Types of Image Compression for Medical Imaging

Medical imaging, as we all know, is the process of taking images of various parts of the human body for diagnostic and surgical purposes. Some of the popular medical imaging modalities are X-ray radiography, Magnetic resonance imaging, Medical ultrasound, Computed tomography etc. Since, these images contain clinical data of extreme importance for treatment follow-ups and are acquired at cost of radiation exposure, infrastructure, money and time involved. Thus, once acquired, the medical imaging data should not be disposed off casually, instead it should be retained so that it can be utilized for various medical applications and the chances of repeated testing can be minimized. Also, maintaining electronic health records of patients serves as database for medical research and experimentation. However, growing use of digital imaging techniques has exponentially increased the demands for storage space, handling and transfer of these medical images. These digital image files have large size and thus, require a huge amount of memory space. Moreover, transmitting these files over networks is a time consuming job.

Let us consider the example of a low resolution color image of dimensions 512 x 512 which is to be transmitted over telephone lines. Now, using a 48000 bits/sec modem, the transmission of this single image itself would take approximately 22 minutes which is unacceptable for most applications especially for Telemedicine applications. Hence, the development of techniques for efficient storage and transmission of images has become quite necessary [1].

1.1 Image compression- an overview

A common characteristic of most of the images is that the neighboring pixels are highly correlated and therefore contain superfluous information. I...

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...later in chapter 3 & 4 in greater detail.

1.6.3. Image quality assessment

Image quality assessment is another step in image processing in which statistical parameters are used to measure the quality of the processed image in reference to the raw image or the original image. We shall discuss that later in Chapter 5.

1.6.4. Software tool used

MATLAB was used as a tool for processing of medical images. It is a numerical programming and computing environment which was developed by Math Works. MATLAB makes use of matrices to perform all sorts of mathematical calculations and has a rich functions library. We can also plot functions in 2D, 3D, create Graphic user interfaces and also interface with programs coded in other programming languages such as C, C++, Java and many more.

It has tightly integrated graph-plotting features and a powerful GUI design environment tool.