MATLAB FUNCTIONS

Functions by Category

The tables below list all functions in the Image Processing Toolbox by category. The tables include a few functions in MATLAB that are especially useful for image processing, such as imread, imfinfo, and imwrite. 

Image Display
colorbar	Display colorbar. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
getimage	Get image data from axes
image	Create and display image object. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
imagesc	Scale data and display as image. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
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. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)

Image File I/O
dicominfo	Read metadata from a DICOM message
dicomread	Read a DICOM image
imfinfo	Return information about image file. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
imread	Read image file. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
imwrite	Write image file. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)

Spatial Transformations
checkerboard	Create checkerboard image
findbounds	Find output bounds for spatial transformation
fliptform	Flip the input and output roles of a TFORM structure
imcrop	Crop image
imresize	Resize image
imrotate	Rotate image
interp2	2-D data interpolation. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
imtransform	Apply 2-D spatial transformation to image
makeresampler	Create resampling structure
maketform	Create geometric transformation structure
tformarray	Geometric transformation of a multi-dimensional array
tformfwd	Apply forward geometric transformation
tforminv	Apply inverse geometric transformation

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
regionprops	Measure properties of image regions
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 Arithmetic
imabsdiff	Compute absolute difference of two images
imadd	Add two images, or add constant to image
imcomplement	Complement image
imdivide	Divide two images, or divide image by constant.
imlincomb	Compute linear combination of images
immultiply	Multiply two images, or multiply image by constant
imsubtract	Subtract two images, or subtract constant from image

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
stretchlim	Find limits to contrast stretch an image
wiener2	Perform 2-D adaptive noise-removal filtering

Image Registration
cpcorr	Tune control point locations using cross-correlation
cp2tform	Infer geometric transformation from control point pairs
cpselect	Control point selection tool
cpstruct2pairs	Convert CPSTRUCT to valid pairs of control points
normxcorr2	Normalized two-dimensional cross-correlation

Linear Filtering
conv2	Perform 2-D convolution. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
convmtx2	Compute 2-D convolution matrix
convn	Perform N-D convolution. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
filter2	Perform 2-D filtering. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
fspecial	Create predefined filters
imfilter	Multidimensional image filtering

Linear 2-D Filter Design
freqspace	Determine 2-D frequency response spacing. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
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. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
fftn	Compute N-D fast Fourier transform. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
fftshift	Reverse quadrants of output of FFT. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
idct2	Compute 2-D inverse discrete cosine transform
ifft2	Compute 2-D inverse fast Fourier transform. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
ifftn	Compute N-D inverse fast Fourier transform. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
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

Morphological Operations (Intensity and Binary Images)
conndef	Default connectivity array
imbothat	Perform bottom-hat filtering
imclearborder	Suppress light structures connected to image border
imclose	Close image
imdilate	Dilate image
imerode	Erode image
imextendedmax	Extended-maxima transform
imextendedmin	Extended-minima transform
imfill	Fill image regions
imhmax	H-maxima transform
imhmin	H-minima transform
imimposemin	Impose minima
imopen	Open image
imreconstruct	Perform morphological reconstruction
imregionalmax	Regional maxima of image
imregionalmin	Regional minima of image
imtophat	Perform tophat filtering
watershed	Find image watershed regions

Morphological Operations (Binary Images)
applylut	Perform neighborhood operations using lookup tables
bwarea	Area of objects in binary image
bwareaopen	Binary area open; remove small objects
bwdist	Distance transform
bweuler	Euler number of binary image
bwfill	Fill background regions in binary image
bwhitmiss	Binary hit-miss operation
bwlabel	Label connected components in 2-D binary image
bwlabeln	Label connected components in N-D binary image.
bwmorph	Perform morphological operations on binary image
bwpack	Pack binary image
bwperim	Find perimeter of objects in binary image
bwselect	Select objects in binary image
bwulterode	Ultimate erosion
bwunpack	Unpack a packed binary image
imregionalmin	Regional minima of image
imtophat	Perform tophat filtering
makelut	Construct lookup table for use with applylut

Structuring Element (STREL) Creation and Manipulation
getheight	Get the height of a structuring element
getneighbors	Get structuring element neighbor locations and heights
getnhood	Get structuring element neighborhood
getsequence	Extract sequence of decomposed structuring elements
isflat	Return true for flat structuring element
reflect	Reflect structuring element
strel	Create morphological structuring element
translate	Translate structuring element

Deblurring
deconvblind	Restore image using blind deconvolution
deconvlucy	Restore image using accelerated Richardson-Lucy algorithm
deconvreg	Restore image using Regularized filter
deconvwnr	Restore image using Wiener filter
edgetaper	Taper the discontinuities along the image edges
otf2psf	Convert optical transfer function to point-spread function
psf2otf	Convert point-spread function to optical transfer function

Array Operations
circshift	Shift array circularly
padarray	Pad an array

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. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
cmpermute	Rearrange colors in colormap
cmunique	Find unique colormap colors and corresponding image
colormap	Set or get color lookup table. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
imapprox	Approximate indexed image by one with fewer colors
rgbplot	Plot RGB colormap components. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)

Color Space Conversions
hsv2rgb	Convert HSV values to RGB color space. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
ntsc2rgb	Convert NTSC values to RGB color space
rgb2hsv	Convert RGB values to HSV color space. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
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
double	Convert data to double precision. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
gray2ind	Convert intensity image to indexed image
grayslice	Create indexed image from intensity image by thresholding
graythresh	Compute global image threshold using Otsu's method
im2bw	Convert image to binary image by thresholding
im2double	Convert image array to double precision
im2mis	Convert image to Java MemoryImageSource
im2uint16	Convert image array to 16-bit unsigned integers
im2uint8	Convert image array to 8-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
label2rgb	Convert a label matrix to an RGB image
mat2gray	Convert matrix to intensity image
rgb2gray	Convert RGB image or colormap to grayscale
rgb2ind	Convert RGB image to indexed image
uint16	Convert data to unsigned 16-bit integers. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)
uint8	Convert data to unsigned 8-bit integers. (This is a MATLAB function. See the online MATLAB Function Reference for its reference page.)

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