Module 3 - Spatial Filtering, Slides of Digital Image Processing

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Lecture 2. Intensity Transformation

and Spatial Filtering

Spatial Domain vs. Transform Domain

► Spatial domain

image plane itself, directly process the intensity values of

the image plane

► Transform domain

process the transform coefficients, not directly process the

intensity values of the image plane

Spatial Domain Process

Spatial Domain Process

Image Negatives

Example: Image Negatives

Small

lesion

Example: Log Transformations

Power-Law (Gamma) Transformations

Example: Gamma Transformations

Cathode ray tube (CRT) devices have an intensity-to-voltage response that is a power function, with exponents varying from approximately 1.8 to 2.

Example: Gamma Transformations

Piecewise-Linear Transformations

► Contrast Stretching

— Expands the range of intensity levels in an image so that it spans the full intensity range of the recording medium or display device.

► Intensity-level Slicing

— Highlighting a specific range of intensities in an image often is of interest.

Bit-plane Slicing

Bit-plane Slicing