Jul
25
2007

This section is sourced from this site: http://www-ccs.ucsd.edu/matlab/toolbox/images/hrefered.html

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 |