Xray Image Preprocessing And Enhancement

Although the imaging techniques expansion based on unusual physical phenomena, such as nuclear magnetic resonance, emission of single photons(-radiation) by radio-pharmaceuticals and photon pairs by electron-positron annihilations and reflection of ultrasonic waves ,X-ray based image acquisition is still daily practice in medicine[1]. Computer based techniques is becoming a more talented approach in medical image analysis Low image quality is the main reason for poor behavior as noisy X-ray images produced many weak, small and discontinuous edges inside, outside, and along the shape boundary.

Image preprocessing and enhancement

Digital image is acquired by using imaging sensors. For image enhancement digital image is needs to be processed to improve its quality and make it suitable for a specific application [2]. The image enhancement operations generally fall into two categories local operations, and global operations. A local operation includes those techniques that modify the value of a pixel based upon the values of its direct neighbors. Global operation, on the other hand, refers to those techniques that modify the value of a pixel by an equal amount regardless of the pixel's location in the image space.

Image preprocessing and enhancement refers to accentuation or sharpening of the image features, such as boundaries, edges or contrast to make graphical display more useful for analysis or display. This includes gray level manipulation, noise reduction, edge sharpening, filtering, interpolation and magnification. There are two categories of image enhancement spatial domain, which is based on the direct manipulation of the pixels in the image matrix, and frequency domain, which is based on the Fourier transform of the image.

The various techniques of image enhancement are based on the above two approaches, either used individually or as combination of the two. Image processing is the way to improve the quality of an image and some unwanted noise can be reduced and desired features enhanced by preprocessing [3]. In image processing mainly dealing the image Filtering and Image Enhancement Before going to edge detection [4] image preprocessing is important one[5].

X-ray image

An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. x-rays, are often used to determine the type and extent of a fracture as well as for detecting pathological changes in the lungs. With the use of radio-opaque contrast media, such as barium, they can also be used to visualize the structure of the stomach and intestines - this can help diagnose ulcers or certain types of colon cancer.

X-ray imaging and its image processing techniques are often adopted in automatic inspection of defects.Typically, digitized X-ray images are corrupted by additive noise. De-noising can improve the visibility of some structures in medical X-ray images, thus improving the performance of computer assisted enhancement algorithms. Images may have different types of noise.

In image enhancement, the goal is to accentuate certain image features for subsequent analysis[6].However, image enhancement algorithms generally amplify noise Therefore, higher de-noising performance is important in obtaining images with high visual quality. There exists different adaptive image enhancement methods, such as adaptive unsharp masking, adaptive neighborhood filtering and enhancement, adaptive contrast enhancement, and various adaptive filtering approaches using directional wavelet transform. Some methods require a priori information about the image.

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