Computation Visualization Programming For Use with MATLAB ® User’s Guide Version 2 Image Processing Toolbox How to Contact The MathWorks: 508-647-7000 Phone 508-647-7001 Fax The MathWorks, Inc. Mail 24 Prime Park Way Natick, MA 01760-1500 http://www.mathworks.com Web ftp.mathworks.com Anonymous FTP server comp.soft-sys.matlab Newsgroup support@mathworks.com Technical support suggest@mathworks.com Product enhancement suggestions bugs@mathworks.com Bug reports doc@mathworks.com Documentation error reports subscribe@mathworks.com Subscribing user registration service@mathworks.com Order status, license renewals, passcodes info@mathworks.com Sales, pricing, and general information Image Processing Toolbox User’s Guide  COPYRIGHT 1993 - 1998 by The MathWorks, Inc. All Rights Reserved. The software described in this document is furnished under a license agreement. The software may be used or copied only under the terms of the license agreement. 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MATLAB, S imulink, Stateflow, Handle Graphics, and Real-Time Workshop are registered trademarks, and Target Language Compiler is a trademark of The MathWorks, Inc. Other product or brand names are trademarks or registered trademarks of their respective holders. Printing History: August 1993 First printing Version 1 May 1997 Second printing Version 2 January 1998 Revised for Version 2.1 (Online only) January 1999 Revised for V ersion 2.2 (Release 11) (Online only) Image Credits moon Copyright Michael Myers. Used with permission. cameraman Copyright Massachusetts Institute of Technology. Used with permission. trees Trees with a View, watercolor and ink on paper, copyright Susan Cohen. Used with pe rmission. forest Photograph of Carmanah Ancient Forest, British Columbia, Canada, courtesy of Susan Cohen. circuit Micrograph of 16-bit A/D converter circuit, courtesy of Steve Decker and Shujaat Nadeem, MIT, 199 3. m83 M83 spiral galaxy astronomical image courtesy of Anglo-Australian Observatory, photography by David Malin. alumgrns bacteria blood1 bonemarr circles circlesm debye1 enamel flowers ic ngc4024l ngc4024m ngc4024s rice saturn shot1 testpat1 testpat2 text tire Copyright J. C. Russ, The Image Processing Handbook, Second Edition, 1994, CRC Press, Boca Raton, ISBN 0-8493-2516-1. Used with permission. [...]... you to the fundamentals of image processing using MATLAB and the Image Processing Toolbox It describes the types of images supported, and how MATLAB represents them It also explains the basics of working with image data and coordinate systems 1-2 Images in MATLAB and the Image Processing Toolbox Images in MATLAB and the Image Processing Toolbox The basic data structure in MATLAB is the array, an ordered... 1-2 Images in MATLAB and the Image Processing Toolbox 1-3 Data Types 1-3 Image Types in the Toolbox Indexed Images Intensity Images Binary Images RGB Images Multiframe Image Arrays Summary of Image Types and Numeric Classes 1-4 1-4 1-5 1-6 1-7 1-8 1-10 Working with Image. .. an intensity image, indexed image, or RGB image, based on a luminance threshold ind2gray Create a grayscale intensity image from an indexed image ind2gray Create an RGB image from an indexed image mat2gray Create a grayscale intensity image from data in a matrix, by scaling the data rgb2gray Create a grayscale intensity image from an RGB image rgb2ind Create an indexed image from an RGB image You can... binary image as an indexed image with only two colors A binary image can be stored in an array of class double or uint8 (The toolbox does not support binary images of class uint16.) An array of class uint8 is generally preferable to an array of class double, because a uint8 array uses far 1-6 Image Types in the Toolbox less memory In the Image Processing Toolbox, any function that returns a binary image. .. filter a color image that is stored as an indexed image, you should first convert it to RGB format When you apply the filter to the RGB image, MATLAB filters the intensity values in the image, as is appropriate If you attempt to filter the indexed image, MATLAB simply applies the filter to the indices in the indexed image matrix, and the results may not be meaningful The Image Processing Toolbox provides... supports storing image data in arrays of class uint8 and uint16 The data in these arrays is stored as 8-bit or 16-bit unsigned integers These arrays require one eighth or one fourth as much memory as double arrays 1-3 1 Introduction Image Types in the Toolbox The Image Processing Toolbox supports four basic types of images: • Indexed Images • Intensity Images • Binary Images • RGB Images This section... summarizes these image conversion functions Function Purpose dither Create a binary image from a grayscale intensity image by dithering; create an indexed image from an RGB image by dithering gray2ind Create an indexed image from a grayscale intensity image grayslice Create an indexed image from a grayscale intensity image by thresholding 1-13 1 Introduction Function Purpose im2bw Create a binary image from... the Image Processing Toolbox 1-3 Data Types 1-3 Image Types in the Toolbox 1-4 Indexed Images 1-4 Intensity Images 1-5 Binary Images 1-6 RGB Images 1-7 Multiframe Image Arrays... containing the clown image Writing a Graphics Image When you save an image using imwrite, MATLAB s default behavior is to automatically reduce the bit depth to uint8 Many of the images used in MATLAB are 8-bit, and most graphics file format images do not require double-precision data One exception to MATLAB s rule for saving the image data as uint8 is that PNG and TIFF images may be saved as uint16 Since these... File size in bytes • Image width in pixels 1-12 Working with Image Data • Image height in pixels • Number of bits per pixel • Image type: RGB (truecolor), intensity (grayscale), or indexed See the imfinfo entry in the online MATLAB Function Reference for more information Converting The Image Type of Images For certain operations, it is helpful to convert an image to a different image type For example, . Contents 11 Reference 1 Introduction Overview 1-2 Images in MATLAB and the Image Processing Toolbox 1-3 DataTypes 1-3 Image Types in the Toolbox 1-4 IndexedImages 1-4 IntensityImages 1-5 BinaryImages 1-6 RGBImages 1-7 MultiframeImageArrays. 1-2 Images in MATLAB and the Image Processing Toolbox 1-3 DataTypes 1-3 Image Types in the Toolbox 1-4 IndexedImages 1-4 IntensityImages 1-5 BinaryImages 1-6 RGBImages 1-7 MultiframeImageArrays. the functions in the Image Processing Toolbox, type the following command at the MATLAB prompt: helpwin images Installing the Toolbox To determine if the Image Processing Toolbox is installed