Image encoding by vector quantization of regions of an image and codebook updates

An apparatus for encoding an image represented by a plurality of blocks of pixels, said apparatus comprising:

• a preprocessor configured to subsample a portion of the plurality of blocks into subsampled blocks to reduce the amount of data that must be encoded to encode the image;
• an encoder configured to receive the subsampled blocks from said preprocessor and non-subsampled blocks, said encoder being further configured to encode the subsampled blocks and the non-subsampled blocks with separate codebooks;
• and
• a rate controller configured to limit the number of subsampled blocks according to a desired bit-rate.

An apparatus for encoding an image, said apparatus comprising:

• means for encoding each of a plurality of regions of an image with a respective one of a first plurality of codebooks;
• means for generating an error value indicating a measure of distortion resulting from encoding at least one of the plurality of regions with one of the first plurality of codebooks;
• means for dividing the at least one of the plurality of regions into subregions based on the error value;
• and
• means for encoding each of the subregions with a respective one of a second plurality of codebooks.

An apparatus for encoding a current image comprising:

• means for using a previous codebook from a previous image to encode said current image as a first encoded image;
• means for decoding said first encoded image to generate a first decoded image;
• means for comparing said current image to said first decoded image to produce an error value;
• means for updating said previous codebook to create a current codebook for said current image if said error value exceeds a threshold, said threshold being based on an error between a second decoded image generated from a previous encoded image and a previous unencoded image;
• and
• means for encoding said current image as a second encoded image using said current codebook if said error value exceeds said threshold.

An apparatus for encoding a current image comprising:

• means for using a previous codebook from a previous image to encode said current image as a first encoded image;
• means for decoding said first encoded image to generate a first decoded image;
• means for comparing said current image to said first decoded image to produce an error value;
• means for updating said previous codebook to create a current codebook for said current image if said error value exceeds a threshold;
• and
• means for encoding said current image as a second encoded image using said current codebook if said error value exceeds said threshold
• wherein said updating means comprises a means for updating specific entries in said previous codebook to generate said current codebook if decoded vectors generated from said first encoded image have a large error in comparison with said current image;
• wherein said updating means further comprises a means for generating a new codebook to be used as said current codebook if said decoded vectors generated from said first encoded image have a large mean squared error in comparison with said current image and said means for updating entries in said previous codebook has already been operative;
• and
• wherein said new codebook generation means is activated if said updating means has been operative for encoding at least N images sequentially.

An apparatus for encoding a current image comprising:

• means for using a previous codebook from a previous image to encode said current image as a first encoded image;
• means for decoding said first encoded image to generate a first decoded image;
• means for comparing said current image to said first decoded image to produce an error value;
• means for updating said previous codebook to create a current codebook for said current image if said error value exceeds a threshold;
• and
• means for encoding said current image as a second encoded image using said current codebook if said error value exceeds said threshold;
• wherein said updating means comprises a means for traversing nodes in a tree representative of vectors for said previous codebook and determining best entries in said previous codebook to use in said current codebook;
• means for creating additional entries in said tree to better represent said current image;
• wherein said means for creating additional entries comprises splitting nodes in said tree to create two new entries for said current codebook;
• and
• wherein said means for splitting nodes in said tree is operative upon determining that said nodes have a greater population of vectors from the current image associated with them than a population threshold.

An apparatus for encoding a current image comprising:

• means for using a previous codebook from a previous image to encode said current image as a first encoded image;
• means for decoding said first encoded image to generate a first decoded image;
• means for comparing said current image to said first decoded image to produce an error value;
• means for updating said previous codebook to create a current codebook for said current image if said error value exceeds a threshold;
• and
• means for encoding said current image as a second encoded image using said current codebook if said error value exceeds said threshold;
• wherein said updating means comprises a means for traversing nodes in a tree representative of vectors for said previous codebook and determining best entries in said previous codebook to use in said current codebook;
• means for creating additional entries in said tree to better represent said current image;
• wherein said means for creating additional entries comprises splitting nodes in said tree to create two new entries for said current codebook;
• and
• wherein said means for splitting nodes in said tree is operative upon determining that said nodes have a greater distortion of vectors than a distortion threshold.

An apparatus for encoding N images comprising:

• means for encoding N images into N encoded images using a first codebook generated from n images, wherein n is greater than or equal to one and n is less than or equal to N;
• means for determining based on an error between one of said N images and a decoded one of said N encoded images that a second codebook should be used by said means for encoding instead of said first codebook;
• means for determining whether a first number of blocks for said N encoded images having an error greater than an average block error is greater than a threshold;
• and
• means for generating a second codebook for encoding an image encoded subsequent to said N images.

An apparatus for encoding N images comprising:

• means for encoding N images into N encoded images using a first codebook generated from n images, wherein n is greater than or equal to one and n is less than or equal to N;
• means for determining based on an error between one of said N images and a decoded one of said N encoded images that a second codebook should be used by said means for encoding instead of said first codebook;
• filtering means for filtering said N images prior to said encoding means encoding said N images;
• and
• rate control means for controlling said filtering means to generate an encoded bitstream at a desired rate.

A method of encoding a sequence of images comprising:

• generating a first codebook based on vectors obtained from an initial image of said sequence of images;
• encoding a subsequent image of said sequence of images into a subsequent encoded image using said first codebook;
• decoding said subsequent encoded image into a subsequent decoded image using said first codebook;
• determining whether a current frame error between said subsequent decoded image and said subsequent image is greater than a previous frame error between a decoded initial image and said initial image;
• and
• if said current frame error is greater than said previous frame error, generating a second codebook based on said subsequent image and encoding said subsequent image using said second codebook.

A method for transmitting an image, the method comprising:

• separating the image into smooth regions and detailed regions based upon a comparison between pixels and neighboring pixels in the image;
• encoding the smooth regions of the image with a first codebook;
• encoding the detailed regions of the image with a second codebook;
• and
• wherein said step of separating the image into smooth regions and detailed regions comprises the step of calculating, for each one of a plurality of blocks of pixels comprised by the image, an error value indicative of distortion that would result if the one of the plurality of pixel blocks was subsampled, the smooth regions being defined by pixel blocks having lower error values than pixel blocks defining the detailed regions.

A method for encoding images, the method comprising the steps of:

• generating a first codebook based on a first input image;
• encoding a second input image with the first codebook to generate a second encoded image;
• decoding said second encoded image to generate a second decoded image;
• determining whether a difference between the second decoded image and the second input image exceeds a threshold;
• updating the first codebook to generate a second codebook if the difference exceeds the threshold;
• and
• wherein said step of determining whether a difference between the second decoded image and the second input image exceeds a threshold comprises the step of determining a threshold based on a difference between a previous input image and a previous decoded image.

A method for encoding images, the method comprising the steps of:

• generating a first codebook based on a first input image;
• encoding a second input image with the first codebook to generate a second encoded image;
• decoding said second encoded image to generate a second decoded image;
• determining whether a difference between the second decoded image and the second input image exceeds a threshold;
• updating the first codebook to generate a second codebook if the difference exceeds the threshold;
• and
• wherein said step of updating the first codebook to generate a second codebook comprises the step of traversing nodes in a tree to locate a terminal node of the tree having a larger distortion measure than other terminal nodes of the tree.

An apparatus for encoding an image comprising:

• a preprocessor configured to receive the image and to indicate whether a difference between a first region of the image and a second region of the image exceeds a threshold;
• a vector quantizer coupled to said preprocessor and receiving therefrom the first region, the second region and an indication whether the difference exceeds a threshold, said vector quantizer being configured to encode the first region of the image with a first codebook into a first data sequence and, if the difference exceeds the threshold, to encode the second region with a second codebook into a second data sequence;
• a packer coupled to said vector quantizer and receiving the first data sequence and, if the difference exceeds a threshold, the second data sequence therefrom, said packer being configured to generate a datastream containing the first data sequence and, if the difference exceeds the threshold, the second data sequence;
• and
• said packer being further configured to place information in the datastream indicating that the first data sequence is encoded with the first codebook and, if the difference exceeds the threshold, that the second data sequence is encoded with the second codebook.

A method for encoding an image represented by a plurality of blocks of pixels, said method comprising:

• subsampling a portion of the plurality of blocks into subsampled blocks to reduce the amount of data that must be encoded to encode the image;
• encoding the subsampled blocks with a first codebook;
• encoding non-subsampled blocks with a second codebook;
• and
• wherein said step of subsampling a portion of the plurality of blocks includes the step of selecting the portion of the plurality of blocks to subsample by calculating values indicative of distortion expected from subsampling the plurality of blocks.

A method for encoding an image, said method comprising:

• encoding each of a plurality of regions of an image with a respective one of a first plurality of codebooks;
• dividing at least one of the plurality of regions into subregions based on an error value associated with encoding the at least one of the plurality of regions;
• and
• encoding each of the subregions with a respective one of a second plurality of codebooks.