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SITI AISYAH1,* , J. S. MANDEEP1
The DCT works by separating images into parts of differing frequencies. During a step called quantization, where part of compression actually occurs, the less important frequencies are discarded. Only the most important frequencies that remain are used to retrieve the image in the decompression process. It is similar to the discrete Fourier transform where it transforms a signal or image from spatial domain to frequency domain. Wavelet transform on the other hand is a multi-resolution transform that allows a form of time-frequency analysis. It provides a progressive encoding of the image at various scales, which is more flexible. The wavelets comprise a normalized set of orthogonal functions on which the image is projected. The aim of this project is to compare the performance of the DCT and the wavelet transform in image processing. Most images contain some amount of redundancy that can sometimes be removed when the image is stored and replaced when it is reconstructed, but eliminating this redundancy does not lead to high compression. Fortunately, the human eye is not very sensitive to a wide variety of information loss. An image can be changed in many ways that are either not detectable by the human eye or do not contribute to degradation of the image. Compression of an image allows the number of bits to be reduced to represent the coded image which contains a number that is smaller than the original format. This number is variable and it depends on how the image is compressed. Different types of wavelets and different stages of DCT compression ratio have been used to perform the transform of a test image. The results were analyzed with the amount of errors introduced during the compression process..
DCT, JPEG2000, Wavelet, Image processing.
SITI AISYAH, J. S. MANDEEP, Image processing using DCT and wavelet transform, Optoelectronics and Advanced Materials - Rapid Communications, 6, 1-2, January-February 2012, pp.29-35 (2012).
Submitted at: Dec. 15, 2011
Accepted at: Feb. 20, 2012
Optoelectronics and Advanced Materials - Rapid Communications
(2022): 0.5 - 2022 Journal Citation Reports (Clarivate Analytics, 2023)
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