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Function List:

C++ API

image

The Octave-forge Image package provides functions for processing images. The package also provides functions for feature extraction, image statistics, spatial and geometric transformations, morphological operations, linear filtering, and much more.

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Analysis and Statistics

edge
Detect edges in the given image using various methods.
fftconv2
Convolve 2 dimensional signals using the FFT.
corr2
Compute correlation coefficients of images.
mean2
Compute the mean value of the 2D image I.
std2
Returns the standard deviation for a 2d real type matrix.
entropy
Computes the entropy of an image.
entropyfilt
Computes the local entropy in a neighbourhood around each pixel in an image.
qtdecomp
Performs quadtree decomposition.
qtgetblk
Obtain block values from a quadtree decomposition.
qtsetblk
Set block values in a quadtree decomposition.
graycomatrix
Calculates the gray-level co-occurrence matrix P of a gray-level image IM.
houghtf
Perform the Hough transform for lines or circles.
hough_line
Calculate the straight line Hough transform of a binary image I.
hough_circle
Perform the Hough transform for circles with radius R on the black-and-white image BW.
imgradient
Compute the gradient magnitude and direction in degrees for an image.
imgradientxy
Compute the x and y gradients of an image using various methods.
imhist
Produce histogram counts of image I.
immaximas
Finds local spatial maximas of the given image.
normxcorr2
Compute the normalized 2D cross-correlation.
rangefilt
Computes the local intensity range in a neighbourhood around each pixel in an image.
regionprops
Compute object properties in a binary image.
stdfilt
Computes the local standard deviation in a neighbourhood around each pixel in an image.

Arithmetics

imabsdiff
Return absolute difference of image or constant to an image.
imadd
Add image or constant to an image.
imcomplement
Compute image complement or negative.
imdivide
Divide image by another image or constant.
imlincomb
Combine images linearly.
immultiply
Multiply image by another image or constant.
imsubtract
Subtract image or constant to an image.

Black and white image functions

applylut
Uses lookup tables to perform a neighbour operation on binary images.
bwarea
Estimate total area of objects on the image BW.
bwborder
Finds the borders of foreground objects in a binary image.
bwboundaries
Trace the boundaries of the objects in a binary image.
bwconncomp
Find connected objects.
bwdist
Compute distance transform in binary image.
bweuler
Calculate the Euler number of a binary image.
bwfill
Perform a flood-fill operation on the binary image BW1.
bwhitmiss
Perform the binary hit-miss operation.
bwlabel
Label binary 2 dimensional image.
bwlabeln
Label foreground objects in the n-dimensional binary image BW.
bwmorph
Perform morphological operation on binary image.
bwperim
Find perimeter of objects in binary images.
bwselect
Select connected regions in a binary image.
fchcode
Determine the Freeman chain code for a boundary.
labelmatrix
Create labelled matrix from bwconncomp structure.
makelut
Create a lookup table which can be used by applylut.

Colour maps and Colour controls

colorgradient
Define a colour map which smoothly traverses the given colors.
rgb2ycbcr
Convert RGB values to YCbCr.
wavelength2rgb
Convert wavelength in nm into an RGB value set.
ycbcr2rgb
Convert YCbCr color space to RGB.

Display

montage
Create montage from multiple images.

Enhancement and Restoration

histeq
Equalize histogram of grayscale image.
imadjust
Adjust image or colormap values to a specified range.
imnoise
Add noise to image.
imsmooth
Smooth the given image using several different algorithms.
medfilt2
Two dimensional median filtering.
ordfilt2
Two dimensional ordered filtering.
ordfiltn
N dimensional ordered filtering.
stretchlim
Finds limits to contrast stretch an image

Filtering and Transforms

findbounds
Estimate bounds for spatial transformation.
fspecial
Create spatial filters for image processing.
imfilter
Computes the linear filtering of the image I and the filter F.
imtransform
Transform image.
intlut
Convert matrix from look up table (LUT).
iradon
Performs filtered back-projection on the projections in PROJ to reconstruct an approximation of the original image.
nonmax_supress
Performs non-maximum supression on the given edge data.
radon
Calculates the 2D-Radon transform of the matrix I at angles given in THETA.
rho_filter
Filters the parallel ray projections in the columns of PROJ, according to the filter type chosen by TYPE.
uintlut
Computes matrix B by using A as an index to lookup table LUT.

Morhophological Operations

bwareaopen
Perform area opening.
conndef
Create connectivity array.
imbothat
Perform morphological bottom hat filtering.
imclose
Perform morphological closing.
imdilate
Perform morphological dilation.
imerode
Perform morphological erosion.
imopen
Perform morphological opening.
imtophat
Perform morphological top hat filtering.
mmgradm
Perform morphological gradient.
@strel/getheight
Return the heights of a non-flat structuring element.
@strel/getneighbors
Get neighbors relative position and height.
@strel/getnhood
Return the neighborhood of structuring element SE.
@strel/getsequence
Decompose structuring element.
@strel/isflat
Say if a structuring element object is flat or not.
@strel/reflect
Reflect structuring element of strel object.
@strel/strel
Create a strel (structuring element) object for morphology operations.
@strel/translate
Generate a new structuring element, which is SE translated in rows and columns as expressed in the offset 2-dimensional array V.

Read/write

analyze75info
Read header of an Analyze 7.5 file.
analyze75read
Read image data of an Analyze 7.5 file.
analyze75write
Write image data to an Analyze 7.5 file.
readexif
Read EXIF information from JPEG image data.
tiff_tag_read
Read value of TAGs from TIFF files.

Region-based and block processing

bestblk
Calculate block best size for block processing.
blockproc
Processes image in blocks using user-supplied function.
col2im
Rearrange block columns back into matrix.
colfilt
Apply function to matrix blocks
im2col
Rearrange blocks from matrix into columns.
impixel
Get pixel values.
nlfilter
Process matrix in sliding blocks with user-supplied function.
poly2mask
Convert a polygon to a region mask.
roicolor
Select a Region Of Interest of an image based on color.

Spatial transformations

cp2tform
Returns a transformation structure T (see "help maketform" for the form of the structure) that can be further used to transform coordinates from one space (here denoted "RW" for "real world") to anoth
imcrop
Crop image.
impad
Pad (augment) a matrix for application of image processing algorithms.
imperspectivewarp
Applies the spatial perspective homogeneous transformation P to the image IM.
imremap
Applies any geometric transformation to the image IM.
imresize
Resize image with interpolation
imrotate
Rotate image about its center.
imrotate_Fourier
Rotation of a 2D matrix.
imshear
Applies a shear to the image M.
imtranslate
Translate a 2D image by (x,y) using Fourier interpolation.
maketform
Create structure for spatial transformations.
rotate_scale
Arbitrary rotation and scaling of a gray-scale image using fast bilinear interpolation.
tformfwd
Given to dimensionnal coordinates from one space, returns two dimensionnal coordinates in the other space, as defined in the transform structure T.
tforminv
Given to dimensionnal coordinates from one space, returns two dimensionnal coordinates in the other space, as defined in the transform structure T.

Types and Type conversions

grayslice
Creates an indexed image X from an intensitiy image I using multiple threshold levels.
graythresh
Compute global image threshold.
im2bw
Convert image to binary, black and white, by threshold.
im2double
Convert input image IM1 to double precision.
im2int16
Convert input image IM1 to int16 precision.
im2single
Convert input image IM1 to single precision.
im2uint8
Convert input image IM1 to uint16 precision.
im2uint16
Convert input image IM1 to uint16 precision.
imdither
Reduce the number a colors of rgb or indexed image.
isbw
Return true if IMG is a black and white image.
isgray
Return true if IMG is an indexed image.
isind
Return true if IMG is an indexed image.
isrgb
Return true if IMG is a RGB image.
label2rgb
Convert labeled image into RGB.
mat2gray
Convert a matrix to an intensity image.
rgb2gray
Convert RGB image or colormap to grayscale.

Utilities

checkerboard
Create checkerboard.
getrangefromclass
Return display range of image.
iptcheckconn
Check if argument is valid connectivity.
iptcheckmap
Check if argument is valid colormap.
iptchecknargin
Checks for correct number of arguments.
iptcheckstrs
Check if argument is a valid string.
iptnum2ordinal
Convert number to ordinal string.
padarray
Pad array or matrix.
phantom
Create computational phantom head.

Package: image