Jpeg analyzer
Download
1 / 13

Jpeg Analyzer - PowerPoint PPT Presentation


  • 90 Views
  • Uploaded on

Jpeg Analyzer. Ben Applegate CSS497 Advisor: Dr. Munehiro Fukuda. Purpose of Research. Create a JPEG analysis program that will run on the UWB Parallel Computing lab's cluster. Potential uses: Agriculture

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Jpeg Analyzer' - faith


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Jpeg analyzer

Jpeg Analyzer

Ben Applegate CSS497

Advisor: Dr. Munehiro Fukuda


Purpose of research
Purpose of Research

Create a JPEG analysis program that will run on the UWB Parallel Computing lab's cluster.

Potential uses:

  • Agriculture

    Webcam images can be analyzed for fruit that is ready to be harvested. Workers can then save time by only going to areas that have fruit.

  • Parking

    Webcams can be placed in a parking garage, and their images can be used to identify areas with open spaces.

  • Web Search

    Images can be found over the web that are similar to an input image. Images can be analyzed, then stored as keywords to be used in searches.


Agriculture
Agriculture

Sort images according to amount of red, as compared to a baseline photo


What is mass

func1( )

func1( )

func1( )

func1( )

func2( )

func1( )

func2( )

func2( )

func3( )

func2( )

func3( )

What is MASS

Public static void main( String[ ] args ) {

MASS.init( args );

Places space = new Places( handle, “MySpace”, params, xSize, ySize);

Agents agents = new Agents( handle, “MyAgents”, params, space, population );

space.callAll( MySpace.func1, params );

space.exchangeAll( MySpace.func2, neighbors );

agents.exchangeAll( MyAgents.func3 );

agents.manageAll( );

MASS.finish( );

}


Jpeg image format
JPEG image format

Created to store the maximum amount of visual data in the least amount of space

Three strategies -

  • Discrete Cosine Transform

  • Entropy Coding

  • Human Vision


Discrete cosine transfom
Discrete Cosine Transfom

The DCT stores cosine waves reducing them to a set of coefficients

JPEG uses an 8x8 DCT

Stores each visual band as a wave

Image source: Wikipedia


Entropy coding

DCT information is stored using huffman encoding

Values are stored in a zig zag pattern to minimize space

Higher frequencies tend to go to zero, so the zig zag can terminate quickly

Entropy Coding

Image source: Wikipedia


Human vision

The human eye can better detect differences in light and dark than in color.

RGB is converted to YCbCr

Y is the luminance

Cb and Cr are the chrominance values, and can be sub-sampled

RGB

Human Vision

Y

Cb

Cr

Image source: NASA


Chroma subsampling

Averages Cb and Cr values to save space dark than in color.

Common sampling ratios are

2 x 1 : Horizontal

2 x 2 : Horizontal and vertical

Cheap cameras (i.e. webcams) mostly use 2x2

Chroma Subsampling


Jpeg mcu

MCU : Minimum Coded Unit dark than in color.

This is the smallest amount of data that can be coded in a given jpeg.

Size depends on subsampling

2x1 = 16px by 8 px

2x2 = 16px by 16px

JPEG MCU

Image source: NASA


Strategy
Strategy dark than in color.

  • Decode MCUs from huffman values

  • Send individual MCUs to MASS to be decoded in parallel using the Inverse DCT:

         The IDCT (like the DCT) requires 64 calculations per pixel

  • Return pixel arrays

  • Rebuild the pixel arrays into the image

Image source: Wikipedia


Results
Results dark than in color.

As expected, analysis time decreased logarithmically as processes were increased


Future
Future dark than in color.

  • Optimize IDCT

  • Extend functionality to other chroma subsampling ratios

  • Improve fault tolerance

  • Optimize MASS calls by observing network overhead

    • Send multiple MCUs to each node

  • Analyze image data using Munsell color codes

    Web search and apple tree pictures