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Image Enhancementin the Spatial Domain

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Spatial domain processesSpatial domain processes

( , ) ,g x y T f x y

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Point ProcessingPoint Processing

Simplest of image enhancement techniques

Processing based only on intensity of individual pixels

s T z

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Intensity Transformation FunctionIntensity Transformation Function

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Example: NegativeExample: Negative

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Intensity Transformation FunctionIntensity Transformation Function

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Levels of ContrastLevels of Contrast

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Gamma CorrectionGamma Correction

Various devices used for image acquisition and display respond based on power law

Process used to correct power law response phenomena is called gamma correction

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Gamma CurvesGamma Curves

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Gamma Correction: ExampleGamma Correction: Example

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Power-law Transformation forPower-law Transformation forContrast EnhancementContrast Enhancement

May also be used to adjust contrast of an image by either expanding or compression gray levels

, gray-level expansion

, gray-level compression

1

1

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Gray-level expansionGray-level expansion

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Gray-level CompressionGray-level Compression

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Piecewise-Linear Transformation FunctionsPiecewise-Linear Transformation Functions

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Gray-level SlicingGray-level Slicing

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Gray-level slicingGray-level slicingExampleExample

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Bit-plane SlicingBit-plane Slicing

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Bit-plane Slicing: ExampleBit-plane Slicing: Example