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2 What is Digital Image Processing? The term image refers to a two-dimensional light intensity function f(x,y), where x and y denote spatial(plane) coordinates and the value of f at any point (x,y) is proportional to the brightness ( or gray- level) of the image at that point. A digital image is an image f(x,y) that has been discretized both in spatial coordinates and brightness. A digital image can be considered a matrix whose row and column indices identify a point in the image and the corresponding element value identifies the gray level at that point. The elements of such a digital array are called image elements, picture elements, pixels, or pels, with the last two being commonly used abbreviations of “picture elements”. origin

3 Fundamental Steps in Digital Image Processing Methods whose input and output are images. Methods whose inputs may be images but whose outputs are attributes extracted from those images.

4 Image Acquisition: This is the first step in the process. Acquiring a digital image requires an imaging sensor and the capability to digitize the signal produced by the sensor. Generally, this stage involves preprocessing such as scaling. Image Enhancement: The idea behind the enhancement techniques is to bring out detail that is obscured, or simply highlight certain features of interest in an image. It typically deals with techniques for enhancing contrast, removing noise, and isolating regions whose texture indicate a likelihood of alphanumeric information. Image Restoration: This step is an area that also deals with improving the appearance of an image. Restoration techniques are based on mathematical or probabilistic models of image degradation. Compression: It deals with techniques for reducing the storage required to save an image, or the bandwidth required to transmit it. An application of Wavelets is image data compression.

5 Segmentation: It partitions an input image into its constituent parts or objects. Representation: The output of the segmentation stage usually is raw pixel data, constituting either the boundary of a region or all the points in the region itself. In either case, converting the data to a form suitable for computer processing is necessary. The first decision that must be made is whether the data should be represented as a boundary or as a complete region. Boundary representation is appropriate when the focus is on external shape characteristics such as corners and inflections. Regional representation is appropriate when the focus is on internal properties, such as texture or skeletal shape. Description: Choosing a representation is only part of the solution for transforming raw data into a form suitable for subsequent computer processing. A method must also be specified for describing the data so that features of interest are highlighted. Description, also called feature selection, deals with extracting features that result in some quantitative information of interest or features that are basic for differentiating one class of objects from another. Recognition and Interpretation: Recognition is the process that assigns a label to an object based on the information provided by its descriptors. Interpretation involves assigning meaning to an ensemble of recognized objects.

6 Course Content Chapter 1: Introduction Chapter 2: Digital Image Fundamentals Chapter 3: Image Enhancement in the Spatial Domain Chapter 4: Image Enhancement in the Frequency Domain Chapter 9: Morphological Image Processing Chapter 10: Image Segmentation Chapter 11: Representation and Description Chapter 12: Object Recognition (introduction) Chapter 8: Image Compression (introduction) This class is limited on gray level 2-D images.

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11 Acquire Natural Image Enhance the picture Compress for transmission Encode and Transmit over Digital network Transmitted Codes of image DecodedDecompressed Displayed to Create another Signal (visible light of the display) Received by eyes Interpreted in some fashion by our brain From acquisition to interpretation, the initial signal may be transformed, modified, and retransmitted numerous times.

12 Image Processing Better Image

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14 Computer vision, Image Processing, and Computer Graphics often work Together to produce amazing results.

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38 Distorted ImageRestored Image

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