|
|
|
Digital Image Processing
|
Data Compression using Vector Quantization and Huffman Coding for Satellite Imagery
4) Experiment result
The two days, 246 x 256 pixels, Landsat MOS-I MESSR imageries were used for this experiment.The block diagram of this experiment is shown in fig. 3. The 256 codevectors in the codebook were generated by using LBG algorithm. The training sequence was the sequence of 4 x 4 subblocks of the first day imagery (Fig.4). A vector quantization and Huffman coding were applied to the first day imagery. The result of decoded imagery is shown in Fig. 5. The the same processing and codebook were applied to the second day imagery (Fig.6). The result of decoded imagery is shown in Fig. 7.
Figure 3: Block diagram of the experiment
Figure 4: Landsat MOS-I MESSR imagery on the first day (8 bpp)
Figure 5: Decoded imagery (MSE=89.43, Rate=0.5 bpp)
Figure 6: Landsat MOS-I MESSR imagery on the second day (8 bpp)
5) Conclusion
The compressed image using vector quntization and Huffman coding in Fig. 5 has mean square error (MSE)= 89.43 with rate = 0.5 bits per pixels (bpp). Another one in Fig. 7 has MSE = 130.66 wiyth rate= 0.5 bpp. These images can be detected the change of cloud in two days. This is an example of change detection task. Because of the distortion of this technique, the detection should be used with big regions of an imagery such as forest, big river, cloud etc. The height compression rate of this technique is a benefit. Hence, the small organization can easily and economically perform this task by only using a microcomputer.
Figure 7: Decoded imagery (MSE=130.66, Rate=0.5 bpp)
Reference
-
R.C. Gonzales and R.E. Woods, "Digital Image Processing, Addison-Wesley Publsishing Company, Inc., 1992.
- M. Rabbani and P. W. Jones, "Digital Image Compression Techniques, "SPIE Optical Engineering Press, 1991.
- N.M. Nasrabadi and R.A. King. "Image coding using vvector quantization: A Review, "IEEE Trans. Common., vol. COM-36, pp. 957-971, Aug 1980.
- Y. Linde, A. Buzo, and R.M. Gray, "An algorithm for vector quantizer design," IEEE Trans. Commun., vol COM-28 pp. 84-95, Jan 1980.
|
|
|
|
|
|
|
