Lev Weisfeiler

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Streaming and JPEG2000 Compression for use in
Uncompressed Image Archives

• Lev Weisfeiler
• Aware, Inc.

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Archives of Uncompressed Images

• Data stored uncompressed in PACS
• 2000x2500 CR
• Total Image size 10MB
• 512x512 CT
• Total Image size 0.5 MB
• Great for fast networks since no time spent on
  decoding
• Lossless data quality

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Viewing Images over Slower Networks

• User connecting over slower link may prefer
  compressed data, to minimize time to display of
  full fidelity images
• Total time to display compression time on
  server transmission time decompression time
  on client

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Streaming of Compressed Data

• The total time can be reduced if any of these
  processes can be done in parallel
• Streaming decompression and transmission can be
  interleaved
• data is decompressed and displayed progressively,
  as it is received, without waiting for full image
  data
• Compression and transmission can be interleaved
  as well

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JPEG Streaming

• JPEG encodes data in blocks of 8x8 pixels
• Blocks can be  transmitted as they are encoded,
  without waiting for the rest of the data.  
• Precludes the use of the progressive mode of JPEG
• In progressive mode, the DC terms from each block
  are grouped at the front
• Image can be progressively decoded in 8 row
  chunks, essentially appearing line-by-line from
  top to bottom.
• A significant proportion of the image data is
  necessary for a meaningful first view

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JPEG2000 Progressive Encoding

• Progressive Encoding By Quality
• Image is processed by the wavelet transform
• First quality layer is produced by encoding some
  of the wavelet transform data the layer is
  transmitted in a tile part
• tile part is a JPEG2000 codestream unit
• Process repeated for production of next layer
• Progressive Encoding By Resolution
• Image is processed by the wavelet transform
• The lowest resolution data is encoded and
  transmitted in a tile part
• Process repeated for production of next
  resolution data

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JPEG2000 Progressive Encoding

• Progressive Encoding By Color Channel
• First color channel is processed by the wavelet
  transform, fully encoded, and transmitted in a
  tile part
• Process repeated for production next channel
• Progressive Encoding By Spatial Region
• In a tiled image, each tile can be processed and
  transmitted independently
• In an untiled image, precincts are defined for
  the image and are encoded in their proper order,
  with each one being transmitted once it is fully
  encoded
• Precincts are a spatial division of the wavelet
  transform data

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CR Example

• Network DSL 2Mb/sec, 50 utilization, 10
  overhead
• 2500x2048 CR   10MB Uncompressed
• Transmit time 90 seconds
• Total time to display 90 seconds
• 2500x2048 CR  Losslessly Compressed (4MB)
• Compression1.77 sec
• Decompression 1.44 sec
• Transmit time 35 seconds
• Total Time to display 39 seconds

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CR Example

• 2500x2048 CR  Losslessly Compressed with 3
  Quality Layers
• Thumbnail 70KB
• Visually lossless (201) 540KB
• Lossless 3.4 MB
• Progressive Encoding Time
• Layer 1 0.42 sec
• Layer 2 0.41 sec
• Layer 3 1.08 sec
• Decompression Time
• Layer 1 only 0.14 sec
• Layer 1 and 2 0.35 sec
• All three layers 1.45 sec
• Time to View
• Layer 1 (0.42 sec 0.6 sec 0.14 sec) 1.2
  seconds
• Layer 1 and 2  (0.41 sec 5 sec 0.35 sec) 6
  seconds
• All three layers (1.08 sec 30 sec 1.45 sec)
  33 seconds

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CT Example

• Network DSL 2Mb/sec, 50 utilization, 10
  overhead
• 512x512 CT   500 KB Uncompressed
• Transmit time 4.5 seconds
• Total time to display 4.5 seconds
• 512x512 CT Lossless Compressed 1 layer 130 KB
• Compression 0.13 sec
• Decompression 0.10 sec
• Transmit time 1.1 seconds
• Total Time to display 1.33 seconds

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CT Example

• 512x512 CT  Lossless Compressed 3 Layers
• Thumbnail 10 KB
• Visually lossless (251) 20 KB
• Lossless 130 KB
• Compression
• Layer 1 0.08 sec (encoding x-form time)
• Layer 2 0.02 sec (encoding only)
• Layer 3 0.03 sec (encoding only)
• Decompression
• Layer 1     0.05 sec
• Layer 12   0.06 sec
• Layer 123 0.10 sec
• Time to View
• Layer 1 (0.08 sec 0.09 sec 0.05 sec)
  0.22 seconds
• Layer 12  (0.02 sec 0.18 sec 0.06 sec)
  0.26 seconds
• Layer 123 (0.03 sec 1.17 sec 0.10 sec)
  1.3 seconds

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Adaptable Process

• JPEG2000 encoding progressions can be mixed
• E.g. First resolution and then quality
  progression orders would have the lowest
  resolution data progressively encoded by quality
  and transmitted, followed by the next resolution
• Granularity of the interleaving of the
  compression process and the transmission process
  can be adapted for
• time to first image display
• time to full image display.
• Optimized based on
• application needs
• relative loads on the processor
• network speed