In medical images, noise suppression is a particularly delicate and difficult task. A tradeoff between noise reduction and the preservation of actual image features has to be made in a way that enhances the diagnostically relevant image content. The method of wavelet thresholding has been used extensively for denoising medical images. The idea is to transform the data into the wavelet basis, in which the large coefficients are mainly the signal and the smaller ones represent the noise. By suitably modifying these coefficients, the noise can be removed from the data. In this paper, we evaluate several two-dimensional denoising procedures using medical test images corrupted with additive Gaussian noise. Our results, using the peak-signal-to-noise ratio as a measure of the quality of denoising, show that the NormalShrink method outperforms the other wavelet-based techniques (VisuShrink, BayesShrink). We also demonstrate that garrote shrinkage offers advantages over both hard and soft shrinkage.

Image segmentation is an important process of image analysis. It consists of subdividing an image into its constituent parts and extracting these interesting parts. A large variety of segmentation algorithms have been developed. The evaluation and comparison of these algorithms turns out to be important and even indispensable for correctly using them. This paper presents an objective study of segmentation algorithms using the methods of optimal filtering. This study is distinguished from other studies by its consideration of both evaluation and comparison, treating both image cases (noisy and non-noisy ones). The results of implementation, an evaluation of the advantages and the drawbacks of each one of them, and a study of their immunity towards three types of noise are also presented. All these characteristics make this study a general and effective one for revealing the performance of segmentation algorithms using the methods of optimal filtering.

In the framework of the image compression by transform coding, we studied two transformation techniques, respectively, used in the JPEG and JPEG2000 standards: the discrete cosine transform (DCT) and the wavelets transform (WT). We also studied the influence of different coding techniques on the compression rate.We compare the performances of different wavelets. The set of the techniques that we implemented have been applied on different types of images.We verified the compromise that exists between the compression rate and the quality of the reconstructed image.We noted that when we apply the wavelet transform, we succeeded with best results of those found by the use of the DCT.We note also that the quality of reconstruction is better as we increase the order of the filter associated to the Daubechies wavelets.

The quality control of an analog gamma camera in our nuclear department concerns exclusively the detection head. To evaluate the acquisition system we use a test system composed of an output card and software called ASST. The test consists of transforming the digital data of a scintigraphic image into three analog signals similar to those delivered by the detection head. These signals are introduced into the acquisition system for reconstructing the image. The software ASST allows comparison between the original and the acquired image in order to evaluate the quality of acquisition.

The use of telecommunications and information technologies in the medicine domain evolved these last years breathtakingly. This involves the development of the applications bound to the telemedicine. Seeing the importance of this discipline in the improvement of the care quality and in the reduction of treatment costs, the optimization of medical applications performances remains a necessity. In this work, we propose a new and efficient cryptocompression scheme applied to the telediagnostic sector for a secure and authentic medical image transmission. Since only 15% of discrete cosine transform components are encrypted in our approach, a significant reduction in processing time during the encryption and decryption, without tampering the high compression rate of the compression algorithm, can be performed by the proposed scheme.