Image Denoising Using Wavelets: Application in Medical Imaging - Advances in Heuristic Signal Processing and Applications - page 299

Fig. 13.15 Denoising of the Lena image by modeling with a hidden Markov model combined with
a slightly redundant wavelet transform ( d )

timecourse of cerebral activity), electroencephalograpy (EEG), and electrocardio-
graphy (ECG). However, image and signal processing techniques, commonly used
in these domains, remain rudimentary despite the complexity of the signals to be
analyzed (presence of anomalies of outliers, signal mixing, combination of associ-
ated modalities, inverse problems, and so on) and the demands in terms of extracting
relevant information are increasingly greatly, for example, in terms of the size of a
data set, data modeling, image registration and fusion imaging (modalities), as well
taking into account any current major methodological issues in the field.
The challenge, then, is to establish how wavelet-based multiresolution analysis
(decomposition-reconstruction, feature extraction, segmentation, contour detection,
compression, denoising, progressive transmission, and so on) can be combined with
existing classification techniques to meet present and future scientific and techno-
logical challenges.

13.4.1 Medical Imaging Methods and Techniques

Medical imaging includes the following techniques and methodologies:

• Acquisition, restoration, and image processing of the human body,

• Interpretation and exploitation of these images for therapeutic purposes.

The process of formation or generation of these images is based on princi-
ples from physics, such as the absorption of X-rays (radiography, mammogra-
phy, scanner, or tomodensitometry, or computerized tomography), the magnetic
field (spectroscopy and magnetic resonance imagery

and functional magne-
toencephalography), propagation and reflection of ultrasonic waves (echography,
Doppler, elastography, photoacoustics, thermoacoustics, fUltrasound, or functional
brain ultrasound), radioactivity (gammagraphy or scintigraphy or single photon
emission computed tomography-SPECT-or positron emission tomography, PET)

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