Medical Image Enhancement based on Statistical and Image Processing Techniques

DOI : 10.17577/IJERTV10IS050294

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Medical Image Enhancement based on Statistical and Image Processing Techniques

Sidhavi Naidu

Computer Engineering SRIEIT, Goa University

Prajakta Parvatkar

Computer Engineering SRIEIT, Goa University

Ayesha Quadros

Computer Engineering SRIEIT, Goa University

K.M Chaman Kumar

Computer Engineering SRIEIT, Goa University

Arsha Natekar

Computer Engineering SRIEIT, Goa University

Shailendra Aswale

Computer Engineering SRIEIT, Goa University

Abstract:- X-rays are the most used clinical pictures to study the inner structures of the human body. X- rays images consists of issues of low contrast, noise and low intensity. Therefore, the medical image quality enhancement is required. In this paper, a new enhancement procedure is proposed for X-ray images based on statistical and image processing concepts. It is the combination of Gaussian filter, Contrast- stretching transformation, Standard logic, Logarithmic image processing and statistical range. The proposed method will help the doctors and also the patients to identify particular diseases accurately. The proposed method will result in images having improved contrast, reduced noise, etc. In short, the proposed method provides better image quality in less processing time.

Keywords X-Ray, Medical imaging, Image processing, Edge detection, Histogram Equalization, Wavelet Transform, Statistical Range.


Medical images play a very important role in treatment of patients. It depicts various parts and tissues of human body. An enhanced medical image is necessary for doctors to make accurate diagnosis and treatment [13].

Medical imaging means viewing a human body to treat medical conditions or diagnose by using different techniques. Because of progression in clinical procedures, identification of the diseases has become easier. Medical imaging includes techniques like X-Ray, MRI, ultrasound, endoscopy etc. Medical imaging is very important in healthcare world-wide for physicians to diagnose, treat and prevention purpose. Regardless of whether you have encountered a physical issue, are suffering from chronic pain, or are facing another medical condition, medical imaging permits specialists to figure out what is going on inside your body and suggest the appropriate treatment. Without medical imaging both diagnosis and treatment in digital

health can be very hard to accomplish with any degree of precision.

An X-ray is a quick, painless test that produces images of structures inside human body-particularly bones. X-ray beams pass through the body, and they are absorbed in different amounts depending on the density of the material they pass through. The X-ray has been widely used in the biomedical and medical fields since it was born. At present, X-rays has become important basis in the process of medical diagnosis. Medical X-ray image contains a large amount of information, but the details are fuzzy and contrast is low, which makes adverse effects on the doctors judgment. Thus, improving the image contrast and enhancing the details sharpness while suppressing the noises are the key points of this kind of image enhancement [4].

Medical image enhancement intense to improve the perceivability of the image. Image enhancement methods provide benefits like denoising, sharpening edges, increasing brightness, increasing contrast, etc. which helps the doctors and the physicians to observe fine details of the image more carefully. Enhancement methods include contrast adjustment, histogram equalization, edge preserving filters, wavelet-based approaches, deblurring, denoising etc. Medical images are often obtained with low- contrast, low-intensity, noise, blurred, etc. due to limitations in the medical devices. Such images have poor quality and cannot be used for diagnostic purpose. Thus, it is necessary to process the images accurately to produce better-quality images with improved details for better analysis. In the last few years, different methods have been introduced by various researchers to deal with the low- quality images. Numerous search methods are discussed below.

This paper is organized as follows: In Section II, we review relevant work on various medical image

enhancement techniques. Section III contains our proposed method and Section IV has conclusion of the paper.


    The main aim of medical image enhancement techniques is to make internal structures and conditions visible within the patient to the doctors and physicians for proper diagnosis and treatment.


      [3] Here, equalization of the contrast distribution at the boundaries of objects and background of the image is proposed. This provides the increase of contrast enhancement of low-contrast images.

      [9] This paper presents N-CLAHE algorithm which consists of the log-normalization and CLAHE. The result shows that it provided the best image quality when compared with HE, USM and CLAHE.

      [15] This paper presents modied local histogram equalization method. This approach results in a

      clearly visible edge of xture and screw area in the image.

      1. This paper introduces a new form of histogram called gray-level information histogram. This results in increasing contrast of low-contrast images.

      2. In this paper, the proposed algorithm enhanced the X-ray image. The results proved that the proposed algorithm is effective and efficient to enhance the X-ray images.

      [23] In this study, we improved the performance of original anisotropic diffusion by combining with the histogram equalization and weighted K-means clustering. This reduces the noise and also increases the image contrast.

      [31] in this paper, Global enhancement algorithm for medical X-ray image is proposed. The noise in medical X- ray image is removed by using multi- wavelet transform.










      http://vatechrussia. ru/wp- content/uploads/20 16/05/CEPH_Pax-


      Histogram Java programming language

      In automatic mode, it preprocesses low contrast images



      Enhances contrast of low- contrast images




      Java programming language




      Provides good image quality



      Modified local histogram equalization Microsoft Visual Studio, C#, EmguCV,


      After enhancement there is decrease in quality of an image


      Provides clearly visible edges of fixture and screw



      Gray Level Histogram

      Different gray levels of an image are assessed accurately

      Increases contrast of background noise


      Increases the overall contrast



      CLAHE, Fuzzy Set Theory MATLAB

      Can be used in different fields



      Enhance and sharp the image detailing



      Anisotropic diffusion, Histgram Equalization- means clustering


      Causes Gaussian blurring


      Enhances image contrast, reduces noise



      Histogram Equalization, multi- wavelet transform MATLAB

      High degree of noise reduction



      Denoising and enhancement

    2. FILTERS

      [4] In this paper, a new method based on homomorphic filtering was proposed which used TV model as a transfer function. The method resulted in an enhanced image.

      [7] In this paper, experiments on low-quality images were dealt with by the proposed method and other existing methods. The results showed that the edges are preserved and the noise is removed.

      [11] This paper aims to present an iterative algorithm based on Guided Image Filtering for contrast enhancement. This suppresses artifacts and also enhances the contrast.

      1. In this paper an Iterative 2D Kalman filter is used enhancing the medical images. It provides clearer edges, better and clear result of any image those are in this filtering process.

      2. In this paper, a method was proposed that detects edges from X-Ray image based on Gaussian filter and statistical range. The proposed algorithm detects edges, robust to noise, provides better quality image.

      [18] This proposed method is based on histogram equalization and homomorphic filtering. It enhances the low contrast images more efficiently as compared to other methods.

      Table 2: FILTERS










      Guided filter

      Suppresses artifacts



      Reduces noise, preserves edges



      Kalman filter MATLAB

      It is direct and time reliant



      Clears out the edges and provides better and clear result



      Statistical range method, Gaussian filter Scilab 5.5.2

      Removes noise and requires less time



      Removes noise and provides clear edges


      National brain research centre (NBRC), Manesar, public image database

      Homomorphic Filtering, Histogram Equalization, Gamma Correction MATLAB

      Can be used in video processing



      Enhances the low contrast images



      Tv homomorphic filter

      TV model provides better detail enhancement

      Using the TV model may be difficult


      Reduces the uneven brightness in the image


      Images were collected from DDR system without processing

      Fuzzy noise removal method, Homomorphic filtering





      Reduces noise, preserves fine texture and edges


      1. In this paper a model is proposed to enhance image with Haar wavelet transform. Visibility of the enhanced image is better compared to the original image.

      2. The proposed algorithm is based on wavelet homomorphic filtering and CLAHE, can enhance the image brightness, contrast and details and suppress the noise amplification, avoids over- enhancement.

      [17] In this paper, the proposed method for increasing contrast of the X-ray image which is based on CLAHE, morphological processing and is proposed which is based on stationary wavelet

      wavelet transformations results in noise suppression and detail preservation.

      [22] In this paper, a method was proposed using wavelet transform and multiresolution analysis. This provides good quality images and also detects edges with less computation time.

      [28] The proposed method to reduce speckle noise which is based on stationary wavelet transform and fuzzy logic, reduces noise, enhances contrast and preserves edges.

      [30] In this paper, a new medical image illumination enhancement and sharpening technique

      is proposed which is based on stationary wavelet transform. Compared to conventional techniques, this method was superior.











      Wavelet transform, Multiresolution analysis MATLAB

      Requires less processing time



      Detects edges


      Images were collected from Reliance Medical Center, TB gate, Mohakhali, Dhaka, Bangladesh

      Haar wavelet transform, Histogram matching technique MATLAB

      Increase in high frequency components of an image



      Visibility of the image is improved



      Wavelet transform, Improved homomorphic filtering, CLAHE MATLAB

      Avoids over- enhancement



      Improves brightness, contrast and denoising


      Real grayscale X- ray images


      Morphological Processing, Wavelet Packet Decomposition MATLAB

      Enhanced images can be used for 3D reconstruction



      Enhances image and reduces noise



      Stationary Wavelet Transform, Fuzzy logic MATLAB


      Can lead to loss of some information due to decomposition


      denoising, sharpens edges, increases the contrast


      Randomly chosen from a variety of databases

      Stationary Wavelet Transform MATLAB

      Provides better results than

      conventional methods



      Sharpens the image


    1. The proposed method is based on Laplacian, Sobel, Power law transformation. This results in sharpened image and edges were also detected.

    2. The proposed method is the combination of CSL, LIP, SL. This provides pleasant appearance, natural contrast, acceptable brightness, and no visible flaws.

    [10] This paper a method was proposed based on dark channel prior for enhancing the image. This results in increase of contrast and also highlights the details.

    [12] The proposed paper presents a prototype of a new generation of medical image fil digitizer. This improves the quality of overexposed images, improves the readability of images that have lost its quality.

    [21] In this paper, modified Harris corner detector is introduced. This removes Poisson noise from the images.

    1. In this paper, the proposed method use morphological operators for enhancing contrast of images. This method results in improved and clear output result.

    2. The method is based on Stacked Random Forests Feature Fusion. This method helps to detect edges.

    3. Here, a method was proposed using contrast adjustment, image fusion and component attenuation. The proposed method enhances edges and fine details.

    [29] In this paper, we propose an adaptive fractional differential calculus-based technique. This results in clearer edges and richer textures.











    Laplacian, Sobel gradient, power law transformation Object oriented language

    Works very well in different fields

    Any color image activity is not tested


    Sharpens the edges


    https://www.kaggl mooney/chest- xray- pneumonia

    Dark Channel Prior


    Noise amplification


    Increases contrast, highlights features



    Guided filter Canon optical module with a 20 megapixels CMOS sensor

    Quality images are obtained without misrepresentation of structures



    Over-bright images are improved


    https://www.ctisus. com/


    Can be used with simple hardware devices



    Enhances contrast, brightness and denoising



    Improved Harris operator, Median filtering MATLAB




    Removes noise


    ChestX-ray8, NLM (Open-i)

    Top-hat, bottom-hat transform, SE MATLAB


    Time consuming


    Enhances contrast


    Images retrieved through a web image search engine

    Stacked Random Forests Machine Learning Tools

    Capable of combining different image features

    Difficulty in capturing fractures


    Edge detection


    Dataset provided by Japanese Society of Radiological Technology

    Component attenuation, Contrast adjustment, and Image fusion



    Tiny features cannot be recognized


    Enhances edges and fine details


    https://radiopaedia. org/cases/emphyse ma- on-chestx-ray

    Adaptive Fractional Differential Approach JAVA programming language

    Without changing gray level textures can be enhanced

    Smooth areas are neglected


    Enhances Contrast and edges


    The proposed method is the combination of some basic statistical and image processing concepts.


    Step1- An X-Ray image is taken as an input.

    Step2- Applying Gaussian filter for image smoothing. Step3- An Input image is partitioned into 3 x 3 matrix. Step4- We use statistical range. In this step we calculate range of 3×3 matrix.

    Statistical Range= lowest pixel value – highest pixel value. Step5- We will replace the center pixel value of 3 x 3 matrix with pixel value achieved in step-4.

    Step6-Repeat step-3, step-4 and step-5 until we find the statistical range of last 3 x 3 partition of an input image.

    Step7- The edges of the input X-Ray image are detected.

    Next, we aim to enhance the overall contrast on an X-Ray image.

    Step8- We use Contrast-stretching Transformation (CST) method that aims to enhance the local contrast.

    Step9- We use standard logistic (SL) function to enhance global contrast.

    Step10- We combines results of step-8 and step-9 using Logarithmic Image Processing (LIP).

    Step11- We will compute parameters and parameters that are used to control stretching process.

    Step12- We will use Linear Stretching method to reallocate image pixel values to the regular range. Step13- Finally, we will achieve an improved contrast image.

    Flowchart of proposed algorithm


A survey of many image enhancement techniques such as Histogram Equalization, Wavelet Transform, etc. is presented along with their comparison. In this paper, a new method is proposed to enhance X-Ray images. The proposed method is the combination of statistical and image processing concepts. The proposed algorithm provides enhanced contrast and edge detected image. Additionally, our algorithm also removes noise, provides better image quality and enhances features. Simple hardware devices can be used for this method.


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