Medical Image Denoising Using Mixed Transforms

يقترح في هذا البحث طريقة تعتمد على خليط من التحويلات Wavelet Transform(WT) و Multiwavelet Transform (MWT) من اجل تقليل التشوه في الصور الطبية . تعتمد الطريقة المقترحة على استخدام WT  و MWT بالتعاقب لتعزيز اداء ازالة التشوه من الصور الطبية. عمليا , يتم في البداية اضافة تشويه لصور الرنين المغناطيسي (MRI) والتصوير المقطعي المحوسب (CT)  من اجل الاختبار. ثم تعالج الصورة المشوهة بواسطة WT  لتنتج اربع تقسيمات للصورة موزعة على اساس التردد ويعالج كل تقسيم بواسطة MWT  قبل مرحلة ازالة التشوه المكثفة او البسيطة. اوضحت النتائج العملية ان نسبة الاشارة الى الضوضاء (PSNR) تحسنت بشكل ملحوظ وتم المحافظة على المعلومات الاساسية للصورة. بالاضافة الى ذلك, فان متوسط نسبة الخطا انخفض تبعا لذلك بالمقارنة مع الطرق الاخرى. In this paper,  a mixed transform method is proposed based on a combination of wavelet transform (WT) and multiwavelet transform (MWT) in order to denoise medical images. The proposed method consists of WT and MWT in cascade form to enhance the denoising performance of image processing. Practically, the first step is to add a noise to Magnetic Resonance Image (MRI) or Computed Tomography (CT) images for the sake of testing. The noisy image is processed by WT to achieve four sub-bands and each sub-band is treated individually using MWT before the soft/hard denoising stage. Simulation results show that a high peak signal to noise ratio (PSNR) is improved significantly and the characteristic features are well preserved by employing mixed transform of WT and MWT due to their capability of separating noise signals from image signals. Moreover, the corresponding mean square error (MSE) is decreased accordingly compared to other available methods

Compression of an ECG Signal Using Mixed Transforms

Electrocardiogram (ECG) is an important physiological signal for cardiac disease diagnosis. With the increasing use of modern electrocardiogram monitoring devices that generate vast amount of data requiring huge storage capacity. In order to decrease storage costs or make ECG signals suitable and ready for transmission through common communication channels, the ECG data volume must be reduced. So an effective data compression method is required. This paper presents an efficient technique for the compression of ECG signals. In this technique, different transforms have been used to compress the ECG signals. At first, a 1-D ECG data was segmented and aligned to a 2-D data array, then 2-D mixed transform was implemented to compress the ECG data in the 2- D form. The compression algorithms were implemented and tested using multiwavelet, wavelet and slantlet transforms to form the proposed method based on mixed transforms. Then vector quantization technique was employed to extract the mixed transform coefficients. Some selected records from MIT/BIH arrhythmia database were tested contrastively and the performance of the proposed methods was analyzed and evaluated using MATLAB package. Simulation results showed that the proposed methods gave a high compression ratio (CR) for the ECG signals comparing with other available methods. For example, the compression of one record (record 100) yielded CR of 24.4 associated with percent root mean square difference (PRD) of 2.56% was achieved