette coding mode, information related to palette data associated with the current block is stored in the transform coefficient buffer. The current block is then encoded or decoded based on the information related to the transform coefficients if the current block is coded in the Intra prediction mode or the Inter prediction mode, or the information related to the palette data stored in the transform coefficient buffer if the current prediction mode is the palette coding mode.

A method of video coding with reduced implementation cost by reusing transform coefficient buffer palette for palette coding is disclosed. If the current prediction mode is an Intra prediction mode or the Inter prediction mode, information related to transform coefficients for prediction residual of the current block resulted from Intra prediction or Inter prediction is stored in the transform coefficient buffer. If the current prediction mode is the palette coding mode, information related to palette data associated with the current block is stored in the transform coefficient buffer. The current block is then encoded or decoded based on the information related to the transform coefficients if the current block is coded in the Intra prediction mode or the Inter prediction mode, or the information related to the palette data stored in the transform coefficient buffer if the current prediction mode is the palette coding mode.

Intra prediction is used in state-of-the-art video coding standards such as AVC. The intra prediction modes are coded into the bitstream. Luma and chroma components could potentially have different prediction modes. For chroma components, there are 5 different modes defined in AVC: vertical, horizontal, DC, diagonal down right, and “same as luma”. Statistics show that the “same as luma” mode is frequent used, but in AVC, this mode is encoded using more bits than other modes during entropy coding, therefore the coding efficiency is decreased. Accordingly, a modified binarization/codeword assignment for chroma intra mode signaling is able to be utilized for high efficiency video coding (HEVC), the next generation video coding standard.

Intra prediction is used in state-of-the-art video coding standards such as AVC. The intra prediction modes are coded into the bitstream. Luma and chroma components could potentially have different prediction modes. For chroma components, there are 5 different modes defined in AVC: vertical, horizontal, DC, diagonal down right, and “same as luma”. Statistics show that the “same as luma” mode is frequent used, but in AVC, this mode is encoded using more bits than other modes during entropy coding, therefore the coding efficiency is decreased. Accordingly, a modified binarization/codeword assignment for chroma intra mode signaling is able to be utilized for high efficiency video coding (HEVC), the next generation video coding standard.

Systems and methods for reducing, with minimal loss, optical sensor data to be conveyed to another system for processing. An eye tracking device, such as a head-mounted display (HMD), includes a sensor and circuitry. The sensor generates image data of an eye. The circuitry receives the image data, and assigns pixels of the image data to a feature region of the eye by comparing pixel values of the pixels to a threshold value. A feature region refers to an eye region of interest for eye tracking, such as a pupil or glint. The circuitry generates encoded image data by apply an encoding algorithm, such as a run-length encoding algorithm or contour encoding algorithm, to the image data for the pixels of the feature region. The circuitry transmits the encoded image data, having a smaller data size than the image data received from the sensor, for gaze contingent content rendering.

Systems and methods for reducing, with minimal loss, optical sensor data to be conveyed to another system for processing. An eye tracking device, such as a head-mounted display (HMD), includes a sensor and circuitry. The sensor generates image data of an eye. The circuitry receives the image data, and assigns pixels of the image data to a feature region of the eye by comparing pixel values of the pixels to a threshold value. A feature region refers to an eye region of interest for eye tracking, such as a pupil or glint. The circuitry generates encoded image data by apply an encoding algorithm, such as a run-length encoding algorithm or contour encoding algorithm, to the image data for the pixels of the feature region. The circuitry transmits the encoded image data, having a smaller data size than the image data received from the sensor, for gaze contingent content rendering.