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IMAGE ENHANCEMENT IN SPATIAL AND FREQUENCY DOMAIN

Under guidance of:-Presented by:-Avadhesh kumarKuldeep kr. SinghManoj kr. YadavRahul kr. shuklaEr.Sanjeev kr. gupta

INTRODUCTION Unfortunately, there is no general theory for determining what is `good' image enhancement. Image enhancement techniques are used as pre-processing tools for other image processing Techniques. Quantitative measures can determine which techniques are most appropriate.. The aim of image enhancement is to improve the interpretability or perception of information in images for human viewers, IMAGEImage is defined as a two dimensional function f(x, y), where x and y are spatial coordinates, that bears information, which can be generated in any form such as visual, x-ray and so on.It can be defined as a 2-d representation of a 3-d world.OR

Image Types Monochrome images ( binary image) Grey scale images Colour images Half-toned imageHUMAN VISUAL SYSTEMIn many image processing applications, the objective is to help a human observer perceive the visual information in an image. The human visual system consists mainly of the eye (image sensor or camera), optic nerve (transmission path), and brain (image information processing unit or computer).

Image enhancementImage enhancement is basically improving the interpretability or perception of information in images for human viewers and providing `better' input .

The principal objective of image enhancement is to modify attributes of an image to make it more suitable for a given task and a specific observer. Types of image enhancement Spatial Domain Methods Temporal Frequency Domain (Spectral) Methods

Spatial domain The term spatial domain refers to the aggregate of pixels composing an image. These methods are procedures that operate directly on these pixels.

Here f(x,y) is the original image and T is the transformation applied to get a new modified image g(x,y).The pixel values are manipulated to achieve desired enhancement. Point processingDigital negative Bit plane slicingContrast stretching

Histogram Neighborhood processing

TemporalImage DeblurringRestoration

10Enhanced image.

Bit plane slicing..Deblurring..Digital negative

Frequency domain Frequency domain methods, the image is first transferred in to frequency domain. The operations are performed on the Fourier transform of the image .

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The frequency domain refers to the plane of the two dimensional discrete Fourier transform of an image.

The purpose of the Fourier transform is to represent a image as a linear combination of sinusoidal signals of various frequencies.

The one-dimensional Fourier transform and its inverse Fourier transform (continuous case)

Inverse Fourier transform:

The two-dimensional Fourier transform and its inverse

Fourier transform (continuous case)Inverse Fourier transform:

Spectral domain Techniquesare based on modifying the spectral transform of an image . Transform the image to its frequency representation. Perform image enhancement. Compute inverse transform back to the spatial domain.

Spatial versus Frequency domain

Manipulating or changing an image representing an object in space to enhance the image for a given application.Techniques are based on direct manipulation of pixels in an image used for filtering basics, smoothing filters, sharpening filters.

MATLAB offers a high performance language for expressing problems and their solutions both mathematically and visually. Typical uses include: Numeric computation and algorithm development. Symbolic computation (with the built-in Symbolic Math- functions). Modeling, simulation and prototyping. Data analysis and signal processing. Engineering graphics and scientific visualization.Tools of enhancement

Getting Started

Command-WindowWorkspace & DirectoryCommand- Historyclear all: clears workspace of all variables close all : closes all the figure windows plot (x, y) : plots vector y versus x % : used for Comments Help : when used with command gives its syntaxBasic Mat lab CommandsMore CommandsX label( ) : Allows you to label x-axisY label( ) : Allows you to label y-axisTitle ( ) : Allows you to give title for plot subplot() : Allows you to create multiple plots in the same window

Examples Working with an ImageShow the image- imshow(x);

See alsoimage(x);

Save the image as a 'TIFF' file- imwrite(x, 'rect.tiff', 'TIFF');

Contd.....Read an image from a 'TIFF' filex = imread('rect.tiff');

MATLAB supports other common file formats:-- BMP(Bitmap)- GIF (Graphics Interchange Format)- JPEG (joint photographic expert group)PNG (Portable Networks Graphic)TIFF(Tagged Image File Format) 47 48 48 50 34 24 49 52 12 3 4 8 58 51 48 44 44 40 43 47 48 47 54 30 16 38 40 0 0 11 12 62 53 48 43 41 39 42 38 38 34 29 17 27 53 36 0 4 14 11 59 50 50 43 39 38 44 25 22 23 24 22 37 57 38 2 3 1 13 59 50 50 43 39 38 44 25 20 20 40 39 46 56 32 5 10 2 18 60 50 50 43 41 39 44 41 39 38 56 50 50 53 27 3 12 5 22 61 49 48 42 41 40 44 49 53 55 48 47 49 50 20 2 11 0 24 59 45 48 41 43 40 41 42 47 48 44 48 44 36 7 4 20 4 28 59 45 49 42 44 41 41 38 40 42 50 55 46 32 1 5 27 10 33 61 43 47 42 44 42 40 39 45 51 51 57 53 40 6 7 21 1 35 61 42 46 40 43 41 39 44 50 43 47 41 54 28 0 2 26 2 46 46 48 50 46 43 45 44 43 44 44 47 43 53 25 0 4 24 1 46 48 47 49 47 43 45 44 .cont

x = imread(' C:\bada backup\ 3d_digital_art.jpg);Operation on image using MATLABImage Enhancement applicationClarifying the compressed image which is used in transmission.In medical fieldX-Ray image.Ultrasound image.MRIMilitary purpose.Satellite communication.

REFRENCES Anil K. Jain, Fundamentals of Digital Image Processing. Englewood Cliffs, NJ: Prentice Hall, 1989. R. C. Gonzalez, Richard E. Woods, Digital Image processing, Addision-Wesely, 2003 Raman Maini and Himanshu Aggarwal JOURNAL OF COMPUTING, VOLUME 2, ISSUE 3, MARCH 2010, ISSN 2151-9617HTTPS://SITES.GOOGLE.COM/SITE/JOURNALOFCOMPUTING/ Comparison Between Different Techniques of Image Enhancement Komal Vij, Yaduvir Singh, International Journal of VLSI and Signal Processing Applications, Vol. 1, Issue 2 , May 2011,(112-117) ,ISSN 2231-3133 MATLAB help, version R2008b.which is provided by our sir. www.wikipedia.com. Dr. Muna F. Al-Samaraie A New Enhancement Approach for Enhancing Image of Digital Cameras by Changing the Contrast International Journal of Advanced Science and Technology Vol. 32, July, 2011 Thank you