Segmentation of digital video and images into continuous tone and palettized regions
AssigneeMicrosoft Corporation
InventorSanjeev Mehrotra
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Abstract
For encoding of mixed-content images containing palettized and continuous-tone content, continuous tone content regions in the image are detected and separated. Continuous tone content segmentation classifies pixels as continuous tone content by counting a number of unique pixel values within a pixel neighborhood. Pixels whose count exceeds a threshold are classified as continuous tone content. The technique further scans the image for regions of high continuous tone pixel density. The segmented continuous-tone and palettized content can be encoded separately for efficient compression, and then reassembled at decompression.
Claims31
A computer-implemented method of segmenting continuous tone and palettized content in an input image, the method comprising:
- on a per pixel basis, counting a number of unique colors within a neighborhood of the respective pixel in the image;
- classifying pixels having a high number of unique colors within their neighborhood as continuous tone;
- calculating a density of continuous tone pixels for a plurality of regions in the image;
- identifying regions with a high density of continuous tone pixels as continuous tone regions;
- and
- segmenting the image into the continuous tone regions and non-continuous tone regions.
A computer-implemented method of compressing an image containing continuous tone content, the method comprising:
- on a pixel-by-pixel basis, classifying pixels of the region as being continuous tone or non-continuous tone;
- identifying continuous tone regions containing higher densities of continuous tone pixels;
- compressively encoding the continuous tone regions using a first compression process suited to continuous tone image compression;
- and
- compressively encoding other regions using a second compression process.
A computer-readable medium having a computer program stored thereon executable on a computer for performing a method of segmenting continuous tone content of an image, the computer program comprising:
- computer program instructions for counting, on a per pixel basis, a number of unique colors within a neighborhood of the respective pixel in the image;
- computer program instructions for classifying pixels having a high number of unique colors within their neighborhood as continuous tone;
- computer program instructions for calculating a density of continuous tone pixels for a plurality of regions in the image;
- computer program instructions for identifying regions with a high density of continuous tone pixels as continuous tone regions;
- and
- computer program instructions for segmenting the image into the continuous tone regions and non-continuous tone regions.
A computer system comprising:
- a continuous tone content segmenter operating to process pixels in an input image to detect regions having a high density of pixels having a high number of unique pixel values within the respective pixels' neighborhood;
- a palettized image encoder operating to compressively encode portions of the image other than the detected regions using a palettized image compression process;
- and
- a continuous tone image encoder operating to compressively encode the detected regions using a continuous tone image compression process;
- and
- a multiplexer operating to combine the encoded portions and regions into a compressed output data.
A computer-implemented method of decompressing a compressed data stream representing a mixed-content image with continuous tone and palettized content, the compressed data stream containing a continuous tone segment in which a region have a high density of pixels detected as having a high number of unique pixel values in the respective pixels' neighborhood is encoded using a compression type suitable for continuous tone content, the compressed data stream also containing a separate palettized content segment in which palettized content portion of the image is encoded using a compression type suitable for palettized image content, the method comprising:
- decoding the continuous tone segment to reconstruct the continuous tone content region;
- separately decoding the separate palettized content segment to reconstruct the palettized content portion;
- and
- assembling the continuous tone content region and palettized portion to form an image.
A mixed-content image decoder for decoding a compressed data stream representing a mixed-content image with palettized and continuous tone content, the compressed data stream containing a continuous tone segment in which a region have a high density of pixels detected as having a high number of unique pixel values in the respective pixels' neighborhood is encoded using a compression type suitable for continuous tone content, the compressed data stream also containing a separate palettized content segment in which palettized content portion of the image is encoded using a compression type suitable for palettized image content, the decoder comprising:
- a demultiplexer operating to separate the separately encoded continuous tone and palettized content segments from the compressed data stream;
- a palettized image decoder operating to decode the separate palettized content segment to reconstruct the palettized content portion;
- a continuous tone image decoder operating to decode the continuous tone segment to reconstruct the continuous tone content region;
- and
- an image processor operating to assemble the decoded palettized content portion and the continuous tone content region into an image.
A computer-readable medium having computer-executable instructions stored thereon for decompressing a compressed data stream representing a mixed-content image with palettized and continuous tone content, the compressed data stream containing a continuous tone segment in which a region have a high density of pixels detected as having a high number of unique pixel values in the respective pixels' neighborhood is encoded using a compression type suitable for continuous tone content, the compressed data stream also containing a separate palettized content segment in which palettized content portion of the image is encoded using a compression type suitable for palettized image content, the method comprising:
- decoding the continuous tone segment to reconstruct continuous tone content region;
- separately decoding the separate palettized content segment to reconstruct the palettized content portion;
- and
- assembling the continuous tone content region and palettized content portion into an image.
Dependencies are inferred from the claim text.