Image Processing Toolbox

Reference Introduction

This chapter provides detailed descriptions of the functions in the Image Processing Toolbox. It begins with a list of functions grouped by subject area and continues with the reference entries in alphabetical order.

The list of functions includes all functions in the Image Processing Toolbox itself, plus a few functions in MATLAB that are especially useful for image processing. All of the functions listed have reference entries, with these exceptions:

The MATLAB functions image, imagesc, and interp2. For information about these functions, see the online MATLAB Function Reference.
The Image Processing Toolbox demo functions and slideshow functions. For information about any of these functions, run the demo or slideshow and click the Info button.


Image Display
`colorbar`	Display colorbar (MATLAB)
`getimage`	Get image data from axes
`image`	Create and display image object (MATLAB)
`imagesc`	Scale data and display as image (MATLAB)
`immovie`	Make movie from multiframe indexed image
`imshow`	Display image
`montage`	Display multiple image frames as rectangular montage
`subimage`	Display multiple images in single figure
`truesize`	Adjust display size of image
`warp`	Display image as texture-mapped surface
`zoom`	Zoom in and out of image or 2-D plot (MATLAB)


Image File I/O
`imfinfo`	Return information about image file (MATLAB)
`imread`	Read image file (MATLAB)
`imwrite`	Write image file (MATLAB)


Geometric Operations
`imcrop`	Crop image
`imresize`	Resize image
`imrotate`	Rotate image
`interp2`	2-D data interpolation (MATLAB)


Pixel Values and Statistics
`corr2`	Compute 2-D correlation coefficient
`imcontour`	Create contour plot of image data
`imfeature`	Compute feature measurements for image regions
`imhist`	Display histogram of image data
`impixel`	Determine pixel color values
`improfile`	Compute pixel-value cross-sections along line segments
`mean2`	Compute mean of matrix elements
`pixval`	Display information about image pixels
`std2`	Compute standard deviation of matrix elements


Image Analysis
`edge`	Find edges in intensity image
`qtdecomp`	Perform quadtree decomposition
`qtgetblk`	Get block values in quadtree decomposition
`qtsetblk`	Set block values in quadtree decomposition


Image Enhancement
`histeq`	Enhance contrast using histogram equalization
`imadjust`	Adjust image intensity values or colormap
`imnoise`	Add noise to an image
`medfilt2`	Perform 2-D median filtering
`ordfilt2`	Perform 2-D order-statistic filtering
`wiener2`	Perform 2-D adaptive noise-removal filtering


Linear Filtering
`conv2`	Perform 2-D convolution (MATLAB)
`convmtx2`	Compute 2-D convolution matrix
`convn`	Perform N-D convolution (MATLAB)
`filter2`	Perform 2-D filtering (MATLAB)
`fspecial`	Create predefined filters


Linear 2-D Filter Design
`freqspace`	Determine 2-D frequency response spacing (MATLAB)
`freqz2`	Compute 2-D frequency response
`fsamp2`	Design 2-D FIR filter using frequency sampling
`ftrans2`	Design 2-D FIR filter using frequency transformation
`fwind1`	Design 2-D FIR filter using 1-D window method
`fwind2`	Design 2-D FIR filter using 2-D window method


Image Transforms
`dct2`	Compute 2-D discrete cosine transform
`dctmtx`	Compute discrete cosine transform matrix
`fft2`	Compute 2-D fast Fourier transform (MATLAB)
`fftn`	Compute N-D fast Fourier transform (MATLAB)
`fftshift`	Reverse quadrants of output of FFT (MATLAB)
`idct2`	Compute 2-D inverse discrete cosine transform
`ifft2`	Compute 2-D inverse fast Fourier transform (MATLAB)
`ifftn`	Compute N-D inverse fast Fourier transform (MATLAB)
`iradon`	Compute inverse Radon transform
`phantom`	Generate a head phantom image
`radon`	Compute Radon transform


Neighborhood and Block Processing
`bestblk`	Choose block size for block processing
`blkproc`	Implement distinct block processing for image
`col2im`	Rearrange matrix columns into blocks
`colfilt`	Perform neighborhood operations using columnwise functions
`im2col`	Rearrange image blocks into columns
`nlfilter`	Perform general sliding-neighborhood operations


Binary Image Operations
`applylut`	Perform neighborhood operations using lookup tables
`bwarea`	Compute area of objects in binary image
`bweuler`	Compute Euler number of binary image
`bwfill`	Fill background regions in binary image
`bwlabel`	Label connected components in binary image
`bwmorph`	Perform morphological operations on binary image
`bwperim`	Determine perimeter of objects in binary image
`bwselect`	Select objects in binary image
`dilate`	Perform dilation on binary image
`erode`	Perform erosion on binary image
`makelut`	Construct lookup table for use with `applylut`


Region-Based Processing
`roicolor`	Select region of interest, based on color
`roifill`	Smoothly interpolate within arbitrary region
`roifilt2`	Filter a region of interest
`roipoly`	Select polygonal region of interest


Colormap Manipulation
`brighten`	Brighten or darken colormap (MATLAB)
`cmpermute`	Rearrange colors in colormap
`cmunique`	Find unique colormap colors and corresponding image
`colormap`	Set or get color lookup table (MATLAB)
`imapprox`	Approximate indexed image by one with fewer colors
`rgbplot`	Plot RGB colormap components (MATLAB)


Color Space Conversions
`hsv2rgb`	Convert HSV values to RGB color space (MATLAB)
`ntsc2rgb`	Convert NTSC values to RGB color space
`rgb2hsv`	Convert RGB values to HSV color space (MATLAB)
`rgb2ntsc`	Convert RGB values to NTSC color space
`rgb2ycbcr`	Convert RGB values to YCbCr color space
`ycbcr2rgb`	Convert YCbCr values to RGB color space


Image Types and Type Conversions
`dither`	Convert image using dithering
`gray2ind`	Convert intensity image to indexed image
`grayslice`	Create indexed image from intensity image by thresholding
`im2bw`	Convert image to binary image by thresholding
`im2double`	Convert image array to double precision
`im2uint8`	Convert image array to 8-bit unsigned integers
`im2uint16`	Convert image array to 16-bit unsigned integers
`ind2gray`	Convert indexed image to intensity image
`ind2rgb`	Convert indexed image to RGB image
`isbw`	Return true for binary image
`isgray`	Return true for intensity image
`isind`	Return true for indexed image
`isrgb`	Return true for RGB image
`mat2gray`	Convert matrix to intensity image
`rgb2gray`	Convert RGB image or colormap to grayscale
`rgb2ind`	Convert RGB image to indexed image


Toolbox Preferences
`iptgetpref`	Get value of Image Processing Toolbox preference
`iptsetpref`	Set value of Image Processing Toolbox preference


Demos
`dctdemo`	2-D DCT image compression demo
`edgedemo`	Edge detection demo
`firdemo`	2-D FIR filtering and filter design demo
`imadjdemo`	Intensity adjustment and histogram equalization demo
`nrfiltdemo`	Noise reduction filtering demo
`qtdemo`	Quadtree decomposition demo
`roidemo`	Region-of-interest processing demo


Slide Shows
`ipss001`	Region labeling of steel grains
`ipss002`	Feature-based logic
`ipss003`	Correction of nonuniform illumination

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