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A Zero-Value Prediction Technique for Fast DCT Computation. Y. Nishida, K. Inoue, and V. Moshnyaga. Problem. Discrete Cosine Transform (DCT) is a very computationally expensive task. DCT require s a measurable amount of energy and many operations.

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A Zero-Value Prediction Technique for Fast DCT Computation


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Presentation Transcript
problem
Problem
  • Discrete Cosine Transform (DCT) is a very

computationally expensive task.

  • DCT requires a measurable amount of energy

and many operations.

Reducing the number of operations and energy consumption of DCT becomes important.

solution
Solution

A Zero-Value Prediction Technique for

Fast DCT Computation.

When the DCT outputs N zeros, we predict the remaining result is also zero.

Example of N=2

The detected string

of zeros

The predicted values

Starting point of

zero-value prediction

advantage and disadvantage
Advantage and Disadvantage

Advantage

  • Reduces the number of DCT and quantization

operations.

  • Reduces energy consumption.
  • DCT speed increases.

Disadvantage

  • The picture quality deteriorates a little.
operation reduction rate as a function of n dct
Operation reduction rate as a function of N(DCT)

carphone

carphone

foreman

foreman

missa

missa

salesman

salesman

×

×

Operation reduction rate

Operation reduction rate

0.5

0.5

0.4

0.4

0.3

0.3

0.2

0.2

0.1

0.1

0

0

3

3

1

1

2

2

4

4

5

5

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8

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9

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18

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19

20

20

N

N

  • The reduction rate is high when N is small.
slide6

carphone

carphone

foreman

foreman

missa

missa

salesman

salesman

×

×

PSNR as a function of N

70

60

50

PSNR (dB)

40

30

20

10

0

3

1

2

4

5

6

7

8

9

10

11

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13

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18

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20

N

  • The PSNR is low when N is small.
  • When N=9, can reduce the number of DCT operations by 29%.
  • The PSNR decreases by 1.47dB.