readme.m

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% README file for the Image Processing Toolbox.
%
% This file contains information about the MATLAB Image Processing
% Toolbox, version 2.1.  The file consists of two parts.  The part
% above the line discusses the ways that version 2.1 of the toolbox
% differs from version 2.0.  The part below the line describes the
% ways in which the version 2.0 differs from version 1.0.
%
% If you are upgrading to version 2.1 from version 2.0, read just the
% part above the line.  If you are upgrading to version 2.1 from
% version 1.0, read both parts.
%
%
% DIFFERENCES BETWEEN VERSION 2.1 AND VERSION 2.0
%
% This section describes the new features and enhancements in version 2.1
% of the Image Processing Toolbox.
%
% Interactive pixel value display
%   The new function pixval installs in a figure an interactive display
%   of the data values for whatever image pixel the cursor is currently
%   over.  You can also click and drag to display the Euclidean
%   distance between two pixels.
%
% Feature measurement
%   The new function imfeature computes feature measurements, such as the
%   center of mass and the bounding box, for regions in an image.
%
% Inverse Radon transform
%   The new function iradon uses the inverse radon transform to
%   reconstruct images from projection data. In addition, the toolbox
%   has a new function, phantom, that generates test images for use
%   with the Radon and inverse Radon transforms.
%
% Canny edge detector
%   The edge function now supports the Canny edge detection method.
%   This method is better at detecting weak edges and is less sensitive
%   to noise than the other supported edge-detection methods.
%
% Other enhancements
%   - The bwfill function can now automatically detect and fill holes in
%     objects.
%   - The toolbox now supports the YCbCr color space, through two new
%     functions, ycbcr2rgb and rgb2ycbcr.
%   - You can now easily convert images between double precision and
%     uint8 using two new functions, im2double and im2uint8.
%   - You can control whether imshow automatically calls truesize by
%     setting the new toolbox preference 'ImshowTruesize'.
%
%
% ------------------------------------------------------------------
% DIFFERENCES BETWEEN VERSION 2.0 AND VERSION 1.0
%
% Topics include:
%
% - general enhancements
% - new functions
% - enhancements to specific functions
% - compatibility issues
% - bug fixes
%
%
% GENERAL ENHANCEMENTS
%
% This section summarizes general areas of enhancement to the toolbox.  See
% the Image Processing Toolbox User's Guide for more information about these
% enhancements.
%
% Support for 8-bit image data
%   Most of the functions in the toolbox have been rewritten to take
%   advantage of MATLAB's support of unsigned 8-bit integers (uint8 data).
%   You can now read images into MATLAB as uint8 arrays, and process these
%   images with the toolbox functions.  As a result, memory usage for most
%   image-processing operations has been dramatically reduced.
%
% N-dimensional arrays
%   The toolbox takes advantage of another new MATLAB feature, N-dimensional
%   arrays.  For example, an RGB image is now stored in a single
%   three-dimensional array, rather than requiring three separate matrices.
%   In addition, multiframe images no longer require image decks, but can
%   now be stored and processed in four-dimensional arrays.
%
% Speed-ups
%   Several of the toolbox functions have been rewritten to run faster, in
%   some cases substantially so.
%
%
% NEW FUNCTIONS
%
% This section describes the new functions in the Image Processing Toolbox,
% as well as new functions in the MATLAB Toolbox that are useful for
% image-processing applications.
%
% Image file I/O
%   imfinfo    - Return information about image file (MATLAB Toolbox).
%   imread     - Read image file (MATLAB Toolbox).
%   imwrite    - Write image file (MATLAB Toolbox).
%
% Image analysis
%   qtdecomp   - Perform quadtree decomposition.
%   qtgetblk   - Get block values in quadtree decomposition.
%   qtsetblk   - Set block values in quadtree decomposition.
%
% Image enhancement
%   ordfilt2   - Perform 2-D order-statistic filtering.
%
% Linear filtering
%   convmtx2   - Compute 2-D convolution matrix.
%   convn      - Perform N-D convolution (MATLAB Toolbox).
%
% Image transforms
%   dctmtx     - Compute discrete cosine transform matrix.
%   fftn       - Compute N-D fast Fourier transform (MATLAB Toolbox).
%   ifftn      - Compute N-D inverse fast Fourier transform (MATLAB
%   Toolbox).
%
% Binary image operations
%   applylut   - Perform neighborhood operations using lookup tables.
%   bwfill     - Fill background regions in binary image.
%   bwlabel    - Label connected components in binary image.
%   bwselect   - Select objects in binary image.
%   makelut    - Generate lookup table for use with applylut.
%
% Region-based processing
%   roifill    - Smoothly interpolate within arbitrary region.
%
% Toolbox preferences
%   iptgetpref - Get value of Image Processing Toolbox preference.
%   iptsetpref - Set value of Image Processing Toolbox preference.
%
% Demos and sample images
%   There are many new demos and sample images in the toolbox. To see a
%   complete list, type:
%
%     helpwin imdemos
%
%
% ENHANCEMENTS TO SPECIFIC FUNCTIONS
%
% Several functions in the toolbox have been enhanced to provide additional
% capabilities.  This section summarizes these enhancements.
%
%   blkproc - The function you specify no longer needs to return output of
%     the same size as the input.  The output can be any size, including
%     empty.
%
%   bwmorph - You can now specify the number of iterations as Inf, in which
%     case bwmorph repeats the specified operation until the image stops
%     changing.
%
%   dilate, erode - You can now choose between a new frequency-domain
%     algorithm and the spatial-domain algorithm used in version 1.  The
%     frequency-domain algorithm is faster for large structuring elements,
%     but uses more memory.  Also, the spatial-domain algorithm is faster
%     than it was in version 1.
%
%   edge - There are two new methods available, 'log' and 'zerocross'.
%
%   hsv2rgb, ntsc2rgb, rgb2hsv, rgb2ntsc - These functions can now convert
%     images as well as colormaps.
%
%   imhist, medfilt2, roipoly - These functions are considerably faster
%     than in version 1.
%
%   imshow - The imshow function has been enhanced in many ways.  See the
%     User's Guide for information about imshow.
%
%
% COMPATIBILITY ISSUES
%
% In order to take advantage of MATLAB features such as uint8 support and
% N-dimensional arrays, most of the functions in the toolbox have been
% rewritten.  This has introduced some incompatibilities that you should be
% aware of.  This section summarizes these incompatibilities.
%
% Grandfathered functions
%
%   Several functions from version 1 of the toolbox have been
%   "grandfathered."  This means that these functions are no longer
%   supported, but still work in version 2.  These functions have been
%   superseded by new functions in the toolbox or in MATLAB.  We recommend
%   that you do not use the grandfathered functions, and that you rewrite
%   any M-files you have that rely on them.  They will be removed from the
%   toolbox in a future release.
%
%   The function mfilter2 has been renamed roifilt2.  mfilter2 has been
%   grandfathered.
%
%   These toolbox functions are redundant with functions available in
%   MATLAB:
%
%   imslice   - use N-dimensional arrays and MATLAB indexing
%   imzoom    - use zoom instead
%
%   These image file i/o functions from version 1 have been superseded by
%   imread, imwrite, and imfinfo:
%
%   bmpread
%   bmpwrite
%   hdfread
%   hdfpeak
%   hdfwrite
%   pcxread
%   pcxwrite
%   tiffread
%   tiffwrite
%   xwdread
%   xwdwrite
%
%   The gifread and gifwrite functions have been removed from the toolbox
%   due to patent restrictions.
%
% uint8 arrays
%   Many of the functions in the toolbox now return uint8 arrays.  For
%   example, functions that return binary images now return them as uint8
%   arrays.  If you have code that performs mathematical operations on
%   binary images, you will need to modify this code to convert the images
%   to double-precision arrays, because mathematical operations are not
%   supported for uint8 arrays.
%
%   In addition, the conventional data ranges are different for uint8 and
%   double-precision images.  For example, a double-precision intensity
%   image has data in the range [0,1], while a uint8 intensity image has
%   data in the range [0,255].  See the User's Guide for more information
%   about differences between uint8 and double-precision images.
%
% RGB images
%   The toolbox functions that take RGB images as input now accept a single
%   three-dimensional array rather than three two-dimensional matrices.
%   For example:
%
%   imshow(R,G,B) - v1 syntax
%   imshow(RGB)   - v2 syntax
%
%   The R,G,B syntax for these functions is grandfathered.  It still works
%   in version 2, but is no longer supported and will be removed in a
%   future release.
%
% Image decks
%   Multiframe images are now stored as four-dimensional arrays, rather
%   than as image decks.  The functions that work with image decks, such as
%   montage, now accept a 4-D array as input.  The image deck syntaxes have
%   been grandfathered.
%
% Morphological operations
%   In version 1, the dilate and erode functions accepted either a
%   structuring element or a string such as 'thin'.  The string syntax has
%   been grandfathered, because in all cases the same operation is
%   available through the bwmorph function.
%
%   Similarly, in version 1 the bwmorph function accepted either a string or
%   a lookup table.  The lookup table syntax has been grandfathered, and
%   these
%   operations are now provided by the makelut and applylut functions.
%   Also, the syntax in which bwmorph returned a lookup table has been
%   grandfathered.  In some cases, this syntax still works; however, for
%   many operations, a lookup table is no longer used, and this syntax
%   produces a warning.
%
%   In addition, the bwmorph operation 'fatten' has been grandfathered,
%   because it does not work well.
%
% Detecting image type
%   In version 1, some of the toolbox functions could determine the type of
%   an image based on its data range, and process it accordingly.  An image
%   with integer values greater than 1 was always an indexed image.
%
%   In version 2, the image type is more difficult to determine; an image
%   with integer values greater than 1 can be indexed, intensity, or RGB.
%   Therefore, certain functions now require you to specify the image
%   type.  These functions are blkproc, colfilt, im2col, medfilt2, and
%   nlfilter.  For example, to process an indexed image with medfilt2:
%
%   X2 = medfilt2(X1,'indexed')
%
%   If you omit the 'indexed' string, X1 is processed as an intensity
%   image, and the results may not be correct.
%
%   Also, the functions that perform interpolation formerly used a
%   different default method depending on whether the image was indexed or
%   not. These functions (improfile, imrotate, and imresize) now always
%   default
%   to nearest neighbor interpolation, regardless of the image type.
%
% dct2 function
%   This function produces different results than in version 1, because
%   it now uses the unitary form of the transform.
%
% edge function
%   The syntax of the edge function has changed substantially. The 'marr'
%   method has been grandfathered, and has been replaced by two new
%   methods, 'log' and 'zerocross'.  (The 'marr' method will still work,
%   but will produce different results from version 1.)  Also, the
%   directionality factor is now specified with a string rather than a
%   vector, and the order of the arguments has changed.  For information
%   about the new syntax, type "help edge" or see the User's Guide.
%
%
% BUG FIXES
%
% This section summarizes the most important bugs in version 1 of the
% toolbox that have been fixed in version 2.
%
%   bwmorph - The 'thicken', 'skel', and 'thin' operations did not preserve
%     the Euler number.
%
%   corr2 - This function produced incorrect answers for inputs with
%     nonzero means.
%
%   edge - The 'marr' method failed to produce continuous contours and
%     produced double-pixel rather than single-pixel edges; the 'sobel'
%     method was computed incorrectly; and the 'roberts' method failed to
%     find some horizontal and vertical lines.
%
%   imnoise - The noise variance calculation for the noise type 'speckle'
%     was incorrect.
%
%   improfile - This function produced an error if the input had duplicate
%     points; and the distance-along-profile computation was incorrect in
%     some circumstances.
%
%   imrotate - In some cases, if you specified a negative angle, imrotate
%     did not rotate the image.
%
%   radon - This function produced inaccurate results.
%
%   roipoly - This function sometime produced incorrect results, especially
%     if the input polygon had closely-spaced vertices.

%   Copyright 1993-1998 The MathWorks, Inc.  All Rights Reserved.
%   $Revision: 1.8 $  $Date: 1997/11/24 15:33:52 $

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