1. A Zero-Value Prediction Technique for Fast DCT Computation Y. Nishida, K. Inoue, and V. Moshnyaga

2. Problem  Discrete Cosine Transform (DCT) is a very computationally expensive task. computationally expensive task.  DCT requires a measurable amount of energy and many operations. and many operations. Reducing the number of operations and energy consumption of DCT becomes important.

3. Solution A Zero-Value Prediction Technique for Fast DCT Computation. 61 9 -29821-301 22-6-4070-2-3 1105-4-340-3 2-10500000 00000000 00000000 00000000 00000000 Example of N=2 The detected string of zeros Starting point of zero-value prediction The predicted values When the DCT outputs N zeros, we predict the remaining result is also zero.

4. Advantage and Disadvantage Advantage  Reduces the number of DCT and quantization operations. operations.  Reduces energy consumption.  DCT speed increases. Disadvantage  The picture quality deteriorates a little.

5.  The reduction rate is high when N is small. 12 3 4567891011121314151617181920 N Operation reduction rate 0.3 0.4 0.2 0.5 0.1 0   ▲ × carphone foremanmissasalesman 12 3 4567891011121314151617181920 N Operation reduction rate 0.3 0.4 0.2 0.5 0.1 0   ▲ × carphone foremanmissasalesman Operation reduction rate as a function of N （ DCT ）

6. PSNR as a function of 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. 0 12 3 4567891011121314151617181920 N PSNR (dB) 10 20 30 40 50 60 70   ▲ × carphone foremanmissasalesman   ▲ × carphone foremanmissasalesman