Image compression techniques have been widely used to store and transmit data which requires storage space and high transfer speed. The explosive growth of high-quality photos leads to the requirement of efficient technique to store and exchange these data over the internet. In this paper, we present a comparative study to compare between the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) algorithms in combination with Huffman algorithm; DCT-H and DWT-H. The comparison is based on five factors, Compression Ratio (CR), Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), Structural Similarity Index Measure (SSIM), and compression/decompression time. The experiments are conducted on five BMP gray scale file images. We found out that DWT-H coding is comparable to DCT-H in term of CR, and outperforms DCT-H in terms of MSE, PSNR, and SSIM. The CR average results of the five test images for DCT-H and DWT-H are 2.36 and 3.17 respectively. Moreover, DCT-H has the average results of MSE = 13.19, PSNR = 37.15, and SSIM = 0.76. While, WDT-H has the average results of MSE = 4.54, PSNR = 42.5, and SSIM = 0.85. On the other hand, DCT-H outperforms DWT-H in term of execution time for compression and decompression. DCT-H has average compression time of 0.358s and decompression time 0.122s, while, WDT-H has 2.38s compression time and 2.13s decompression time.
Key words: DCT,
DWT,
Huffman Coding,
Image Compression,
PSNR,
SSIM
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