Routines (by topic) > Image Processing

# Image Processing Routines

## Contrast Enhancement and Filtering

ADAPT_HIST_EQUAL - Perform adaptive histogram equalization

BANDPASS_FILTER - Apply a bandpass filter to a one-channel image.

BANDREJECT_FILTER - Apply a band reject filter on a one-channel image.

BUTTERWORTH - Return the absolute value of the low-pass Butterworth kernel.

BYTSCL - Scale all values of an array into range of bytes.

CANNY - Perform the Canny edge-detection algorithm.

CONVOL - Convolve two vectors or arrays.

DIGITAL_FILTER - Calculate coefficients of a non-recursive, digital filter.

ESTIMATOR_FILTER - Apply an order statistic noise-reduction filter to an image.

FFT - Return the Fast Fourier Transform of an array.

HILBERT - Construct a Hilbert transform.

HIST_EQUAL - Histogram-equalize an image.

IR_FILTER - Perform the infinite or finite impulse response filter on data.

LEAST_SQUARES_FILTER - Reduces degradation and noise in an image.

LEEFILT - Perform the Lee filter algorithm on an image array.

MEAN_FILTER - Apply mean filter noise reduction on a one- or multi-channel image.

MEDIAN - Return the median value of Array or applies a median filter.

ROBERTS - Return an approximation of Roberts edge enhancement.

SMOOTH - Smooth with a boxcar average.

SOBEL - Return an approximation of Sobel edge enhancement.

UNSHARP_MASK - Perform an unsharp-mask sharpening filter.

WIENER_FILTER - Reduce degradation and noise in an image.

## Feature Extraction/Image Segmentation

DEFROI - Defines an irregular region of interest of an image. (Direct Graphics)

HISTOGRAM - Computes the density function of an array.

HOUGH - Return the Hough transform of an image.

IMAGE_STATISTICS - Compute sample statistics for a given array of values.

IMAGE_THRESHOLD - Generate a threshold value for an image.

ISOCONTOUR - Perform a contouring algorithm.

ISOSURFACE - Return topologically consistent triangles by using oriented tetrahedral decomposition.

LABEL_REGION - Label regions (blobs) of a bi-level image.

MEDIAN - Return the median value of Array or applies a median filter.

PROFILES Procedure - Interactively examines image profiles.

RADON - Return the Radon transform of an image.

REGION_GROW - Perform region growing.

SEARCH2D - Finds objects or regions of similar data within a 2D array.

THIN - Return the skeleton of a bi-level image.

UNIQ - Return subscripts of the unique elements in an array.

WATERSHED - Apply the morphological watershed operator to a grayscale image.

WHERE - Return subscripts of nonzero array elements.

## Image Display

DISSOLVE - Provides a digital “dissolve” effect for images.

IDLgrImage - Create an image object.

IDLgrPalette - An object that contains a red-green-blue color lookup table.

SMOOTH - Creates a scrolling graphics window for examining large images.

TV - Displays an image. To scale and display the image, use TVSCL. (Direct Graphics)

TVCRS - Manipulates the image display cursor. (Direct Graphics)

TVLCT - Loads display color tables. (Direct Graphics)

TVSCL - Scales and displays an image. (Direct Graphics)

ZOOM - Zooms portions of the display. (Direct Graphics)

ZOOM_24 - Zooms portions of true-color (24-bit) display. (Direct Graphics)

## Image Geometry Transformations

CONGRID - Resamples an image to any dimensions.

EXPAND - Shrinks/expands image using bilinear interpolation.

EXTRAC - Return sub-matrix of input array. Array operators (e.g., * and :) should usually be used instead.

INTERPOLATE - Return an array of interpolates.

INVERT - Computes the inverse of a square array.

POLY_2D - Perform polynomial warping of images.

POLYWARP - Perform polynomial spatial warping.

REBIN - Resizes a vector or array by integer multiples.

REFORM - Changes array dimensions without changing the total number of elements.

REVERSE - Reverses the order of one dimension of an array.

ROT - Rotates an image by any amount.

ROTATE - Rotates/transposes an array in multiples of 90 degrees.

SHIFT - Shifts elements of vectors or arrays by a specified number of elements.

TRANSPOSE - Transposes an array.

WARP_TRI - Warps an image using control points.

## Morphological Image Operators

DILATE - Implements morphologic dilation operator on binary and grayscale images.

ERODE - Implements the erosion operator on binary and grayscale images and vectors.

LABEL_REGION - Labels regions (blobs) of a bi-level image.

MORPH_CLOSE - Apply closing operator to binary or grayscale image.

MORPH_DISTANCE - Estimates N-dimensional distance maps, which contain for each foreground pixel the distance to the nearest background pixel, using a given norm.

MORPH_GRADIENT - Apply the morphological gradient operator to a grayscale image.

MORPH_HITORMISS - Apply the hit-or-miss operator to a binary image.

MORPH_OPEN - Apply the opening operator to a binary or grayscale image.

MORPH_THIN - Perform a thinning operation on binary images.

MORPH_TOPHAT - Apply top-hat operator to a grayscale image.

WATERSHED - Apply the morphological watershed operator to a grayscale image.

## Regions of Interest

CW_DEFROI - Creates compound widget used to define region of interest. (Direct Graphics)

DEFROI - Defines an irregular region of interest of an image. (Direct Graphics)

DRAW_ROI - Draws region or group of regions to current Direct Graphics device. (Direct Graphics)

IDLanROI - Represents a region of interest used for analysis.

IDLanROIGroup - Analytical representation of a group of regions of interest.

IDLgrROI - Object graphics representation of a region of interest.

IDLgrROIGroup - Object Graphics representation of a group of regions of interest.

LABEL_REGION - Labels regions (blobs) of a bi-level image.

REGION_GROW - Grows an initial region to include all areas that match specified constraints.

XROI - Utility for defining regions of interest, and obtaining geometry and statistical data about these ROIs.