2015
DOI: 10.11591/ijece.v5i5.pp1018-1026
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Wavelet and FFT Based Image Denoising Using Non-linear Filters

Abstract: We propose a stationary and discrete wavelet based image denoising scheme and an FFTbased image denoising scheme to remove Gaussian noise. In the first approach, high subbands are added with each other and then soft thresholding is performed. The sum of low subbands is filtered with either piecewise linear (PWL) or Lagrange or spline interpolated PWL filter. In the second approach, FFT is employed on the noisy image and then low frequency and high frequency coefficients are separated with a specified cutoff fr… Show more

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Cited by 19 publications
(13 citation statements)
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“…Therefore, we need to remove the noise components from the document. Since the input document image is a binary image, we do not use common image denoising methods [31,32], such as median filtering [33], mean filtering [34], or fast fourier transform (FFT) methods [35], and so on.…”
Section: Noise Removalmentioning
confidence: 99%
See 1 more Smart Citation
“…Therefore, we need to remove the noise components from the document. Since the input document image is a binary image, we do not use common image denoising methods [31,32], such as median filtering [33], mean filtering [34], or fast fourier transform (FFT) methods [35], and so on.…”
Section: Noise Removalmentioning
confidence: 99%
“…Then, we use dilation operation to connect the Chinese character's upper part and lower part to form a connected region by considering a circular structuring element with radius 1, and the result is shown in Figure 2c. denoising methods [31,32], such as median filtering [33], mean filtering [34], or fast fourier transform (FFT) methods [35], and so on. In this stage, a CC with less than 25 pixels is considered a punctuation mark or noise and will be removed.…”
Section: Morphological Operationmentioning
confidence: 99%
“…FFT (Fast Fourier Transform) is one of methods for transformation of audio signal in time domain into signal in frequency domain, which means that the audio recording process is kept in digital form in the form of audio spectrum wave with frequency base so it is easier in analyzing recorded audio frequency spectrum. On the other hand, this FFT implementation helps in the processing of filtering input signal properly to be frequency signal [11], [12].…”
Section: Fast Fourier Transformmentioning
confidence: 99%
“…In particular, the application of band pass filters, such as high-pass and lowpass filters, may be considered as a most simple and rudimentary denoising method. The Fourier Transform might also be employed for denoising purposes [8]. However, all these mentioned approaches are ineffective when the noise is concentrated in a frequency band similar to that of the useful part of the signal, and this occurs in several real cases.…”
Section: Introductionmentioning
confidence: 99%