Image Processing Toolbox User's Guide Getting Started What Is the Image Processing Toolbox? Configuration Notes Related Products Example 1 -- Some Basic Concepts 1. Read and Display an Image 2. Check How the Image Appears in the Workspace 3. Improve Image Contrast 4. Write the Image to a Disk File 5. Check the Contents of the Newly Written File Example 2 -- Advanced Topics 1. Read and Display an Image 2. Estimate the Value of Background Pixels 3. View the Background Approximation as a Surface 4. Create an Image with a Uniform Background 5. Adjust the Contrast in the Processed Image 6. Create a Binary Version of the Image 7. Determine the Number of Objects in the Image 8. Examine the Label Matrix 9. Display the Label Matrix as a Pseudocolor Indexed Image 10. Measure Object Properties in the Image 11. Compute Statistical Properties of Objects in the Image Getting Help Online Help Image Processing Demos MATLAB Newsgroup Image Credits Examples Introduction Images in MATLAB and the Image Processing Toolbox Image Types in the Toolbox Binary Images Indexed Images Grayscale Images Truecolor Images Converting Between Image Types Color Space Conversions Converting Between Image Classes Losing Information in Conversions Converting Indexed Images Multiframe Image Arrays Reading and Writing Image Data Reading a Graphics Image Writing a Graphics Image Querying a Graphics File Converting Graphics File Formats Working with DICOM Files Reading Image Data from a DICOM File Reading Metadata from a DICOM File Writing Image Data or Metadata to a DICOM File Example: Creating a New Series Image Arithmetic Image Arithmetic Saturation Rules Nesting Calls to Image Arithmetic Functions Coordinate Systems Pixel Coordinates Spatial Coordinates Displaying and Exploring Images Overview Understanding Handle Graphics Object Property Settings Using imshow to Display Images Specifying the Initial Image Magnification Controlling the Appearance of the Figure Using the Image Tool to Explore Images Opening the Image Tool Specifying the Initial Image Magnification Specifying the Colormap Importing Image Data from the Workspace Exporting the Image to the Workspace Closing the Image Tool Printing the Image in the Image Tool Using Image Tool Navigation Aids Overview Navigation Panning the Image Displayed in the Image Tool Zooming In and Out on an Image Specifying the Magnification of the Image Getting Information about the Pixels in an Image Determining the Value of Individual Pixels Getting the Display Range of an Image Viewing Pixel Values with the Pixel Region Tool Getting Information About an Image Adjusting the Contrast and Brightness of an Image Understanding Contrast Adjustment Adjusting Contrast and Brightness Using the Window/Level Tool Autoscaling Viewing Multiple Images Displaying Each Image in a Separate Figure Displaying Multiple Images in the Same Figure Displaying Different Image Types Displaying Indexed Images Displaying Grayscale Images Displaying Binary Images Displaying Truecolor Images Special Display Techniques Adding a Colorbar Displaying All Frames of a Multiframe Image at Once Converting a Multiframe Image to a Movie Texture Mapping Printing Images Printing and Handle Graphics Object Properties Setting Toolbox Display Preferences Toolbox Preferences Retrieving the Values of Toolbox Preferences Setting the Values of Toolbox Preferences Building GUIs with Modular Tools Overview Using Modular Tools Displaying the Target Image Specifying the Target Image Specifying the Parent of a Modular Tool Positioning the Modular Tools in a GUI Example: Building a Pixel Information GUI Adding Navigation Aids to a GUI Making Connections for Interactivity Creating Your Own Modular Tools Spatial Transformations Interpolation Interpolation Methods Interpolation and Image Types Resizing an Image Specifying the Size of the Output Image Specifying the Interpolation Method Using Filters to Prevent Aliasing Rotating an Image Specifying the Size of the Output Image Specifying the Interpolation Method Cropping an Image Performing General 2-D Spatial Transformations Example: Performing a Translation Defining the Transformation Data Creating TFORM Structures Performing the Spatial Transformation Performing N-Dimensional Spatial Transformations Example: Performing Image Registration Step 1: Read in Base and Unregistered Images Step 2: Display the Unregistered Image Step 3: Create a TFORM Structure Step 4: Transform the Unregistered Image Step 5: Overlay Registered Image Over Base Image Step 5: Using XData and YData Input Parameters Step 6: Using XData and YData Output Values Image Registration Registering an Image Point Mapping Example: Registering to a Digital Orthophoto Types of Supported Transformations Selecting Control Points Using the Control Point Selection Tool Starting the Control Point Selection Tool Viewing the Images Specifying Matching Control Point Pairs Saving Control Points Using Correlation to Improve Control Points Linear Filtering and Filter Design Linear Filtering Convolution Correlation Filtering Using imfilter Using Predefined Filter Types Filter Design FIR Filters Frequency Transformation Method Frequency Sampling Method Windowing Method Creating the Desired Frequency Response Matrix Computing the Frequency Response of a Filter Transforms Fourier Transform Definition of Fourier Transform Discrete Fourier Transform Applications of the Fourier Transform Discrete Cosine Transform The DCT Transform Matrix DCT and Image Compression Radon Transform Plotting the Radon Transform Viewing the Radon Transform as an Image Using the Radon Transform to Detect Lines Inverse Radon Transform Example: Reconstructing an Image from Parallel Projection Data Fan-Beam Projection Data Computing Fan-Beam Projection Data Reconstructing an Image from Fan-Beam Projection Data Working with Fan-Beam Projection Data Morphological Operations Dilation and Erosion Understanding Dilation and Erosion Structuring Elements Dilating an Image Eroding an Image Combining Dilation and Erosion Dilation- and Erosion-Based Functions Morphological Reconstruction Marker and Mask Pixel Connectivity Flood-Fill Operations Finding Peaks and Valleys Distance Transform Objects, Regions, and Feature Measurement Connected-Component Labeling Selecting Objects in a Binary Image Finding the Area of the Foreground of a Binary Image Finding the Euler Number of a Binary Image Lookup Table Operations Analyzing and Enhancing Images Getting Information about Pixel Values and Statistics Getting Information About Image Pixels Getting the Intensity Profile of an Image Displaying a Contour Plot of Image Data Creating an Image Histogram Getting Summary Statistics About an Image Computing Properties for Image Regions Analyzing an Image Detecting Edges Tracing Boundaries Detecting Lines Using the Hough Transform Using Quadtree Decomposition Analyzing the Texture of an Image Using Texture Filter Functions Using a Gray-Level Co-Occurrence Matrix (GLCM) Intensity Adjustment Adjusting Intensity Values to a Specified Range Histogram Equalization Contrast-Limited Adaptive Histogram Equalization Decorrelation Stretching Noise Removal Using Linear Filtering Using Median Filtering Using Adaptive Filtering Region-Based Processing Specifying a Region of Interest Selecting a Polygon Other Selection Methods Filtering a Region Example: Filtering a Region in an Image Specifying the Filtering Operation Filling a Region Image Deblurring Understanding Deblurring Causes of Blurring Deblurring Model Using the Deblurring Functions Deblurring with the Wiener Filter Deblurring with a Regularized Filter Deblurring with the Lucy-Richardson Algorithm Deblurring with the Blind Deconvolution Algorithm Creating Your Own Deblurring Functions Avoiding Ringing in Deblurred Images Color Working with Different Screen Bit Depths Determining Screen Bit Depth Choosing a Screen Bit Depth Reducing the Number of Colors in an Image Color Approximation Reducing Colors in an Indexed Image Dithering Converting Color Data Between Color Spaces Converting Between Device-Independent Color Spaces Performing Profile-Based Conversions Converting Between Device-Dependent Color Spaces Neighborhood and Block Operations Block Processing Operations Types of Block Processing Operations Sliding Neighborhood Operations Padding Borders Linear and Nonlinear Filtering Distinct Block Operations Overlap Column Processing Sliding Neighborhoods Distinct Blocks Functions -- Categorical List Image Input, Output, and Display Modular Interactive Tools Spatial Transformation and Registration Image Analysis and Statistics Image Arithmetic Image Enhancement and Restoration Linear Filtering and Transforms Morphological Operations Region-Based, Neighborhood, and Block Processing Colormap and Color Space Functions Miscellaneous Functions Functions -- Alphabetical List Release Notes Image Processing Toolbox 5.0.2 Release Notes New Features New Image Exploration and Enhancement Tool New Modular Interactive Tools New Modular Tool Utility Functions Hough Transform Texture Analysis New ICC Color Profile Export Function New Demos Enhancements and Changes to Existing Features New DICOM Anonymizer Function New Integer Lookup Table Function New Toolbox Utility Functions Updates to the imshow Function Changes to Toolbox Preferences Changes to Other Toolbox Functions Performance Improvements Improved Memory Usage Obsolete and Removed Functions Major Bug Fixes Bug Fixes in Version 5 Bug Fixes in Version 5.0.1 Bug Fixes in Version 5.0.2 Upgrading from an Earlier Release Version 5.0.1 Version 5.0.2 Known Issues General Issues Issues Specific to the Linux Platform Issues Specific to the Macintosh Platform Image Processing Toolbox 4.2 Release Notes New Features Enhanced DICOM support Major Bug Fixes Upgrading from an Earlier Release Image Processing Toolbox 4.1 Release Notes New Features Reading and Writing Data with JPEG Lossless Compression Reading ICC Profiles Embedded in TIFF Files Reading and Writing L*a*b* Color Data Major Bug Fixes applycform Fixes Compiling Spatial Transformation Functions Image Processing Toolbox 4.0 Release Notes New Features New Image Viewer Enhanced Color Space Functions New Image Enhancement Methods Enhanced DICOM Support Fan Beam Projection Transforms Boundary Tracing Functions Unsigned Integer Lookup Tables Optimized Image Arithmetic Functions Performance Improvements Minor Enhancements Changes to Sample Images Included Obsolete Functions Major Bug Fixes Image Processing Toolbox 3.2 Release Notes New Features Writing DICOM Files Representing Binary Images Changes to Existing Functions Major Bug Fixes Upgrading from an Earlier Release Change to Data Type of Output Binary Images Change to Interpretation of Input Images Converting Binary Images to an Integer Data Type Image Processing Toolbox 3.1 Release Notes New Features Morphology Spatial Transformations Image Registration Integer Image Arithmetic Integer Image Filtering Deconvolution/Deblurring Support for DICOM Files Miscellaneous New Functions New Demos Major Bug Fixes Version 3.1 Bug Fixes Image Processing Toolbox 2.2.2 Release Notes New Features New Demo Support For Function Handles Documentation Enhanced Major Bug Fixes imshow Fixes bwlabel Segmentation Violation Eliminated dilate And erode Return Correct Answers freqz2 Fixes fspecial Function's `LoG' Option Improved Display for imcrop, improfile, and roipoly Printable Documentation (PDF) Product Page (Web)