Image Compression using Vector Quantization

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Image Compression using Vector Quantization

• Nopparat Pantsaena
• Manas Sangworasil
• Chinnapat Nantajiwakornchai
• Tanasak Phanprasit

Research Center for Communication and Information
Technology (ReCCIT) King Mongkuts Institute of
Technology Ladkrabang (KMITL) Bangkok, Thailand
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Objective

• This research presents the Splitting solution to
  implement the Codebook, which improves the image
  quality by average Training Vectors and then
  splits the average result to Codebook that has
  minimum distortion.

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Outline

• Introduction
• Codebook Design
• Steps of LBG
• Splitting Codebook design
• Experimental and Result
• Conclusion

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Introduction
Source Image
Training Vector
1 2 3 ..


..
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Introduction
Training Vector
Codebook Design
Codebook Table
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Introduction
New Image (Index Table)
Codebook Table
i1 i5 i39 i10
i45 i45 i200 i12
i54 i256 i96 i78
i256 i54 i5 i9
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Introduction
.(1)
Block diagram of Vector Quantization
Intro
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Codebook Design

• There are two kinds of Codebook
• Random Codebook
• Splitting Codebook

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Comparison between Random and Splitting Codebook
Design

• Splitting has certain loops to find new codebook.
• Splitting faster than Random algorithm.
• Codebooks size define by 2R.
• Random technique will not work if R is not an
  integer. But we can use the Spitting algorithm.

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Codebook Design

• Linde-Buzo-Grays Algorithm (LBG)
• xj(k) xj(1) xj(2) xj(3)xj(k)
• j 1,2,3,,n n number of the image parts
• k vector dimension (k1,2,3,,16)

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Steps of LBG

• Initial the value for Codebook
• Xi(k)(1)(2)(3)(k) i1,2,3,,Nc
• Nc is number of vector in Codebook

Back
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Steps of LBG

• Grouping the Training Vectors

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Steps of LBG

• P((k) ) (Si i1,2,3,,Nc)
• Si is the set of minimum distortion vectors
• xj ? Si if
• Minimum Distortion Values

.(2)
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Steps of LBG

• Average distortion
• The average distortion can be calculated from
  each group, is given by

.(3)
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Steps of LBG

• Stop update the codebook if
• And we can obtain the New Codebook

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Steps of LBG

• Otherwise, the process will continue update in
  the Codebook by average the group in 2nd step
  vectors as

.(4)
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Splitting Codebook design
Split the Codebook to 2 vectors and
START
Divide the image into small blocks
Update Ym M2M
Arranging vector Ymx1,x2,..xn

LGB Algorithm
Set M1 then Ymx1 ,x2 ,..x16 Find centroid of
vector by
No
MNc
Yes
END
Keep Ym
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Splitting Codebook design

• From Training Vector, find the average of
  Training Vectors for setting the Codebook as
  follows
• k1,2,3,,16
  
• n 1,2,3,,16384

.(5)
Back
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Splitting Codebook design

• Split the Codebook to 2 vectors

.(7)
.(6)
j 1,2,3,,Nc

ni 1,2,3,,16
Back
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Splitting Codebook design

• Split the Codebook to 2 vectors

Back
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Experimental and Result

• The value of PSNR is calculated from
• RMSE
• when
• f(i,j) is the gray level of pixel i in the
  original image
• f(i,j) is the gray level of pixel i in the
  decompressed image.
• N is the total number of pixels in the image.

.(8)
.(9)
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Experimental and Result
Figure1. Lena
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Experimental and Result
Figure 2. Milk drop
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Experimental and Result
Figure 3. Mandrill
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Experimental and Result
Figure 4. Girl
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Conclusion

• This paper proposed the implementation of
  Codebook to Vector Quantization image
  compression. From the experiment, the Split
  Codebook can achieve higher image quality than
  Random Codebook at the same bits rate. In another
  words, the proposed algorithm achieves lower bits
  rate at the same image quality

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Thank you for your attention.