06-12-2012, 05:33 PM
Image Enhancement
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Introduction to Image Enhancement
Image:
An image as defined in the “real world” is considered to be a function of two real variables, for example, a(x,y) with a as the amplitude (e.g. brightness) of the image at the real coordinate position (x,y).
1.2 Digital image processing:
Image processing modifies pictures to improve them (enhancement, restoration), extract information (analysis, recognition), and change their structure (composition, image editing).Images can be processed by optical, photographic, and electronic means, but image processing using digital computers is the most common method because digital methods are fast, flexible, and precise.
Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subfield of digital signal processing, digital image processing has many advantages over analog image processing; it allows a much wider range of algorithms to be applied to the input data, and can avoid problems such as the build-up of noise and signal distortion during processing.
The following picture shows what exactly an image processing does:
The last three pictures show red, green and blue color channels of a photograph whereas the first image is a composite.
Work that can be done by Image Processing:
• Geometric transformations such as enlargement, reduction, and rotation.
• Color corrections such as brightness and contrast adjustments, quantization, or
conversion to a different color space.
• Registration (or alignment) of two or more images.
• Combination of two or more images, e.g. into an average, blend, difference, or
image composite.
• Interpolation and recovery of a full image from a RAW image format.
• Segmentation of the image into regions.
• Image editing and Digital retouching.
• Extending dynamic range by combining differently exposed images.
Applications:
Image Processing finds applications in the following areas:
• Photography and Printing
• Satellite Image Processing
• Medical Image Processing
• Face detection, Feature detection, Face identification
• Microscope image processing
1.5 Image enhancement:
The principal objective of enhancement is to process an image so that the result is more suitable than the original image for a specific application. However, image enhancement is one of the most interesting and visually appealing areas of image processing.
The aim of image enhancement is to improve the interpretability or perception of information in images for human viewers, or to provide `better' input for other automated image processing techniques.